DOE-HDBK-1028-2009, Human Performance Improvement Handbook, Volume 1 (Part 1 of 2, links to all Volumes)
This Human Performance Improvement Handbook is a reference for anyone working in the Department of Energy (DOE) community who wants to learn more about human performance and how it can be improved.The handbook addresses the roles of individuals, leaders, and the organization in improving performance. [Multi-part Document]
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Section 1
NOT MEASUREMENT
SENSITIVE
DOE-HDBK-1028-2009
June 2009
DOE STANDARD
HUMAN PERFORMANCE
IMPROVEMENT HANDBOOK
VOLUME 1: CONCEPTS AND
PRINCIPLES
U.S. Department of Energy AREA HFAC
Washington, D.C. 20585
DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
Available on the Department of Energy
Technical Standards Program
Web site at
http://www.hss.energy.gov/nuclearsafety/ns/techstds/
DOE-HDBK-1028-2009
VOLUME 1: CONCEPTS AND PRINCIPLES
PREFACE ....................................................................................................................... v
Reading The Handbook ............................................................................................... vi
CHAPTER 1 - INTRODUCTION TO HUMAN PERFORMANCE..............1-1
OVERVIEW..................................................................................................................1-1
Perspective on Human Performance and Events................................................1-10
Human Performance for Engineers and Knowledge Workers .............................1-11
The Work Place...................................................................................................1-11
Individuals, Leaders, and Organizations .............................................................1-12
HUMAN PERFORMANCE.........................................................................................1-12
Behavior ..............................................................................................................1-13
ANATOMY OF AN EVENT
STRATEGIC APPROACH FOR HUMAN PERFORMANCE
........................................................................................1-14
Event
Initiating Action
Flawed Controls
Error Precursors
Latent Organizational Weaknesses
Reducing Error
Managing Controls
...................................................................................................................1-14
....................................................................................................1-14
..................................................................................................1-15
..................................................................................................1-15
.....................................................................1-15
.....................................1-16
....................................................................................................1-16
..............................................................................................1-17
PRINCIPLES OF HUMAN PERFORMANCE
REFERENCES
............................................................1-19
...........................................................................................................1-21
CHAPTER 2 - REDUCING ERROR .........................................................2-1
HUMAN FALLIBILITY (Essential Reading) ...............................................................2-1
Common Traps of Human Nature
Unsafe Attitudes and At-Risk Behaviors
Slips, Lapses, Mistakes, Errors and Violations
Active Errors
Latent Errors
Violations
Dependency and Team Errors
Equipment Dependencies
.........................................................................2-1
...............................................................2-4
......................................................2-8
..........................................................................................................2-8
Section 2
.........................................................................................................2-9
.............................................................................................................2-10
............................................................................2-11
...................................................................................2-11
i
DOE-HDBK-1028-2009
Team Errors
Personal Dependencies
........................................................................................................2-12
......................................................................................2-15
PERFORMANCE MODES (Essential Reading)
ERROR-LIKELY SITUATIONS (Essential Reading)
.......................................................2-16
Information Processing, Memory, and Attention
Generic Error Model System (GEMS)
Skill-Based Performance
Examples of Skill-Based Activities
Skill-Based Error Mode – Inattention
Rule-Based Performance
Examples of Rule-Based Activities
Rule-Based Error Mode
Knowledge-Based Performance
Examples of Knowledge-Based Activities
Knowledge-Based Error Mode
How Performance Modes Can be Used
Mental Models
Assumptions
Mental Biases – Shortcuts
Conservative Decisions
Error Precursors
Common Error Precursors
ERROR-PREVENTION TOOLS
..................................................2-16
.................................................................2-20
.....................................................................................2-21
......................................................................2-22
...................................................................2-22
....................................................................................2-23
......................................................................2-23
......................................................................................2-24
..........................................................................2-25
...........................................................2-26
............................................................................2-26
..............................................................2-27
.....................................................................................................2-28
........................................................................................................2-29
...................................................................................2-29
.......................................................................................2-30
................................................2-30
..................................................................................................2-31
..................................................................................2-32
..........................................................................2-33
ATTACHMENT A – ERROR PRECURSORS
ATTACHMENT B – COMMON ERROR-PRECURSOR DESCRIPTIONS
REFERENCES
CHAPTER 3 - MANAGING CONTROLS
............................................................2-35
................2-39
...........................................................................................................2-45
.................................................3-1
Controls
Severity of Events
The Organization’s Role in Controls
Defense Functions
Reliability of Controls
Section 3
.................................................................................................................3-1
.................................................................................................3-3
......................................................................3-3
................................................................................................3-4
............................................................................................3-4
DEFENSE-IN-DEPTH ..................................................................................................3-5
Engineered Controls
Administrative Controls
Cultural Controls – Values, Beliefs, Attitudes
.............................................................................................3-5
.........................................................................................3-6
........................................................3-8
ii
DOE-HDBK-1028-2009
Work Group Norms
Leadership Practices
Common Flaws with Cultural Controls
Oversight Controls
Senior Management Team Focus on Human Performance
Performance Improvement Processes
Human Performance Improvement Plans
...............................................................................................3-9
...........................................................................................3-10
................................................................3-10
..............................................................................................3-10
................................3-11
................................................................3-11
...........................................................3-12
PERFORMANCE MODEL
MANAGING CONTROLS – PERFORMANCE IMPROVEMENT MODEL
METHODS (Tools) FOR FINDING LATENT ORGANIZATIONAL CONDITIONS
.........................................................................................3-12
Organizational Effectiveness
Organizational Factors
Job-Site Conditions
Worker Behaviors
Plant Results
Self-Assessments
Behavior Observations
Problem Reporting
Benchmarking
Performance Indicators and Trending
Operating Experience
Independent Oversight
Problem Analysis
Management Oversight
Surveys and Questionnaires
Corrective Action Program
Change Management
...............................................................................3-13
........................................................................................3-14
.............................................................................................3-14
................................................................................................3-15
.......................................................................................................3-15
.................3-15
....3-17
...............................................................................................3-18
........................................................................................3-18
..............................................................................................3-19
.....................................................................................................3-19
.................................................................3-20
.........................................................................................3-20
........................................................................................3-21
Section 4
................................................................................................3-22
.......................................................................................3-23
...............................................................................3-23
..................................................................................3-23
..........................................................................................3-24
APPENDIX A: WARNING FLAGS—FACTORS THAT DEFEAT CONTROLS.........3-25
REFERENCES...........................................................................................................3-27
CHAPTER 4 - CULTURE AND LEADERSHIP ........................................4-1
ORGANIZATIONAL CULTURE...................................................................................4-1
SAFETY CULTURE.....................................................................................................4-2
How Organizations Process Information ...............................................................4-5
LEADERSHIP ............................................................................................................4-11
Leader’s Role ......................................................................................................4-11
Production and Prevention: Competing Purposes...............................................4-12
iii
DOE-HDBK-1028-2009
KEY LEADERSHIP PRACTICES ..............................................................................4-13
Facilitate Open Communication
Promote Teamwork
Reinforce Expectations
Eliminate Latent Organizational Weaknesses
Value the Prevention of Error
..........................................................................4-13
.............................................................................................4-13
.......................................................................................4-14
.....................................................4-16
..............................................................................4-17
BEHAVIOR ENGINEERING MODEL (BEM) .............................................................4-17
CREATE A JUST CULTURE.....................................................................................4-23
The Blame Cycle
Categories of Violations
The Foresight Test
The Substitution Test
The Culpability Decision Tree
.................................................................................................4-23
......................................................................................4-23
..............................................................................................4-24
..........................................................................................4-25
.............................................................................4-25
ATTACHMENT A – PERFORMANCE GAP ANALYSIS
ATTACHMENT B – CULPABILITY DECISION TREE
ATTACHMENT C – ESTABLISHING A REPORTING CULTURE
REFERENCES
CHAPTER 5 - HUMAN PERFORMANCE EVOLUTION
...........................................4-27
..............................................4-29
............................4-31
...........................................................................................................4-33
..........................5-1
INTRODUCTION
FACTORS THAT IMPACT ORGANIZATIONS
..........................................................................................................5-1
Section 5
A
Production
Quality Management
Human Factors and Ergonomics
Organizational Development
Learning Organizations
Human Performance Technology
Error Management
Mindfulness and Performance
High Reliability Organizations
Resilience Engineering
Organizational Resilience
Performance Improvement In the Work Place
Perspective on Organizations ............................................................................5-1
............................................................5-2
.............................................................................................................5-2
.............................................................................................5-3
...........................................................................5-4
.................................................................................5-6
.........................................................................................5-8
........................................................................5-10
..............................................................................................5-11
.............................................................................5-12
.............................................................................5-12
.......................................................................................5-16
....................................................................................5-17
.....................................................5-18
REFERENCES
GLOSSARY
CONCLUDING MATERIAL
...........................................................................................................5-21
..................................................................................................................... i
........................................................................................... xi
iv
DOE-HDBK-1028-2009
PREFACE
This Human Performance Improvement Handbook is a reference for anyone working in the
Department of Energy (DOE) community who wants to learn more about human performance
and how it can be improved. The handbook consists of five chapters entitled: “An Introduction
to Human Performance,” “Reducing Error,” “Managing Controls,” “Culture and Leadership”,
and “Organizations at Work.” The handbook addresses the roles of individuals, leaders, and the
organization in improving performance. Principles of human performance, outlined in Chapter
1, are the foundation blocks for the behaviors described and promoted in the handbook. The
strategic approach for improving performance is to reduce human error and manage controls so
as to reduce unwanted events and/or mitigate their impact should they occur. For the purposes of
this handbook, an event is an undesirable change in the state of structures, systems, or
components or human/organizational conditions (health, behavior, controls) that exceeds
established significance criteria.
Section 6
Human performance improvement (HPI) as addressed in this handbook is not a program per se,
such as Six Sigma, Total Quality Management, and the like. Rather, it is a set of concepts and
principles associated with a performance model that illustrates the organizational context of
human performance. The model contends that human performance is a system that comprises a
network of elements that work together to produce repeatable outcomes. The system
encompasses organizational factors, job-site conditions, individual behavior, and results. The
system approach puts new perspective on human error: it is not a cause of failure, alone, but
rather the effect or symptom of deeper trouble in the system. Human error is not random; it is
systematically connected to features of people’s tools, the tasks they perform, and the operating
environment in which they work. A separate volume, Human Performance Improvement
Handbook Volume II: Human Performance Tools for Individuals, Work Teams, and
Management, is a companion document to this handbook. That volume describes methods and
techniques for catching and reducing errors and locating and eliminating latent organizational
weaknesses
This volume is an introductory summary document that addresses a human performance
improvement approach as was initially introduced within DOE in recent years. The content and
the approach to the topic are based on concepts and practices found useful in the commercial
nuclear power industry and similarly adopted by other industries. The Institute of Nuclear Power
Operations (INPO) generously provided assistance in helping the Department roll out its human
performance courses, which were patterned on the INPO model. This handbook reflects heavily
on the human performance research and practical applications so expertly chronicled in INPO’s
Human Performance Fundamentals Course Reference (2002) and its later revision of the
material in Human Performance Reference Manual, INPO 06-003 (2006). The Department is
greatly appreciative of this outstanding assistance and support. It is just one more recent
example of a long-standing collaborative relationship between these two organizations that spans
more than two decades.
The concept of high reliability organizations (HRO) has captured the interest of many
organizational leaders in recent years. HROs provide real examples of organizations that operate
successfully while almost never experiencing an unwanted event. HROs by definition operate
under very trying conditions all the time and yet manage to have very few accidents. (An
accident is an unfortunate mishap, especially one causing damage or injury.) Examples of HROs
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DOE-HDBK-1028-2009
include aircraft carriers, air traffic controllers, power grid dispatch centers, nuclear submarines,
airline cockpit crews, nuclear power plants, and offshore platforms, among others. HPI is one
approach toward achieving the attributes evident in HROs. (see Chapter 5)
This handbook is not a human factors manual. HPI is not a substitute for, nor is it intended to
impinge upon in any way on, the workings of human factors professionals to improve
organizational and individual effectiveness. Neither is it the intent of this handbook to modify
any requirements of other health, safety, and security regulations and obligations. The principles
of HPI can be used to enhance the value of these programs.
Reading The Handbook
Section 7
Individuals will approach the reading of this handbook either from a personal interest in the
subject matter or from a practical need to know the information contained in it. HPI trainers and
practitioners are likely to read it cover to cover, highlight sections, dog-ear certain pages and
make it one of their valued references. Managers, supervisors, and performance improvement
leaders wanting to learn about HPI with the goal of implementing it in their workplace will
approach reading in a somewhat different vein than persons who read it for their personal use.
The following guidance is intended to help users focus their reading.
Recommended Reading by User
Groups = X
Individual
Contributors
Managers
Supervisors
HPI Leaders
HPI Trainers
HPI Practioners
Chapter 1: Introduction to HPI X X X
Chapter 2: Reducing Error *X X X
Chapter 3: Managing Controls pp.1-17 X X
Chapter 4: Culture and Leadership X X
Chapter 5: HPI Evolution X
* Selected sections in Chapter 2 only are designated as “essential reading.”
Readers may come across unfamiliar terms while reading this handbook. If the term is not
defined in the text the first time it is used, refer to the glossary at the end of handbook for the
definition.
Both footnotes and endnotes are used in this document. The convention for footnotes is an
asterisk (*) followed by a number. Footnotes appear at the bottom of the page. Endnotes are
intended to reference source material. The convention for endnotes is a superscript number.
Endnotes are listed at the end of each chapter.
vi
Department of Energy Human Performance Handbook Chapter 1 Introduction
CHAPTER 1 - INTRODUCTION TO HUMAN PERFORMANCE
OVERVIEW
In its simplest form, human performance is a series of behaviors carried out to accomplish
specific task objectives (results). Behavior is what people do and say—it is a means to an end.
Behaviors are observable acts that can be seen and heard. In the Department of Energy (DOE)
the behaviors of operators, technicians, maintenance crafts, scientists and engineers, waste
handlers, and a myriad of other professionals are aggregated into cumulative acts designed to
achieve mission objectives. The primary objective of the operating facilities is the continuous
safe, reliable, and efficient production of mission-specific products. At the national laboratories,
the primary objectives are the ongoing discovery and testing of new materials, the invention of
new products, and technological advancement. The storage, handling, reconfiguration, and final
repository of the legacy nuclear waste materials, as well as decontamination, decommissioning,
and dismantling of old facilities and support operations used to produce America’s nuclear
defense capabilities during the Cold War are other significant mission objectives. Improving
human performance is a key in improving the performance of production facilities, performance
of the national laboratories, and performance of cleanup and restoration.
It is not easy to anticipate exactly how trivial conditions can influence individual performance.
Error-provoking aspects of facility*1 design, procedures, processes, and human nature exist
everywhere. No matter how efficiently equipment functions; how good the training, supervision,
and procedures; and how well the best worker, engineer, or manager performs his or her duties,
people cannot perform better than the organization supporting them.1 Human error is caused not
only by normal human fallibility, but also by incompatible management and leadership practices
and organizational weaknesses in work processes and values. Therefore, defense-in-depth with
respect to the human element is needed to improve the resilience of programmatic systems and to
drive down human error and events.
Section 8
The aviation industry, medical industry, commercial nuclear power industry, U.S. Navy, DOE
and its contractors, and other high-risk, technologically complex organizations have adopted
human performance principles, concepts, and practices to consciously reduce human error and
bolster controls in order to reduce accidents and events. However, performance improvement is
not limited to safety. Organizations that have adopted human performance improvement (HPI)
methods and practices also report improved product quality, efficiency, and productivity.2 HPI,
as described in this handbook and practiced in the field, is not so much a program as it is a
distinct way of thinking. This handbook seeks to improve understanding about human
performance and to set forth recommendations on how to manage it and improve it to prevent
events triggered by human error.
This handbook promotes a practical way of thinking about hazards and risks to human
performance. It explores both the individual and leader behaviors needed to reduce error, as well
*1 The word “facility” used in this handbook is a generic term. It is recognized that D&D work is accomplished by
projects and that laboratory work is accomplished through experiments, etc. The reader should apply the term
“facility” to their recognized unit of work
1-1
Department of Energy Human Performance Handbook Chapter 1 Introduction
as improvements needed in organizational processes and values and job-site conditions to better
support worker performance. Fundamental knowledge of human and organizational behavior is
emphasized so that managers, supervisors, and workers alike can better identify and eliminate
error-provoking conditions that can trigger human errors leading to events in processing
facilities, laboratories, D & D structures, or anywhere else on DOE property. Ultimately, the
attitudes and practices needed to control these situations include:
• the will to communicate problems and opportunities to improve;
• an uneasiness toward the ability to err;
• an intolerance for error traps that place people and the facility at risk;
• vigilant situational awareness;
• rigorous use of error-prevention techniques; and
• understanding the value of relationships.
INTEGRATED SAFETY MANAGEMENT AND HPI
DOE developed and began implementation of Integrated Safety Management (ISM) in 1996.
Since that time, the Department has gained significant experience with its implementation. This
experience has shown that the basic framework and substance of the Department’s ISM program
remains valid. The experience also shows that substantial variances exist across the complex
regarding familiarity with ISM, commitment to implementation, and implementation
effectiveness. The experience further shows that more clarity of DOE’s role in effective ISM
implementation is needed. Contractors and DOE alike have reported that clearer expectations
and additional guidance on annual ISM maintenance and continuous improvement processes are
needed.
Section 9
Since 1996, external organizations that are also performing high-hazard work, such as
commercial nuclear organizations, Navy nuclear organizations, National Aeronautics and Space
Administration, and others, have also gained significant experience and insight relevant to safety
management. The ISM core function of “feedback and improvement” calls for DOE to learn
from available feedback and make changes to improve. This concept applies to the ISM program
itself. Lessons learned from both internal and external operating experience are reflected in the
ISM Manual to update the ISM program. The ISM Manual should be viewed as a natural
evolution of the ISM program, using feedback for improvement of the ISM program itself. Two
significant sources of external lessons learned have contributed to that Manual: (1) the research
and conclusions related to high-reliability organizations (HRO) and (2) the research and
conclusions related to the human performance improvement (HPI) initiatives in the commercial
nuclear industry, the U.S. Navy, and other organizations. HRO and HPI tenets are very
complementary with ISM and serve to extend and clarify the program’s principles and methods.3
As part of the ISM revitalization effort, the Department wants to address known opportunities for
improvement based on DOE experience and integrate the lessons learned from HRO
organizations and HPI implementation into the Department’s existing ISM infrastructure. The
1-2
Department of Energy Human Performance Handbook Chapter 1 Introduction
Department wants to integrate the ISM core functions, ISM principles, HRO principles, HPI
principles and methods, lessons learned, and internal and external best safety practices into a
proactive safety culture where:
� facility operations are recognized for their excellence and high-reliability;
� everyone accepts responsibility for their own safety and the safety of others;
� organization systems and processes provide mechanisms to identify systematic weaknesses
and assure adequate controls; and
� continuous learning and improvement are expected and consistently achieved.
The revitalized ISM system is expected to define and drive desired safety behaviors in order to
help DOE and its contractors create world-class safety performance.
In using the tools, processes, and approaches described in this HPI handbook, it is important to
implement them within an ISM framework, not as stand-alone programs outside of the ISM
framework. These tools cannot compete with ISM, but must support ISM. To the extent that
these tools help to clarify and improve implementation of the ISM system, the use of these tools
is strongly encouraged. The relationship between these tools and the ISM principles and
functions needs to be clearly understood and articulated in ISM system descriptions if these tools
impact on ISM implementation. It is also critical that the vocabulary and terminology used to
apply these tools be aligned with that of ISM. Learning organizations borrow best practices
whenever possible, but they must be translated into terms that are consistent and in alignment
with existing frameworks.
ISM Guiding Principles
The objective of ISM is to systematically integrate safety into management and work practices at
all levels so that work is accomplished while protecting the public, the workers, and the
environment. This objective is achieved through effective integration of safety management into
all facets of work planning and execution. In other words, the overall management of safety
functions and activities becomes an integral part of mission accomplishment. 4
Section 10
The seven guiding principles of ISMS are intended to guide Department and contractor actions
from development of safety directives to the performance of work. As reflected in the ISM
Manual ( DOE M 450.4-1dated 11-16-06) these principles are:
� Line Management Responsibility For Safety. Line management is directly responsible for
the protection of the public, the workers, and the environment.
� Clear Roles and Responsibilities. Clear and unambiguous lines of authority and
responsibility for ensuring safety shall be established and maintained at all organizational
levels within the Department and its contractors.
� Competence Commensurate with Responsibilities. Personnel shall possess the experience,
knowledge, skills, and abilities that are necessary to discharge their responsibilities.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
� Balanced Priorities. Resources shall be effectively allocated to address safety, programmatic,
and operational considerations. Protecting the public, the workers, and the environment shall
be a priority whenever activities are planned and performed.
� Identification of Safety Standards and Requirements. Before work is performed, the
associated hazards shall be evaluated and an agreed-upon set of safety standards and
requirements shall be established which, if properly implemented, will provide adequate
assurance that the public, the workers, and the environment are protected from adverse
consequences.
� Hazard Controls Tailored to Work Being Performed. Administrative and engineering
controls to prevent and mitigate hazards shall be tailored to the work being performed and
associated hazards.
� Operations Authorization. The conditions and requirements to be satisfied for operations to
be initiated and conducted shall be clearly established and agreed upon.
ISM Core Functions
Five ISM core functions provide the necessary safety management structure to support any work
activity that could potentially affect the public, workers, and the environment. These functions
are applied as a continuous cycle with the degree of rigor appropriate to address the type of work
activity and the hazards involved.
• Define the Scope of Work. Missions are translated into work; expectations are set; tasks
are identified and prioritized; and resources are allocated.
• Analyze the Hazards. Hazards associated with the work are identified, analyzed, and
categorized.
• Develop and Implement Hazard Controls. Applicable standards and requirements are
identified and agreed-upon; controls to prevent or mitigate hazards are identified; the
safety envelope is established; and controls are implemented.
• Perform Work within Controls. Readiness to do the work is confirmed and work is
carried out safely.
• Provide Feedback and Continuous Improvement. Feedback information on the adequacy
of controls is gathered; opportunities for improving how work is defined and planned are
identified and implemented; line and independent oversight is conducted; and, if
necessary, regulatory enforcement actions occur.
Human error can have a negative affect at each stage of the ISM work cycle; for example:.
1. Define Work Scope: Errors in defining work can lead to mistakes in analyzing hazards.
2. Analyze Hazards: Without the correct hazards identified, errors will be made in
identifying adequate controls.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
Section 11
3. Develop Controls: Without an effective set of controls, minor work errors can lead to
significant events.
4. Perform Work: If the response to the event only focuses on the minor work error, the
other contributing errors will not be addressed.
Integration of ISM and HPI
Work planning and control processes derived from ISM*2 are key opportunities for enhancement
by application of HPI concepts and tools. In fact, an almost natural integration can occur when
the HPI objectives—reducing error and strengthening controls - are used as integral to
implementing the ISM core functions. Likewise the analytical work that goes into reducing
human error and strengthening controls supports the ISM core functions.
For purposes of this Handbook, a few examples of this integration are illustrated in the
following table. The ISM core functions are listed in the left column going down the table. The
HPI objectives appear as headers in the second and third column on the table.
*2 For a detailed discussion of work planning considerations, readers should refer to a document
published in January 2006 by the National Nuclear Security Administration (NNSA). That document is
entitled “Activity Level Work Planning and Control Processes : Attributes, Best Practices, and Guidance
for Effective Incorporation of Integrated Safety Management and Quality Assurance”.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
Integration of ISM and HPI
Integrated Safety Management Human Performance Improvement Strategic Approach
ISM Core Functions Reduce Human Error Manage Controls
Define the Scope of Work
The Task Preview HPI tool
supports this core function. It can
be used to help eliminate error
when reviewing the scope of
work. During the task preview
individuals who will perform the
work:
• Identify the critical steps (see
definition)
When management expectations
are set. the tasks are identified
and prioritized, and resources
are properly allocated (e.g.,
supervision, tools, equipment,
work control, engineering
support, training), human
performance can flourish. These
organizational factors create a
unique array of job-site
conditions – a good work
environment – that sets people
up for success. Human error
When work scope is defined and
all the preparation to complete the
task is at hand, the error
precursors – conditions that
provoke error – are reduced. This
includes things such as:
• Unexpected equipment
conditions
• Workarounds
• Departures from the routine
• Consider the possible errors
associated with each critical
step and the likely
increases when expectations are
not set, tasks are not clearly
identified, and resources are not
available to carry out the job.
• Unclear standards
• Need to interpret requirements
consequences.
• Ponder the "worst that could
happen."
• Consider the appropriate
human performance tool(s) to
use.
• Discuss other controls,
contingencies, and relevant
operating experience.
This approach is intended to
expand the work definition
considerations and thus preclude
omissions that could be
overlooked during analyzing the
hazards associated with the work
to be accomplished.
Properly managing controls is
dependent on the elimination of
error precursors that challenge the
integrity of controls and allow
human error to become
consequential.
1-6
Department of Energy Human Performance Handbook Chapter 1 Introduction
Integrated Safety Management Human Performance Improvement Strategic Approach
Section 12
ISM Core Functions Reduce Human Error Manage Controls
Analyze and Categorize the When hazards are properly Reducing latent weaknesses in the
Hazards*3 analyzed during the ISM cycle,
the results can be used to
procedures strengthens the
engineering and administrative
All types of hazards (e.g., nuclear, analyze the work procedure for controls that are an important
industrial, chemical) to workers, latent weaknesses and initiate cornerstone of the overall defense
the public, and the environment. procedure changes to eliminate system.
HPI tools that support this core
function including job-site review,
pre-job briefing, and questioning
attitude. These tools can be used
those weaknesses. Similarly,
robust hazards analysis should
consider error precursors in the
work place such as:
Strong administrative and cultural
controls can withstand human
error. Controls are weakened
when conditions are present that
to identify hazards and unsafe Adverse environmental provoke error.
conditions before starting a job. conditions
Unclear roles/responsibilities
Time pressures
High workload
Confusing displays or controls
Eliminating error precursors at the
job site (in the workplace) reduces
the incidences of active errors.
Develop and Implement Hazard The ISM core function, Hazard controls initiated in the ISM
Controls Implement Hazard Controls,
improves conditions at the job-
framework are supplemental
reinforcements to the engineered
HPI Principle 2, “Error-likely site. HPI describes the job site and administrative controls and
situations are predictable, as the location where behavior barriers discussed in association
manageable, and preventable,” occurs during task performance with the HPI performance model
complements this ISM core and is characterized by both (Chapter 3). Hazard controls not
function. Hazards are the environmental and individual only help ensure worker and
markings for error-likely situations factors. Environmental factors environmental safety, hazard
– a work situation in which there include conditions external to the controls also relieve workers from
is greater opportunity for error individual and often beyond his worry, stress, and anxiety when
when performing a specific action or her direct control, such as performing work in the face of
or task due to error traps. The procedure quality, component known hazards. Such conditions
recognition in HPI that error-likely labeling, human-machine provoke human error and
situations can be managed and interface, heat, and humidity. mistakes. When hazard controls
prevented supports the ISM core Individual factors include are in place, worker stress and
function that hazards are conditions that are a function of anxiety drops, human performance
identifiable and controllable. the person assigned the task,
such as knowledge, skills,
improves, and human error
decreases.
HPI tools that support this core experience, family problems,
function are self-checking, peer and color blindness.
check, procedure use and
adherence.
*3 Hazards analysis in DOE is an iterative and multi-disciplined process that begins with gross analysis in the
earlier stages of work planning and proceeds to ever more detail refinements that determine the controls to be used.
Because the qualifications of work planners varies across DOE, hazards analysis for many work activities requires
input of engineers, scientists, safety professional staff and work performers. This chart is merely illustrative of how
HPI concepts and tools can add new dimensions to the execution of the ISM functions. For more information on
Hazards Analysis, refer to 10CFR830 and DOE Order 414.1.
Section 13
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Department of Energy Human Performance Handbook Chapter 1 Introduction
Integrated Safety Management Human Performance Improvement Strategic Approach
ISM Core Functions Reduce Human Error Manage Controls
Perform Work This ISM core function supports
the third HPI Principle,
The core value expectation that
work can be performed safely is
The consistent and effective use
of HPI error-reduction tools when
performing work reduces the
probability that an active error
may cause an accident or serious
event. Error-reduction tools
include among others:
“Individual behavior is influenced
by organizational processes and
values.” When operations
authorization is performed
correctly, it can be used as an
independent verification of the
work planning and control
process for specific tasks.
balanced by the first principle of
HPI that states, “People are
fallible, and even the best people
make mistakes.” Because people
err and make mistakes, it is all the
more important that controls are
implemented and properly
maintained.
• Self-checking Management can use this
verification process to ensure
• Questioning attitude that the organizational
processes and values are in
• Stop when unsure place to adequately support
performance at the job-site (i.e.,
• Effective communication the task and the individuals are
properly aligned and supported
• Procedure use and adherence to successfully complete the
• Peer-checking
work).
• Second-person verifications
• Turnovers
Descriptions of these and other
HPI tools are in Volume 2.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
Integrated Safety Management Human Performance Improvement Strategic Approach
ISM Core Functions Reduce Human Error Manage Controls
Feedback and Improvement The fifth principle of HPI is that
Events can be avoided through
Line management and
independent oversight are
The post-job review supports this an understanding of the reasons important controls that support
ISM core function. This HPI tool mistakes occur and application “oversight control,” the fourth line
can help identify the adequacy of of the lessons learned from past of defense in the HPI defense
controls and point out events (or errors). hierarchy, as described in Chapter
opportunities for improving work
planning and execution. Topics
addressed during post-job
reviews includes among others:
• Surprises or unexpected
outcomes.
Even though errors during job
performance are inevitable, they
need not lead to events.
Seeking to understand the
reasons non-consequential
errors occur can help strengthen
3. Volume 2, section 3, of the HPI
manual describes several
management tools used to identify
and eliminate organizational
weaknesses that weaken controls.
• Usability and quality of work
documents
controls and make future
performance even better.
• Knowledge and skill
shortcomings
• Minor errors during the activity
• Unanticipated job-site
conditions
• Adequacy of tools and
resources
• Quality of work
planning/scheduling
• Adequacy of supervision
Investigating Events Triggered by
Human Error is an HPI tool used
to find system problems. When a
near miss or unwanted event
occurs, focusing attention on
problems beyond the individual –
deeper within the system (e.g.,
engineering flaws, manufacturing
flaws, weaknesses in work
processes, ineffective tools, poor
work conditions, training short-
falls) helps identify latent or
dormant organizational
conditions, which, if left
unresolved, can continue to
provoke mishaps and
occurrences.
Section 14
As illustrated in the table above, the integration of HPI methods and techniques to reduce error
and manage controls supports the ISMS core functions.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
The following leadership behaviors promoted in HPI (discussed in Chapter 4) support ISMS
Guiding Principle 1—line management responsibility for safety.
� Facilitate open communication.
� Promote teamwork.
� Reinforce desired behaviors.
� Eliminate latent organizational weaknesses.
� Value prevention of errors.
Perspective on Human Performance and Events
The graphic below illustrates what is known about the role of human performance in causing
events. About 80 percent of all events are attributed to human error. In some industries, this
number is closer to 90 percent. Roughly 20 percent of events involve equipment failures. When
the 80 percent human error is broken down further, it reveals that the majority of errors
associated with events stem from latent organizational weaknesses (perpetrated by humans in the
past that lie dormant in the system), whereas about 30 percent are caused by the individual
worker touching the equipment and systems in the facility.5 Clearly, focusing efforts on
reducing human error will reduce the likelihood of events.
Human Errors
80% Human Error 30%
Individual
Mistakes
20% Equipment
Events 70% due to
Organization
Weaknesses
Failures
An analysis of significant events in the commercial nuclear power industry between 1995 and
1999 indicated that three of every four events were attributed to human error, as reported by
INPO. Additionally, a Nuclear Regulatory Commission review of events in which fuel was
damaged while in the reactor showed that human error was a common factor in 21 of 26 (81
percent) events. The report disclosed that “the risk is in the people—the way they are trained,
their level of professionalism and performance, and the way they are managed.”6 Human error
leading to adverse consequences can be very costly: it jeopardizes an organization’s ability to
protect its workforce, its physical facility, the public, and the environment from calamity.
Human error also affects the economic bottom line. Very few organizations can sustain the costs
associated with a major accident (such as, product, material and facility damage, tool and
equipment damage, legal costs, emergency supplies, clearing the site, production delays,
overtime work, investigation time, supervisors’ time diverted, cost of panels of inquiry). It
should be noted that costs to operations are also incurred from errors by those performing
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Department of Energy Human Performance Handbook Chapter 1 Introduction
security, work control, cost and schedule, procurement, quality assurance, and other essential but
non-safety-related tasks. Human performance remains a significant factor for management
attention, not only from a safety perspective, but also from a financial one.7
A traditional belief is that human performance is a worker-focused phenomenon. This belief
promotes the notion that failures are introduced to the system only through the inherent
unreliability of people—Once we can rid ourselves of a few bad performers, everything will be
fine. There is nothing wrong with the system. However, experience indicates that weaknesses in
organizational processes and cultural values are involved in the majority of facility events.
Accidents result from a combination of factors, many of which are beyond the control of the
worker. Therefore, the organizational context of human performance is an important
consideration. Event-free performance requires an integrated view of human performance from
those who attempt to achieve it; that is, how well management, staff, supervision, and workers
function as a team and the degree of alignment of processes and values in achieving the facility’s
economic and safety missions.
Section 15
Human Performance for Engineers and Knowledge Workers
Engineers and other knowledge-based workers contribute differently than first-line workers to
facility events. A recent study completed for the Nuclear Regulatory Commission (NRC) by the
Idaho National Engineering and Environmental Laboratory (INEEL)8 indicates that human error
continues to be a causal factor in 79 percent of industry licensee events. Within those events,
there were four latent failures (undetected conditions that did not achieve the desired end(s) for
every active failure. More significantly, design and design change problems were a factor in 81
percent of the events involving human error. Recognizing that engineers and other knowledge-
based workers make different errors, INPO developed a set of tools specific to their needs.9
Many of these tools have been incorporated into DOE’s Human Performance Tools manual.
With engineers, specifically, the errors made can become significant if not caught early. As
noted in research conducted at one DOE site, because engineers as a group are highly educated,
narrowly focused, and have personalities that tend to be introverted and task-oriented, they tend
to be critical of others, but not self-critical.10 If they are not self-critical, their errors may go
undetected for long periods of time, sometimes years. This means that it is unlikely that the
engineer who made the mistake would ever know that one had been made, and the opportunity
for learning is diminished. Thus, human performance techniques aimed at this group of workers
need to be more focused on the errors they make while in the knowledge-based performance
mode as described in Chapter 2.
The Work Place
The work place or job site is any location where either the physical plant or the “paper” plant
(the aggregate of all the documentation that helps control the configuration of the physical plant)
can be changed. The systems, structures, and components used in the production processes make
up the physical plant. Error can come from either the industrial plant or the paper plant. All
human activity involves the risk of error. Flaws in the paper plant can lie dormant and can lead to
undesirable outcomes in the physical plant or even personal injury. Front-line workers “touch”
the physical plant as they perform their assigned tasks. Supervisors observe, direct, and coach
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Department of Energy Human Performance Handbook Chapter 1 Introduction
workers. Engineers and other technical staff perform activities that alter the paper plant or
modify processes and procedures that direct the activities of workers in the physical plant.
Managers influence worker and staff behavior by their oral or written directives and personal
example. The activities of all these individuals need to be controlled.
Individuals, Leaders, and Organizations
This handbook describes how individuals, leaders, and the organization as a whole
influence human performance. The role of the individual in human performance is
discussed in Chapter 2, “Reducing Error.” The role of the organization is discussed in
Chapter 3, “Managing Controls.” The role of the leader, as well as the leader’s
responsibilities for excellence in human performance, is discussed in Chapter 4,
“Culture and Leadership”. The following provides a general description of each of
theses entities:
� Individual — An employee in any position in the organization from yesterday’s new hire in
the storeroom to the senior vice president in the corner office.
Section 16
� Leader — Any individual who takes personal responsibility for his or her performance and
the facility's performance and attempts to positively influence the processes and values of the
organization. Managers and supervisors are in positions of responsibility and as such are
organizational leaders. Some individuals in these positions, however, may not exhibit
leadership behaviors that support this definition of a leader. Workers, although not in
managerial positions of responsibility, can be and are very influential leaders. The
designation as a leader is earned from subordinates, peers, and superiors.
� Organization — A group of people with a shared mission, resources, and plans to direct
people's behavior toward safe and reliable operation. Organizations direct people's behavior
in a predictable way, usually through processes and its value and belief systems. Workers,
supervisors, support staff, managers, and executives all make up the organization.
HUMAN PERFORMANCE
What is human performance? Because most people cannot effectively manage what they do not
understand, this question is a good place to start. Understanding the answer helps explain why
improvement efforts focus not only on results, but also on behavior. Good results can be
achieved with questionable behavior. In contrast, bad results can be produced despite compliant
behavior, as in the case of following procedures written incorrectly. Very simply, human
performance is behavior plus results (P = B + R). 11
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Department of Energy Human Performance Handbook Chapter 1 Introduction
Behavior
Behavior is what people do and say—a means to an end. Behavior is an observable act that can
be seen and heard, and it can be measured. Consistent behavior is necessary for consistent
results. For example, a youth baseball coach cannot just shout at a 10-year old pitcher from the
dugout to “throw strikes.” The child may not know how and will become frustrated. To be
effective, the coach must teach specific techniques—behaviors—that will help the child throw
strikes more consistently. This is followed up with effective coaching and positive
reinforcement. Sometimes people will make errors despite their best efforts. Therefore,
behavior and its causes are extremely valuable as the signal for improvement efforts to
anticipate, prevent, catch, or recover from errors. For long-term, sustained good results, a close
observation must be conducted of what influences behavior, what motivates it, what provokes it,
what shapes it, what inhibits it, and what directs it, especially when handling facility equipment.
Results
Performance infers measurable results. Results, good or bad, are the outcomes of behavior
encompassing the mental processes and physical efforts to perform a task.12 Within DOE, the
“end” is that set of outcomes manifested by people’s health and well-being; the environment; the
safe, reliable, and efficient production of defense products; the discovery of new scientific
knowledge; the invention and testing of new products; and the disposition of legacy wastes and
facilities. Events usually involve such things as challenges to reactor safety (where applicable),
industrial/radiological safety, environmental safety, quality, reliability, and productivity. Event-
free performance is the desired result, but is dependent on reducing error, both where people
touch the facility and where they touch the paper (procedures, instructions, drawings,
specifications, and the like). Event-free performance is also dependent on ensuring the integrity
of controls, controls, barriers, and safeguards against the residual errors that still occur.
Section 17
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Department of Energy Human Performance Handbook Chapter 1 Introduction
ANATOMY OF AN EVENT
Typically, events are triggered by human action. In most cases, the human action causing the
event was in error. However, the action could have been directed by a procedure; or it could
have resulted from a violation—a shortcut to get the job done. In any case, an act initiates the
undesired consequences. The graphic below provides an illustration of the elements that exist
before a typical event occurs. Breaking the linkages may prevent events.
Anatomy of an Event
Event
Vision,
Beliefs, &
Values
Latent
Organizational
Weaknesses
Mission
Goals
Policies
Processes
Programs
Flawed
Controls
Error
Precursors
Initiating
Action
Vision,
Beliefs, &
Values
Anatomy of an Event
Event
An event, as defined earlier, is an unwanted, undesirable change in the state of facility structures,
systems, or components or human/organizational conditions (health, behavior, administrative
controls, environment, etc.) that exceeds established significance criteria. Events involve serious
degradation or termination of the equipment’s ability to perform its required function. Other
definitions include: an outcome that must be undone; any facility condition that does not achieve
its goals; any undesirable consequence; and a difference between what is and what ought to be.
Initiating Action
The initiating action is an action by an individual, either correct, in error, or in violation, that
results in a facility event.13 An error is an action that unintentionally departs from an expected
behavior. A violation is a deliberate, intentional act to evade a known policy or procedure
requirement and that deviates from sanctioned organizational practices. Active errors are those
errors that have immediate, observable, undesirable outcomes and can be either acts of
commission or omission. The majority of initiating actions are active errors. Therefore, a
strategic approach to preventing events should include the anticipation and prevention of active
errors.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
Flawed Controls
Flawed controls are defects that, under the right circumstances, may inhibit the ability of
defensive measures to protect facility equipment or people against hazards or fail to prevent the
occurrence of active errors. Controls or barriers are methods that:
� protect against various hazards (such as radiation, chemical, heat);
� mitigate the consequences of the hazard (for example, reduced operating safety margin,
personal injury, equipment damage, environmental contamination, cost); and
� promote consistent behavior.
When an event occurs, there is either a flaw with existing controls or appropriate controls are not
in place.
Error Precursors
Error precursors are unfavorable prior conditions at the job site that increase the probability for
error during a specific action; that is, error-likely situations. An error-likely situation—an error
about to happen—typically exists when the demands of the task exceed the capabilities of the
individual or when work conditions aggravate the limitations of human nature.14 Error-likely
situations are also known as error traps.
Latent Organizational Weaknesses
Section 18
Latent organizational weaknesses are hidden deficiencies in management control processes (for
example, strategy, policies, work control, training, and resource allocation) or values (shared
beliefs, attitudes, norms, and assumptions) that create work place conditions that can provoke
errors (precursors) and degrade the integrity of controls (flawed controls).15 Latent
organizational weaknesses include system-level weaknesses that may exist in procedure
development and review, engineering design and approval, procurement and product receipt
inspection, training and qualification system(s), and so on. The decisions and activities of
managers and supervisors determine what is done, how well it is done, and when it is done,
either contributing to the health of the system(s) or further weakening its resistance to error and
events. System-level weaknesses are aggregately referred to as latent organizational weaknesses.
Consequently, managers and supervisors should perform their duties with the same uneasy
respect for error-prone work environments as workers. A second strategic thrust to preventing
events should be the identification and elimination of latent organizational weaknesses.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
STRATEGIC APPROACH FOR HUMAN PERFORMANCE
The strategic approach to improving human performance within the DOE community embraces
two primary challenges:
I. Anticipate, prevent, catch, and recover from active errors at the job site.
II. Identify and eliminate latent organizational weaknesses that provoke human error
and degrade controls against error and the consequences of error.
If opportunities to err are not methodically identified, preventable errors will not be eliminated.
Even if opportunities to err are systematically identified and prevented, people may still err in
unanticipated and creative ways. Consequently, additional means are necessary to protect
against errors that are not prevented or anticipated. Reducing the error rate minimizes the
frequency, but not the severity of events. Only controls can be effective at reducing the severity
of the outcome of error. Defense-in-depth—controls, or safeguards arranged in a layered
fashion—provides assurance such that if one fails, remaining controls will function as needed to
reduce the impact on the physical facility.
To improve human performance and facility performance, efforts should be made to (1) reduce
the occurrence of errors at all levels of the organization and (2) enhance the integrity of controls,
or safeguards discovered to be weak or missing. Reducing errors (Re) and managing controls
(Mc) will lead to zero significant events (ØE). The formula for achieving this goal is
Re + Mc → ØE. Eliminating significant facility events will result in performance improvement
within the organization.
Reducing Error
An effective error-reduction strategy focuses on work execution because these occasions present
workers with opportunities to harm key assets, reduce productivity, and adversely affect quality
through human error. Work execution involves workers having direct contact with the facility,
when they touch equipment and when knowledge workers touch the paper that influences the
facility (procedures, instructions, drawings, specifications, etc.). During work execution, the
human performance objective is to anticipate, prevent, or catch active errors, especially at critical
steps, where error-free performance is absolutely necessary. While various work planning
taxonomies may be used, opportunities for reducing error are particularly prevalent in what is
herein expressed as preparation, performing and feedback.*4
Section 19
• Preparation — planning – identifying the scope of work, associated hazards, and what is
to be avoided, including critical steps; job-site reviews and walkdowns – identifying
potential job-site challenges to error-free performance; task assignment – putting the right
*4 For a detailed discussion of work planning considerations, readers should refer to a document
published in January 2006 by the National Nuclear Security Administration (NNSA). That document is
entitled “Activity Level Work Planning and Control Processes : Attributes, Best Practices, and Guidance
for Effective Incorporation of Integrated Safety Management and Quality Assurance”.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
people on the job in light of the job’s task demands; and task previews and pre-job
briefings – identifying the scope of work including critical steps, associated hazards, and
what has to be avoided by anticipating possible active errors and their consequences.
• Performance — performing work with a sense of uneasiness; maintaining situational
awareness; rigorous use of human performance tools for important human actions,
avoiding unsafe or at-risk work practices; supported with quality supervision and
teamwork.
• Feedback — reporting – conveying information on the quality of work preparation,
related resources, and work place conditions to supervision and management; behavior
observations – workers receiving coaching and reinforcement on their performance in the
field through observations by managers and supervisors.
Chapter 2 focuses more on anticipating, preventing, and catching human error at the job-site.
Managing Controls
Events involve breaches in controls or safeguards. As mentioned earlier, errors still occur even
when opportunities to err are systematically identified and eliminated. It is essential therefore
that management take an aggressive approach to ensure controls function as intended. The top
priority to ensure safety from human error is to identify, assess, and eliminate hazards in the
workplace. These hazards are most often closely related to vulnerabilities with controls. They
have to be found and corrected. The most important aspect of this strategy is an assertive and
ongoing verification and validation of the health of controls. Ongoing self-assessments are
employed to scrutinize controls, and then the vulnerabilities are mended using the corrective
action program. A number of taxonomies of safety controls have been developed. For purposes
of this discussion of the HPI strategic approach, four general types of controls are reviewed in
brief.
• Control of Hazards by elimination or substitution – Organizations evaluate
operations, procedures and facilities to identify workplace hazards. Management
implements a hazard prevention and elimination process. When hazards are identified in
the workplace they are prioritized and actions are taken based on risks to the workers.
Management puts in place protective measures until such time as the hazard(s) can be
eliminated. An assessment of the hazard control(s) is carried out to verify that the actions
taken to eliminate the hazard are effective and enduring.*5
• Engineered features— These provide the facility with the physical ability to protect
from errors. To optimize this set of controls , equipment is reliable and is kept in a
configuration that is resistant to simple human error and allows systems and components
Section 20
*5 From the standpoint of worker safety, the following hierarchy of controls should govern: elimination or
substitution of the hazards when feasible; engineering controls; work practices and administrative controls; and
personnel protective equipment. Refer to 10 CFR Part 851 Federal Register, Worker Safety and Health Program;
June 28, 2006
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Department of Energy Human Performance Handbook Chapter 1 Introduction
to perform their intended functions when required. Facilities with high equipment
reliability, effective configuration control, and minimum human-machine vulnerabilities
tend to experience fewer and less severe facility events than those that struggle with these
issues. How carefully facility equipment is designed, operated, and maintained (using
human-centered approaches) affects the level of integrity of this line of protection.
• Administrative provisions— Policies, procedures, training, work practices processes,
administrative controls and expectations direct people’s activities so that they are
predictable and safe and limit their exposure to hazards, especially for work performed
in and on the facility. All together such controls help people anticipate and prepare for
problems. Written instructions specify what, when, where, and how work is to be done
and what personal protective equipment workers are to use. The rigor with which
people follow and perform work activities according to correctly written procedures,
expectations, and standards directly affects the integrity of this line of protection.
• Cultural norms — These are the assumptions, values, beliefs, and attitudes and the
related leadership practices that encourage either high standards of performance or
mediocrity, open or closed communication, or high or low standards of performance.
Personnel in highly reliable organizations practice error-prevention rigorously,
regardless of their perception of a task’s risk and simplicity, how routine it is, and how
competent the performer. The integrity of this line of defense depends on people’s
appreciation of the human’s role in safety, the respect they have for each other, and their
pride in the organization and the facility.
• Oversight — Accountability for personnel and facility safety, for security, and for ethical
behavior in all facets of facility operations, maintenance, and support activities is
achieved by a kind of “social contract” entered into willingly by workers and
management where a “just culture” prevails. In a just culture, people who make honest
errors and mistakes are not blamed while those who willfully violate standards and
expectations are censured. Workers willingly accept responsibility for the consequences
of their actions, including the rewards or sanctions (see “accountability” in the glossary).
They feel empowered to report errors and near misses. This accountability helps verify
margins, the integrity of controls and processes, as well as the quality of performance.
Performance improvement activities facilitate the accountability of line managers through
structured and ongoing assessments of human performance, trending, field observations,
and use of the corrective action program, among others. The integrity of this line of
defense depends on management’s commitment to high levels of human performance and
consistent follow-through to correct problems and vulnerabilities.
Chapter 3 focuses on controls and their management. Chapter 4 emphasizes the role managers
and informal leaders play in shaping safety culture.
Section 21
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Department of Energy Human Performance Handbook Chapter 1 Introduction
PRINCIPLES OF HUMAN PERFORMANCE
Five simple statements, listed below, are referred to as the principles or underlying truths of
human performance. Excellence in human performance can only be realized when individuals at
all levels of the organization accept these principles and embrace concepts and practices that
support them. These principles are the foundation blocks for the behaviors described and
promoted in this handbook. Integrating these principles into management and leadership
practices, worker practices, and the organization’s processes and values will be instrumental in
developing a working philosophy and implementing strategies for improving human
performance within your organization.
1. People are fallible, and even the best people make mistakes.
Error is universal. No one is immune regardless of age, experience, or educational level.
The saying, “to err is human,” is indeed a truism. It is human nature to be imprecise—to
err. Consequently, error will happen. No amount of counseling, training, or motivation can
alter a person's fallibility. Dr. James Reason, author of Human Error (1990) wrote: It is
crucial that personnel and particularly their managers become more aware of the human
potential for errors, the task, workplace, and organizational factors that shape their
likelihood and their consequences. Understanding how and why unsafe acts occur is the
essential first step in effective error management.
2. Error-likely situations are predictable, manageable, and preventable.
Despite the inevitability of human error in general, specific errors are preventable.16 Just as
we can predict that a person writing a personal check at the beginning of a new year stands
a good chance of writing the previous year on the check, a similar prediction can be made
within the context of work at the job site. Recognizing error traps and actively
communicating these hazards to others proactively manages situations and prevents the
occurrence of error. By changing the work situation to prevent, remove, or minimize the
presence of conditions that provoke error, task and individual factors at the job site can be
managed to prevent, or at least minimize, the chance for error.
3. Individual behavior is influenced by organizational processes and values.
Organizations are goal-directed and, as such, their processes and values are developed to
direct the behavior of the individuals in the organization. The organization mirrors the sum
of the ways work is divided into distinct jobs and then coordinated to conduct work and
generate deliverables safely and reliably. Management is in the business of directing
workers’ behaviors. Historically, management of human performance has focused on the
“individual error-prone or apathetic workers.”17 Work is achieved, however, within the
context of the organizational processes, culture, and management planning and control
systems. It is exactly these phenomena that contribute most of the causes of human
performance problems and resulting facility events.18
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Department of Energy Human Performance Handbook Chapter 1 Introduction
4. People achieve high levels of performance because of the encouragement and
reinforcement received from leaders, peers, and subordinates.
Section 22
The organization is perfectly tuned to get the performance it receives from the workforce.
All human behavior, good and bad, is reinforced, whether by immediate consequences or by
past experience. A behavior is reinforced by the consequences that an individual
experiences when the behavior occurs.19 The level of safety and reliability of a facility is
directly dependent on the behavior of people. Further, human performance is a function of
behavior. Because behavior is influenced by the consequences workers experience, what
happens to workers when they exhibit certain behaviors is an important factor in improving
human performance. Positive and immediate reinforcement for expected behaviors is ideal.
5. Events can be avoided through an understanding of the reasons mistakes occur and
application of the lessons learned from past events (or errors).
Traditionally, improvement in human performance has resulted from corrective actions
derived from an analysis of facility events and problem reports—a method that reacts to
what happened in the past. Learning from our mistakes and the mistakes of others is
reactive—after the fact—but important for continuous improvement. Human performance
improvement today requires a combination of both proactive and reactive approaches.
Anticipating how an event or error can be prevented is proactive and is a more cost-effective
means of preventing events and problems from developing.
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Department of Energy Human Performance Handbook Chapter 1 Introduction
REFERENCES
1 Maurino, Reason, Johnston, and Lee. Beyond Aviation Human Factors, 1995, p. xi.
2 Weick and Sutcliff. Managing the Unexpected: Assuring High Performance in an Age of Complexity, 2001,
Chapter 1; Longman, “The Best Care Anywhere. Washington Monthly. Jan, 2005; Department of Veterans
Affairs. Press Release, “VA Receives 2006 Innovations in Government Award” (July 10, 2006) Veterans
Administration shown to reduce costs and errors while increasing safety and efficiency. National Energy
Institute (NEI) www.nei.org/resources & statistics, reports the commercial nuclear power costs are down, while
proficiency is improving and significant events are decreasing.
3 Department of Energy 450.4-1, Integrated Safety Management Systems Manual, 2006, pp. 1-2
4 Department of Energy. Policy DOE P 450.4 Safety Management System Policy,1996. pp. 1-2
5 Perrow, Normal Accidents. Living with High-Risk Technologies, 1984, p. 183; Reason. Human Error. 1999,
p.187.
6 INPO 91-008. In-reactor Fuel Damaging Events.
7 Four out of five petrochemical organizations that suffer a major disaster without recovery procedures never reopen
for business. Reason. Managing the Risks of Organizational Accidents, 1998, p. 239.
8 NUREG/CR-6753. Review of Findings for Human Error Contribution to Risk in Operating Events, 2001, p. xi.
9 INPO 05-02 (Rev. 1). Human Performance Tools for Engineers and Knowledge Workers.
10 Van Der Molen, Schmidt, and Kruisman. Personality Characteristics of Engineers. Journal of Engineering
Education, October 2007, pp 495-50; William Rigot, WSRC. Engineering Mentoring Program at Savannah
River site highlighted a statistically significant correlation between personality profiles and Engineering Human
Performance. The DISC personality profile was administered to over 300 newly hired engineers and their
mentors over a 6-year period to help them understand their own personalities and how they related with others.
Approximately 70 percent of the sample population was in the ‘introverted/compliant/analytical’ quadrant.
These people tend to see things as more black and white, and have poor communication skills. While they view
the work of others very critically, they tend to be defensive of criticism of their own work.
Section 23
11 Gilbert. Human Competence, Engineering Worthy Performance, 1974, pp. 15-19.
12 Reber. Dictionary of Psychology, 1995, 2nd ed., pp. 86-87.
13 Senders and Moray. Human Error: Cause, Prediction, and Reduction, 1991, p. 20.
14 Reason. Managing the Risks of Organizational Accidents, 1998, p. 142.
15 Reason. Managing the Risks of Organizational Accidents, 1998, p. 10-18.
16 Center for Chemical Process Safety. Guidelines for Preventing Human Error in Process Safety, American
Institute of Chemical Engineers, 1994, pp.12-17, 103-107.
17 Reason. Managing the Risks of Organizational Accidents, 1998, p.127.
18 Demming. Out of the Crisis, 1986, p.315.
19 Daniels. Bringing Out the Best in People, 1994, pp.8-9.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
CHAPTER 2 - REDUCING ERROR
INTRODUCTION
As capable and ingenious as humans are, we do err and make mistakes. It is precisely this part
of human nature that we want to explore in the first part of this chapter. This inquiry includes
discussions of human characteristics, unsafe attitudes, and at-risk behaviors that make people
vulnerable to errors. A better understanding of what is behind the first principle of human
performance, “people are fallible, even the best make mistakes,” will help us better compensate
for human error through more rigorous use of error-reduction tools and by improving controls.
Certain sections of this chapter are considered essential reading and will be flagged as such at the
beginning of the section.
HUMAN FALLIBILITY (Essential Reading)
Human nature encompasses all the physical, biological, social, mental, and emotional
characteristics that define human tendencies, abilities, and limitations. One of the innate
characteristics of human nature is imprecision. Unlike a machine that is precise—each time,
every time—people are imprecise, especially in certain situations. For instance, humans tend to
perform poorly under high stress and time pressure. Because of “fallibility,” human beings are
vulnerable to external conditions that cause them to exceed the limitations of human nature.
Vulnerability to such conditions makes people susceptible to error. Susceptibility to error is
augmented when people work within complex systems (hardware or administrative) that have
concealed weaknesses—latent conditions that either provoke error or weaken controls against the
consequences of error.
Common Traps of Human Nature
People tend to overestimate their ability to maintain control when they are doing work.
Maintaining control means that everything happens that is supposed to happen during
performance of a task and nothing else. There are two reasons for this overestimation of ability.
First, consequential error is rare. Most of the time when errors occur, little or nothing happens.
So, people reason that errors will be caught or won’t be consequential. Second, there is a general
lack of appreciation of the limits of human capabilities. For instance, many people have learned
to function on insufficient rest or to work in the presence of enormous distractions or wretched
environmental conditions (extreme heat, cold, noise, vibration, and so on). These conditions
become normalized and accepted by the individual. But, when the limits of human capabilities
are exceeded (fatigue or loss of situational awareness, for example), the likelihood of error
increases. The common characteristics of human nature addressed below are especially
accentuated when work is performed in a complex work environment.
Section 24
Stress. Stress in itself is not a bad thing. Some stress is normal and healthy. Stress may result
in more focused attention, which in some situations could actually be beneficial to performance.
The problem with stress is that it can accumulate and overpower a person, thus becoming
detrimental to performance. Stress can be seen as the body’s mental and physical response to a
perceived threat(s) in the environment. The important word is perceived; the perception one has
about his or her ability to cope with the threat. Stress increases as familiarity with a situation
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decreases. It can result in panic, inhibiting the ability to effectively sense, perceive, recall, think,
or act. Anxiety and fear usually follow when an individual feels unable to respond successfully.
Along with anxiety and fear, memory lapses are among the first symptoms to appear. The
inability to think critically or to perform physical acts with accuracy soon follows.
Avoidance of Mental Strain. Humans are reluctant to engage in lengthy concentrated thinking,
as it requires high levels of attention for extended periods. Thinking is a slow, laborious process
that requires great effort.1 Consequently, people tend to look for familiar patterns and apply
well-tried solutions to a problem. There is the temptation to settle for satisfactory solutions
rather than continue seeking a better solution. The mental biases, or shortcuts, often used to
reduce mental effort and expedite decision-making include:
� Assumptions – A condition taken for granted or accepted as true without verification of the
facts.
� Habit – An unconscious pattern of behavior acquired through frequent repetition.
� Confirmation bias – The reluctance to abandon a current solution—to change one's mind—
in light of conflicting information due to the investment of time and effort in the current
solution. This bias orients the mind to “see” evidence that supports the original supposition
and to ignore or rationalize away conflicting data.2
� Similarity bias – The tendency to recall solutions from situations that appear similar to those
that have proved useful from past experience.
� Frequency bias – A gamble that a frequently used solution will work; giving greater weight
to information that occurs more frequently or is more recent.
� Availability bias – The tendency to settle on solutions or courses of action that readily come
to mind and appear satisfactory; more weight is placed on information that is available (even
though it could be wrong).3 4 This is related to a tendency to assign a cause-effect
relationship between two events because they occur almost at the same time.5
Limited Working Memory. The mind's short-term memory is the “workbench” for problem-
solving and decision-making. This temporary, attention-demanding storeroom is used to
remember new information and is actively involved during learning, storing, and recalling
information.6 Most people can reliably remember a limited number of items at a time often
expressed as 7+1 or -2. The limitations of short-term memory are at the root of forgetfulness;
forgetfulness leads to omissions when performing tasks. Applying place-keeping techniques
while using complex procedures compensates for this human limitation.
Section 25
Limited Attention Resources. The limited ability to concentrate on two or more activities
challenges the ability to process information needed to solve problems. Studies have shown that
the mind can concentrate on, at most, two or three things simultaneously.7 Attention is a limited
commodity—if it is strongly drawn to one particular thing it is necessarily withdrawn from other
competing concerns. Humans can only attend to a very small proportion of the available sensory
data. Also, preoccupation with some demanding sensory input or distraction by some current
thoughts or worries can capture attention. Attention focus (concentration) is hard to sustain for
extended periods of time. The ability to concentrate depends very much upon the intrinsic
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interest of the current object of attention.8 Self-checking (Stop, Think, Act, Review) is an
effective tool for helping individuals maintain attention.
Mind-Set. People tend to focus more on what they want to accomplish (a goal) and less on what
needs to be avoided because human beings are primarily goal-oriented by nature. As such,
people tend to “see” only what the mind expects, or wants, to see.9 The human mind seeks order,
and, once established, it ignores anything outside that mental model. Information that does not
fit a mind-set may not be noticed; hence people tend to miss conditions and circumstances which
are not expected. Likewise because they expect certain conditions and circumstances, they tend
to see things that are not really present.10 A focus on goal tends to conceal hazards, leading to
inaccurate perception of risks. Errors, hazards, and consequences usually result from either
incomplete information or assumptions. Pre-job briefings, if done mindfully, help people
recognize what needs to be avoided as well as what needs to be accomplished.
Difficulty Seeing One's Own Error. Individuals, especially when working alone, are
particularly susceptible to missing errors. People who are too close to a task, or are preoccupied
with other things, may fail to detect abnormalities. People are encouraged to “focus on the task
at hand.” However, this is a two-edged sword. Because of our tendency for mind-set and our
limited perspective, something may be missed. Peer-checking, as well as concurrent and
independent verification techniques, help detect errors that an individual can miss. Engineers
and some knowledge workers, by the nature of their focus on producing detailed information,
can be especially susceptible to not being appropriately self-critical.
Limited Perspective. Humans cannot see all there is to see. The inability of the human mind to
perceive all facts pertinent to a decision challenges problem-solving. This is similar to
attempting to see all the objects in a locked room through the door's keyhole. It is technically
known as “bounded rationality.”11 Only parts of a problem receive one's attention while other
parts remain hidden to the individual. This limitation causes an inaccurate mental picture, or
model, of a problem and leads to underestimating the risk.12 A well-practiced problem-solving
methodology is a key element to effective operating team performance during a facility
abnormality and also for the management team during meetings to address the problems of
operating and maintaining the facility.
Section 26
Susceptibility To Emotional/Social Factors. Anger and embarrassment adversely influence
team and individual performance. Problem-solving ability especially in a group may be
weakened by these and other emotional obstacles. Pride, embarrassment, and the group may
inhibit critical evaluation of proposed solutions, possibly resulting in team errors.
Fatigue. People get tired. In general, Americans are working longer hours now than a
generation ago and are sleeping less. Physical, emotional, and mental fatigue can lead to error
and poor judgment. Fatigue is affected by both on-the-job demands (production pressures,
environment, and reduced staffing) and off-duty life style (diet and sleep habits).13 Fatigue leads
to impaired reasoning and decision-making, impaired vigilance and attention, slowed mental
functioning and reaction time, loss of situational awareness, and adoption of shortcuts.
Acquiring adequate rest is an important factor in reducing individual error rate.
Presenteeism. Some employees will be present in the need to belong to the workplace despite a
diminished capacity to perform their jobs due to illness or injury. The tendency of people to
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continue working with minor health problems can be exacerbated by lack of sick leave, a
backlog of work, or poor access to medical care, and can lead to employees working with
significant impairments. Extreme cases can include individuals who fail to seek care for chronic
and disabling physical and mental health problems in order to keep working.
Unsafe Attitudes and At-Risk Behaviors
An attitude is a state of mind, or feeling, toward an object or subject. Attitudes are influenced by
many factors. They are formulated by one’s experiences, by examples and guidance from others,
through acquired beliefs and the like. Attitudes can develop as a result of educational
experiences, and, in such cases, it can be said that attitudes may be chosen.14 Attitudes can also
be acculturated—formulated by one’s experiences and influences from beliefs and behaviors
within one’s peer group. For example, the Mohawk Indians, often referred to as “skywalkers,”
are renowned for their extraordinary ability to walk high steel beams with balance and grace,
seemingly without any fear. It is commonly thought that this absence of fear of height was
inborn among the woodland Indians. It seems more likely that the trait was learned. 15
Anyone can possess an unsafe attitude. Unsafe attitudes are derived from beliefs and
assumptions about workplace hazards. Hazards are threats of harm. Harm includes physical
damage to equipment, personal injury, and even simple human error. Unsafe attitudes blind
people to the precursors to harm (exposure to danger). Notice that hazards are not confined to
the industrial facility; they exist in the office facility as well. The unsafe attitudes that are
described below are detrimental to excellent human performance and to the physical facility and
are usually driven by one’s perception of risk.
People in general are poor judges of risk and commonly underestimate it.
Examples of Risk Behaviors
Section 27
� Before the Park Service made it unlawful to feed the bears at Yellowstone National Park, in
the summer time a long line of automobiles would be stopped at the side the road where the
bears foraged for food in garbage cans. Tourists eagerly fed the animals through open
windows—a very risky business. Every day of the year in our larger cities, television news
cameras chronicle tragedies that have resulted from someone taking undue risks: trying to
beat the train at a railroad crossing; playing with a loaded firearm; swimming in dangerous
waters; binge drinking following the “big game”; and the like.
Each individual “decides” what to be afraid of and how afraid he or she should be. People often
think of risk in terms of probability, or likelihood, without adequately considering the possible
consequences or severity of the outcome. For instance, a mountain climber presumes he will not
slip or fall because most people don’t slip and fall when they climb. The climber gives little
thought to the consequences of a fall should one occur. (broken bones, immobility,
unconsciousness, no quick emergency response) People take the following factors into
consideration in varying degrees in assessing the risk of a situation.16 People are less afraid of
risks or situations:
• that they feel they have “control” over;
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• that provide some benefit(s) they want;
• the more they know about and ”live” with the hazard
• that they choose to take rather than those imposed on them;
• that are “routine” in contrast to those that are new or novel;
• that come from people, places, or organizations they trust;
• when they are unaware of the hazard(s);
• that are natural versus those that are man-made; and
• that affect others.
It has been said that risk perception tends to be guided more by our heart than our head. What
feels safe may, in fact, be dangerous. The following unsafe attitudes create danger in the work
place. Awareness of these unsafe, detrimental attitudes among the workforce is a first step
toward applying error-prevention methods.
• Pride. An excessively high opinion of one's ability; arrogance. Being self-focused, pride
tends to blind us to the value of what others can provide, hindering teamwork. People with
foolish pride think their competence is being called into question when they are corrected
about not adhering to expectations. The issue is human fallibility, not their competence.
This attitude is evident when someone responds, “Don't tell me what to do!” As commander
of the U.N. forces in Korea in 1950, General Douglas MacArthur (contrary to the President’s
strategy) sought to broaden the war against North Korea and China. President Truman and
the Joint Chiefs were fearful that MacArthur’s strategy, in opposition to the administration’s
“limited” war, could bring the Soviet Union into the war and lead to a possible third world
war. In April 1951, Truman fired MacArthur for insubordination. At the Senate Foreign
Relations and Armed Services committee hearing on MacArthur’s dismissal, the General
would admit to no mistakes, no errors of judgment, and belittled the danger of a larger
conflict.17
Section 28
• Heroic. An exaggerated sense of courage and boldness, like that of General George
Armstrong Custer. At Little Big Horn, he was so impetuous and eager for another victory
that he ignored advice from his scouts and fellow officers and failed to wait for
reinforcements that were forthcoming. He rode straight into battle against an overwhelming
force—the Sioux and Cheyenne braves—and to his death with over 200 of his men.18 Heroic
reactions are usually impulsive. The thinking is that something has to be done fast or all is
lost. This perspective is characterized by an extreme focus on the goal without consideration
of the hazards to avoid.
• Fatalistic. A defeatist belief that all events are predetermined and inevitable and that
nothing can be done to avert fate: “que será, será” (what will be will be) or “let the chips fall
as they may.” The long drawn-out trench warfare that held millions of men on the
battlefields of northern France in World War I caused excessive fatalistic responses among
the ranks of soldiers on both sides of the fighting. "Week after week, month after month,
year after year, the same failed offensive strategy prevailed. Attacking infantry forces
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always faced a protected enemy and devastating machine gun fire. Millions of men killed
and wounded, yet the Generals persisted. The cycle continued—over the top, early success,
then overwhelming losses and retreat."19
• Invulnerability. A sense of immunity to error, failure, or injury. Most people do not believe
they will err in the next few moments: “That can’t happen to me.” Error is always a surprise
when it happens. This is an outcome of the human limitation to accurately estimate risk.
The failure to secure enough lifeboats for all passengers and to train the seamen how to
launch them and load them ultimately resulted in the biggest maritime loss of civilian lives in
history on the Titanic. Invulnerability was so ingrained in the minds of the ship owners
about the ship being unsinkable that to supply the vessel with life boats for all passengers
was foolhardy and would somehow leave the impression that the ship could sink. Hence,
only half enough life boats were brought on board for the maiden voyage. When disaster
struck, seaman struggled to launch the available craft. In the panic and confusion, numerous
boats floated away from the mother ship only partially loaded.
• Pollyanna – All is well. People tend to presume that all is normal and perfect in their
immediate surroundings20 Humans seek order in their environment, not disorder. They tend
to fill in gaps in perception and to see wholes instead of portions.21 Consequently, people
unconsciously believe that everything will go as planned. This is particularly true when
people perform routine activities, unconsciously thinking nothing will go wrong. This belief
is characterized with quotes such as “What can go wrong?” or “It's routine.” This attitude
promotes an inaccurate perception of risk and can lead individuals to ignore unusual
situations or hazards, potentially causing them to react either too late or not at all.22
Section 29
• Bald Tire. A belief that past performance is justification for not changing (improving)
existing practices or conditions: “I've got 60,000 miles on this set of tires and haven't had a
flat yet.” A history of success can promote complacency and overconfidence. Evidence of
this attitude is characterized with quotes such as, “We haven't had any problems in the past,”
or “We've always done it this way.” Managers can be tempted to ignore recommendations
for improvement if results have been good. What happened with the Columbia space shuttle
is a good example. Over the course of 22 years, on every flight, some foam covering the
outer skin of the external fuel tank fell away during launch and struck the shuttle. Foam
strikes were normalized to the point where they were simply viewed as a “maintenance”
issue—a concern that did not threaten a mission’s success. In 2003, even after it became
clear from the launch videos that foam had struck the Orbiter in a manner never before seen,
Space Shuttle Program managers were not unduly alarmed. They could not imagine why
anyone would want a photo of something that could be fixed after landing. Learned attitudes
about foam strikes diminished management’s wariness of their danger.23
At-risk behaviors are actions that involve shortcuts, violations of error-prevention expectations,
or simple actions intended to improve efficient performance of a task, usually at some expense of
safety. At-risk practices involve a move from safety toward danger. These acts have a higher
probability, or potential, of a bad outcome. This does not mean such actions are “dangerous,” or
that they should not ever be performed. However, the worker and management should be aware
of at-risk practices that occur, under what circumstances, and on which systems. At-risk
behavior usually involves taking the path of least effort and is rarely penalized with an event, a
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personal injury, or even correction from peers or a supervisor. Instead it is consistently
reinforced with convenience, comfort, time savings, and, in rare cases, with fun.24
Examples of at-risk behaviors on the job
� hurrying through an activity;
� following procedures cookbook-style (blind or unthinking compliance);
� removing several danger tags quickly without annotating removal on the clearance sheet
when removed;
� reading an unrelated document while controlling an unstable system in manual;
� having one person perform actions at critical steps without peer checking or performing
concurrent verification;
� not following a procedure as required when a task is perceived to be “routine”;
� attempting to lift too much weight to reduce the number of trips;
� trying to listen to someone on the telephone and someone else standing nearby
(multitasking);
� signing off several steps of a procedure before performing the actions; or
� working in an adverse physical environment without adequate protection (such as working on
energized equipment near standing water—progress would be slowed to cleanup the water or
to get a rubber floor mat).
Risky behaviors at DOE worksites have contributed to events, some causing injury and death,
including:
� working on a hot electrical panel without wearing proper protective clothing;
� carrying heavy materials on an unstable surface while not using fall protection;
� failing to adhere to safety precautions when using a laser;
Section 30
� operating a forklift in a reckless manner;
� opening a hazardous materials storage tank without knowing the contents; and
� failing to follow procedures for safeguarding sensitive technical information.
Persistent use of at-risk behaviors builds overconfidence and trust in personal skills and ability.
This is a slippery slope, since people foolishly presume they will not err. Without correction, at-
risk behaviors can become automatic (skill-based), such as rolling through stop signs at
residential intersections. Over the long-term, people will begin to underestimate the risk of
hazards and the possibility of error and will consider danger (or error) as more remote.25 People
will become so used to the practice that, under the right circumstances, an event occurs.
Managers and supervisors must provide specific feedback when at-risk behavior is observed.
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Workers are more likely to avoid at-risk behavior if they know it is unacceptable. Without
correction, uneasiness toward equipment manipulations or intolerance of error traps will wane.
Slips, Lapses, Mistakes, Errors and Violations
Error. People do not err intentionally. Error is a human action that unintentionally departs from
an expected behavior.26 Error is behavior without malice or forethought; it is not a result.
Human error is provoked by a mismatch between human limitations and environmental
conditions at the job site, including inappropriate management and leadership practices and
organizational weaknesses that set up the conditions for performance.
Slips occur when the physical action fails to achieve the immediate objective. Lapses involve a
failure of one’s memory or recall. Slips and lapses can be classified by type of behavior when it
occurs with respect to physical manipulation of facility equipment.27 The following categories
describe how an incorrect or erroneous action can physically manifest itself or ways an action
can go wrong:
� timing – too early, too late, omission;
� duration – too long, too short;
� sequence – reversal, repetition, intrusion;
� object – wrong action on correct object, correct action on wrong object;
� force – too little or too much force;
� direction – incorrect direction;
� speed – too fast or too slow; and
� distance – too far, too short.
Mistakes, by contrast, occur when a person uses an inadequate plan to achieve the intended
outcome. Mistakes usually involve misinterpretations or lack of knowledge. 28
Active Errors
Active errors are observable, physical actions that change equipment, system, or facility state,
resulting in immediate undesired consequences.29 The key
characteristic that makes the error active is the immediate unfavorable
result to facility equipment and/or personnel. Front-line workers
commit most of the active errors because they touch equipment.
Most errors are trivial in nature, resulting in little or no consequence,
and may go unnoticed or are easily recovered from. However,
grievous errors may result in loss of life, major personal injury, or
severe consequences to the physical facility, such as equipment damage. Active errors spawn
immediate, unwanted consequences.
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Latent Errors
Section 31
Latent errors result in hidden organization-related weaknesses or
equipment flaws that lie dormant.30 Such errors go unnoticed at the
time they occur and have no immediate apparent outcome to the
facility or to personnel. Latent conditions include actions, directives,
and decisions that either create the preconditions for error or fail to
prevent, catch, or mitigate the effects of error on the physical facility.
Latent errors typically manifest themselves as degradations in
defense mechanisms, such as weaknesses in processes, inefficiencies,
and undesirable changes in values and practices. Latent conditions include design defects,
manufacturing defects, maintenance failures, clumsy automation, defective tools, training
shortcomings, and so on. Managers, supervisors, and technical staff, as well as front-line
workers, are capable of creating latent conditions. Inaccuracies become embedded in paper-
based directives, such as procedures, policies, drawings, and design bases documentation.
Workers unknowingly alter the integrity of physical facility equipment, such as the installation of
an incorrect gasket, mispositioning a valve, hanging a danger tag on the wrong component, or
attaching an incorrect label.
Usually, there is no immediate feedback that an error has been made. Engineers have performed
key calculations incorrectly that slipped past subsequent reviews, invalidating the design basis
for safety-related equipment. Craft personnel have undermined equipment performance by
installing a sealing mechanism incorrectly, which is not discovered until the equipment is called
upon to perform its function. The table below summarizes the general characteristics of each
kind of error.
Active Errors Latent Errors
Who? Workers Managers, engineers,
workers, corporate and
support staff
What? Equipment Paper, values, and beliefs
When? Immediately Later or delayed, dormant
Visible? Yes No
As one can see from the table, latent errors are more subtle and threatening than active errors,
making the facility more vulnerable to events triggered by occasional active errors. A study,
sponsored by the Nuclear Regulatory Commission (NRC), focused on the human contribution to
35 events that occurred over a 6-year period in the nuclear power industry.31 Of the 270 errors
identified in those events, 81 percent were latent, and 19 percent were active. The NRC study
determined that design and design change errors and maintenance errors were the most
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significant contributors to latent conditions. The latent conditions or errors contributed most
often to facility events and caused the greatest increases in risk.
Violations
Violations are characterized as the intentional (with forethought) circumvention of known rules
or policy. A violation involves the deliberate deviation or departure from an expected behavior,
policy, or procedure. Most violations are well intentioned, arising from a genuine desire to get a
job done according to management’s wishes. 32 Such actions may be either acts of omission (not
doing something that should be done) or commission (doing something wrong). Usually adverse
consequences are unintended—violations are rarely acts of sabotage. The deliberate decision to
violate a rule is a motivational or cultural issue. The willingness to violate known rules is
generally a function of the accepted practices and values of the immediate work group and its
leadership, the individual’s character, or both. In some cases, the individual achieved the desired
results wanted by the manager while knowingly violating expectations. Workers, supervisors,
managers, engineers, and even executives can be guilty of violations.
Section 32
Violations are usually adopted for convenience, expedience, or comfort. Events become more
likely when someone disregards a safety rule or expectation. A couple of strong situations that
tempt a person to do something other than what is expected involve conflicts between goals or
the outcome of a previous mistake. The individual typically underestimates the risk,
unconsciously assuming he or she will not err, especially in the next few moments. People are
generally overconfident about their ability to maintain control.
Examples: When People Commit Violations
Research has found that the following circumstances, in order of influence, prompt a person to
violate expectations.33
� low potential for detection
� absence of authority in the immediate vicinity
� peer pressure by team or work group
� emulation of role models (according to the individual concerned)
� individual’s perception that he or she possesses the authority to change the standard
� standard is unimportant to management
� unawareness of potential consequences; perceived low risk
� competition with other individuals or work groups
� interferences or obstacles to achieving the work goal
� conflicting demands or goals forcing the individual to make a choice
� precedent: “We've always done it this way” (tacitly acceptable to authority)
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The discussion on violations intends to help clarify the differences between the willful,
intentional decision to deviate associated with violations and the unintended deviation from
expected behavior associated with error. This handbook focuses on managing human error.
Dependency and Team Errors
For controls to be reliable, they must be independent; that is, the failure of one does not lead to
the failure of another. If the strength of one barrier can be unfavorably influenced by another
barrier or condition, they are said to be dependent. Dependency increases the likelihood of
human error due to the person’s interaction or relationship with other seemingly independent
defense mechanisms. For example, in the rail transportation industry, although a train engineer
monitors railway signals during transit, automatic warning signals are built into the
transportation system as a backup to the engineer. However, the engineer can become less
vigilant by relying on an automatic warning signal to alert him/her to danger on the track ahead.
What if the automatic signal fails as a result of improper maintenance intervals? Instead of one
barrier left (an alert engineer), no barriers are left to detect a dangerous situation. There are three
situations that can cause an unhealthy dependency, potentially defeating the integrity of
overlapping controls:34
� Equipment Dependencies – Lack of vigilance due to the assumption that
hardware controls or physical safety devices will always work.
� Team Errors – Lack of vigilance created by the social (interpersonal)
interaction between two or more people working together.
� Personal Dependencies – Unsafe attitudes and traps of human nature
leading to complacency and overconfidence.
Equipment Dependencies
Section 33
When individuals believe that equipment is reliable, they may reduce their level of vigilance or
even suspend monitoring of the equipment during operation. Automation, such as level and
pressure controls, has the potential to produce such a dependency. Boring tasks and highly
repetitive monitoring of equipment over long periods can degrade vigilance or even tempt a
person to violate inspection requirements, possibly leading to the falsification of logs or related
records. Monitoring tasks completed by a computer can also lead to complacency. In some
cases, the worker becomes a “common mode failure” for otherwise independent facility systems,
making the same error or assumption about all redundant trains of equipment or components.
Diminishing people’s dependencies on equipment can be addressed by:
� applying forcing functions and interlocks;
� eliminating repetitive monitoring of equipment through design modifications;
� alerting personnel to the failure of warning systems;
� staggering work activities on redundant equipment at different times or assigning different
persons to perform the same task;
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� diversifying types of equipment or components, thereby forcing the use of different practices;
for example, for turbine-driven and motor-driven pumps;
� training people on failure modes of automatic systems and how they are detected;
� informing people on equipment failure rates; and
� minimizing the complexity of procedures, tools, instrumentation, and controls.
Team Errors
Just because two or more people are performing a task does not ensure that it will be done
correctly. Shortcomings in performance can be triggered by the social interaction between group
members. In team situations, workers may not be fully attentive to the task or action because of
the influence of coworkers. This condition may increase the likelihood of error in some
situations. A team error is a breakdown of one or more members of a work group that allows
other individual members of the same group to err—due to either a mistaken perception of
another’s abilities or a lack of accountability within the individual’s group.
The logic diagram below illustrates the mathematical impact of such a dependency, using the
example of a supervisor (or peer) checking the performance of a maintenance technician.
Assuming complete independence between the technician and the supervisor, the overall
likelihood for error is one in a million; the overall task reliability is 99.9999 percent. However,
should the supervisor (or peer) assume the technician is competent for the task and does not
closely check the technician’s work, the overall likelihood for error increases to one in a
thousand, the same likelihood as that for the technician alone. Overall task reliability is now
99.9 percent. 35 System reliability is only as good as the weakest link, especially when human
beings become part of the system during work activities. The perception of another’s
capabilities influenced the supervisor’s decision not to check the technician’s performance—a
team error.
Several socially related factors influence the interpersonal dynamics among individuals on a
team. Because individuals are usually not held personally responsible for a group's performance,
some individuals in a group may not actively participate. Some people refrain from becoming
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Section 34
involved, believing that they can avoid answerability for their actions, or they “loaf” in group
activities.36 Team errors are stimulated by, but are not limited to, one or more of the following
social situations.
� Halo Effect – Blind trust in the competence of specific individuals because of their
experience or education. Consequently, other personnel drop their guard against error by the
competent individual, and vigilance to check the respected person's actions weakens or
ceases altogether. This dynamic is prevalent in hospital operating rooms, where members of
the operating teams often fail to stay vigilant and check the procedures and actions in
progress because a renowned surgeon is leading the team and there are several other sets of
eyes on the task at hand. Each year it is estimated that there are between 44,000 and about
90,000 deaths attributable to medical errors in hospitals, alone.37 Never mind the
transfusions of mismatched blood plasma, amputations of the wrong limbs, administration of
the wrong anesthesia, or issuance of the wrong prescriptions. It is the medical instruments,
sponges, towels, and the like left in patients’ bodies following surgery that are hard for
laymen to understand.
� Pilot/Co-Pilot – Reluctance of a subordinate person (co-pilot) to challenge the opinions,
decisions, or actions of a senior person (pilot) because of the person’s position in a group or
an organization. Subordinates may express “excessive professional courtesy” when
interacting with senior managers, unwittingly accepting something the boss says without
critically thinking about it or challenging the person’s actions or conclusions.38
Example of Pilot/Co-Pilot Error
A classic example of this dynamic occurred between the pilot and co-pilot of Air Florida Flight
90 at Washington’s National Airport in January 1982. The temperature was about 25 degrees. It
had snowed hard for some time while the plane sat on the ground during airport closure because
of weather. The aircraft had not properly been de-iced, and there was snow on the leading edges
of the wings as the flight crew prepared for takeoff. During the after-start checklist procedure,
the co-captain called out “engine anti-ice system.” And the captain reported, “engine anti-ice
system off,” and then failed to turn it on. The system should have been on. Consequently, ice
interfered with the engine pressure ratio (EPR) system, the primary indication of thrust being
developed by the engines. The co-pilot called the captain’s attention to the anomalous engine
indications at least five times in the last moments before the plane rotated off the runway, but he
did not oppose the captain’s decision to continue takeoff. Given the engine indications, he
should have insisted the takeoff be aborted. (All other engine parameters were later found to be
well below limit values.) The pilot thought the EPR settings were at the indicated limits when he
took off; in reality, the aircraft had only three-fourths of the necessary thrust in both engines.
The plane failed to achieve adequate lift. It hit the 14th Street Bridge and plunged nose down
into the freezing Potomac River, killing 74 of the 79 people on board. 39
� Free Riding – The tendency to “tag along” without actively scrutinizing the intent and
actions of the person(s) doing the work or taking the initiative. The other person takes
initiative to perform the task, while the free-riding individual takes a passive role in the
activity.
Section 35
Example of Free Riding Error
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
The water flushing of compound salts inside the transfer piping at the fertilizer and pesticide
plant in Bhopal, central India, was a routine task. The flushing operation was normally carried
out under the direction of a shift maintenance supervisor. On December 2, 1984, the
maintenance supervisor was called to another assignment, and the flush was carried out under
the direction of the operations supervisor. A new compound, methyisocyanate (MIC), was used
to produce the pesticide Sevin at the plant. MIC is unstable and highly reactive to water. The
procedure to ensure isolation of water from a MIC tank during piping flushes was to close the
valve to the tank, and then insert a slip blind (blank flange) into the piping to make sure that
water did not leak through the valve and enter a MIC storage tank. During the investigation of
the accident, an operator testified that he noticed the closed valve had not been sealed with a
slip blind (metal disc), but he said, “It was not my job to do anything about it.”40
� Groupthink – Cohesiveness, loyalty, consensus, and commitment to the team are all worthy
attributes of a team. However, at times, these characteristics can work against the quality of
team decisions. There can be a reluctance to share contradictory information about a
problem for the sake of maintaining the harmony of the work group. This is detrimental to
critical problem-solving. This dynamic can be made worse by one or more dominant team
members exerting considerable influence on the group's thinking (pilot/co-pilot or halo
effect). Consequently, critical information known within the group may remain hidden from
other team members. Groupthink can also result from subordinates passing on only “good
news” or “sugar-coating” bad news so as to not displease their bosses or higher level
managers. The symptoms of groupthink are as follows:
o Illusion of invulnerability – Creates excessive optimism and encourages extreme risk
taking.
o Collective rationalization – Discounts warnings that might lead to reconsidering
assumptions before recommitting to past decisions.
o Unquestioned morality – Inclines members to ignore the ethical or moral consequences of
decisions because of unquestioned belief in the group’s inherent morality.
o Stereotyped view – Characterizes the opposition as too evil for genuine negotiation or too
weak and stupid to effectively oppose the group’s purposes.
o Direct pressure – Discourages dissent by any member who expresses strong arguments
against any of the group’s stereotypes, illusions, or commitments that this type of dissent
is contrary to what is expected of loyal members.
o Self-censorship – Reduces deviations from the apparent group consensus reflecting each
member’s inclination to minimize to himself the importance of his doubts and counter
arguments.
o Illusion of unanimity – Shared by members with respect to the majority view (partly
resulting from self-censorship of deviations, augmented by a false assumption that silence
means consent).
o Self appointed mind-guards – Emerge from the members to protect the membership from
adverse information that might shatter their shared complacency about the effectiveness
and morality of their decisions.41
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Section 36
� Diffusion of Responsibility often causes a “risky shift” in decision-making and problem
resolution. It involves the tendency to gamble with decisions more as a group than if each
group member was making the decision individually42—responsibility is diffused in a group.
As the saying goes, “there is safety in numbers.” If two or more people agree together that
they know a better way to do something, they will likely take the risk and disregard
established procedure or policy. This has been referred to as a “herd mentality.”
Example of Diffusion of Responsibility Error
At a DOE production facility in the late 1980s, a shift manager in the operating contractor
organization, along with a small group of shift supervisors, planned and carried out the
replacement of a faulty pump over a weekend. This undertaking was performed to support the
startup of a system that had been shut down for an unusually long time. Operating within the
work control system to get the job done had not been successful. Continued reliance on that
system, the supervisory group reasoned, would not get a new pump in place, and the stream
would continue to be unusable. Faced with pressures to meet a “startup” schedule, and
frustrated with their inability to get work done through routine channels, the men took matters
into their own hands and did the work themselves. In so doing, the team violated numerous
procedures governing the work control system, in-process quality inspections, the worker
certification program, and the union labor rules governing work assignments and
responsibilities. No single salaried supervisor would have considered doing a union mechanic’s
job on his/her own. In a group situation, given the urgency, it seemed to make good sense. The
outcome for these men included days off without pay and a demotion for the shift manager.43
The following strategies tend to reduce the occurrence of team errors.
� Maintain freedom of thought from other team members.
� Challenge actions and decisions of others to uncover underlying assumptions.
� Train people on team errors, their causes, and intervention methods.
� Participate in formal team-development training.
� Practice questioning attitude/situational awareness on the job and during training.
� Designate a devil's advocate for problem-solving situations.
� Call “timeouts” to help the team achieve a shared understanding of plant or product status.
� Perform a thorough and independent task preview before the pre-job briefing.
Personal Dependencies
An unsafe personal dependency exists when an individual relies on his or her personal
experience, proficiency, or qualifications to maintain control. Because past practices have not
led to a problem, the individual becomes indifferent toward the need for care and attention.
Competence does not guarantee positive control. At the beginning of this chapter, “Traps of
Human Nature” and “Unsafe Attitudes” were discussed regarding their impact on human
fallibility. Such psychological and physiological factors can create unsafe personal dependencies
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
and lead to error. Of particular concern is overconfidence in one’s own ability at a critical step,
inhibiting the rigorous use of human performance tools. Overcoming personal dependencies
usually involves:
� training that addresses the limitations of human nature;
� promoting a culture that supports situational awareness and a questioning attitude;
Section 37
� reinforcing and coaching the proper application of human performance tools during in-field
observations; and
� improving the knowledge of risk-important equipment and critical steps.
PERFORMANCE MODES (Essential Reading)
Information Processing, Memory, and Attention
Cognition is the mental process of knowing. It is our mental activity encompassing perception,
mental imagery, thinking, remembering, problem solving, decision-making, learning, language,
and conscious direction of motor activities. Cognitive psychology is the study of how we
process information from our environment; how we attend to, perceive, process, and store
information; and how we retrieve and act on information from memory. To better anticipate and
prevent error, we need to better understand how people process information. Psychologists have
explained memory in terms of three basic components. Refer to the graphic below on
information processing and memory:
� Sensory Memory – Each sensory system, (sight, touch, smell, taste, and hearing) has
corresponding sensory memory, or sensory register, or store. Each sensory memory briefly
stores and transforms the stimuli it receives into a form that can be processed by short-term
memory. All incoming information is not processed. Information that is not “attended to”
decays or is “overwritten” by new incoming stimuli.
� Short-Term Memory – Short-term memory (STM) receives, holds, and processes
information from the sensory memory. Processing in STM is necessary before information
can be transferred and retained in long-term memory. Short-term or “working” memory has
limited storage capacity, as the name implies. Information entering short-term memory
“decays” after about 12 to 30 seconds, unless it is “rehearsed” or otherwise consciously
attended to and encoded for transfer into long-term memory. STM also retrieves information
from long-term memory when needed.44
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Short-Term
Sensory
Store
Responses
Short-
Term or
Working
Memory
Stimuli:
sight
hearing
smell Perception
Long-Term
Memory
Decision and
Response
Selection
Response
Execution
Attention
Resources
Information Processing and Memory
� Long-Term Memory – Long-term memory (LTM) receives information from short-term
memory and stores it indefinitely. LTM capacity is considered unlimited for practical
purposes. LTM holds all of the learning and memory of our life experience. Information
that is stored in long-term memory is retrieved by short-term memory to support recall and
recognition.
The shared Attention Resources depicted in the model by Wickens (see footnote 43), above,
enables the mind to attend to information while performing one or more tasks (such as driving a
car and talking with a passenger at the same time).45 How much attention is required to perform
satisfactorily defines the mental workload for an individual, as some tasks require more attention
than others.46 Knowledge, skill, and experience with a task decrease the demand for attention.
Humans control their actions through various combinations of two control modes—the conscious
and the automatic. The conscious mode is restricted in capacity, slow, sequential, laborious,
error-prone, but potentially very smart. This is the mode we use for ‘paying attention’ to
something. It is needed for handling entirely novel problems, trained-for problems, or problems
for which procedures have been written.
Section 38
The automatic mode of control is the opposite in all respects. It is largely unconscious. The
automatic mode is seemingly limitless in its capacity. It is very fast and operates in parallel; that
is, it does many things at once rather than one thing after another. It is effortless and essential
for handling the recurrences of everyday life—the highly familiar, everyday situations. But it is
a highly specialized community of knowledge structures. It knows only what it knows; it is not a
general problem-solver, like consciousness.47
We do not experience reality exactly as it exists, but as our experience and memories cause us to
perceive it. Our sensory systems detect and take in stimuli from the environment in the form of
physical energy. Each sensory receptor type is sensitive to only one form of energy. These
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
receptors convert this energy into electrochemical energy that can be processed by the brain.
However, our perception involves more than the receipt of sensory information. We must attend
to, select, organize, and interpret this information to meaningfully recognize objects and events
in our environment. Our interpretation of sensory information requires retrieval from long-term
memory. Our prior experience and knowledge, emotional state, and value system (including
prejudices) determine our perceptions.48
In summary, the information-processing model depicts sensory stimuli entering short-term
sensory store, where they are transformed into a form that the perceptual processes within the
brain can understand. Processed stimuli are transferred to working memory. Working memory
draws upon and interacts with long-term memory to develop our perception of the world and to
determine our response to these perceptions.49 The retrieval and processing of long-term
memories by STM enable us to function in the world.
Although the brain is designed for information transfer, sometimes it fails.50 Error is a function
of how the brain processes information related to the performance of an activity. When people
err, there is typically a fault with one or more of the following stages of information processing.
� Sensing – Visual, audible, and other means to perceive information in one's immediate
vicinity (displays, signals, spoken word, or cues from the immediate environment).
Recognition of information is critical to error-free performance.
� Thinking – Mental activities involving decisions on what to do with information. This stage
of information-processing involves interaction between one's working memory and long-term
memory (capabilities, knowledge, experiences, opinions, attitudes).
� Acting – Physical human action (know-how) to change the state of a component using
controls, tools, and computers; includes verbal statements to inform or direct others.51
� Attention – Determines what information is transmitted to the mind’s working (short-term)
memory. The amount of stimuli that can be taken in by our sensory systems is considered to
be unlimited. However, the amount of information that can be held in working memory is
limited to 7 + 2 items.52 Working memory therefore, creates a “bottleneck” for incoming
information. In a sense, it is a bottleneck with a purpose—otherwise we would be inundated
with irrelevant stimuli.
Attention is also influenced by the following:
Section 39
� Expectancy – We direct our sensory receptors—eyes, ears, nose, fingers to where we
anticipate locating information within our environment. Surprise occurs when events differ
from our expectations.
� Relevance – We seek information/stimuli relevant to our immediate tasks and our goals.53
Our attention constantly shifts as a result of voluntary direction (internal) or automatically as a
result of attention attracting stimuli (external) in the environment. Our focus of attention results
from whether a stimulus activates top-down (internal) or bottom-up (external) processes.
� Top-Down – Attention control is conscious direction, using information residing in memory
stores. It is also termed concept-driven or effortful attention. Top-down attention is
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
purposefully directed and is influenced by expectancy and relevance, as well as prior
knowledge and experience. Examples are a search task, such as when looking for the face of
a friend in the crowd, seeking a specific item on a control display, or conducting a parts
inspection. Top-down attention is slower than bottom-up attention.
� Bottom-Up – Attention is captured by external stimuli, usually unexpected events or
salience. This is also termed data-driven or automatic attention. Examples are a bright flash
of light, a loud sound, loss of balance due to slippery conditions, or impact by an object.
Bottom-up attention is very rapid, reaching its maximum 100-200 milliseconds after stimulus
perception.54
Inattention to detail is an often-cited cause of human performance problems. Avoiding error is
not as simple as telling someone to “pay attention.” First of all, attention is a limited
commodity; second, we can only attend to a very small proportion of the available sense data
and; third, unrelated matters can capture our attention. 55 There are three attention modes.
Attention can be focused, divided, or selective. If attention is focused, something has to be
ignored. If attention is strongly drawn to one particular thing it is necessarily withdrawn from
other competing concerns. Divided attention involves paying attention to two or more sources of
information on a time-share basis, similar to using a flashlight in a dark room trying to see two
different items, moving the flashlight back and forth. Divided attention can be dangerous; for
example, a driver's attention is significantly distracted while using a cell phone.56 Selective
attention means an individual gives preference to distinct information, such as one's name in a
noisy meeting room. It is impossible for humans to pay attention to everything all the time. This
can lead to the occasional error.57 The likelihood of error is enhanced when someone attempts to
do more than one activity in one stage of information processing (sensing, thinking, acting), such
as listening to the radio and a passenger simultaneously while driving an automobile. This is
why it is so important to control the environment in which people work by minimizing
interruptions and distractions or other stimuli that can negatively affect a performer’s attention
capabilities. Trained, experienced operators can consciously attend to a maximum of two or
three channels of information (such as flow, temperature, pressure) and still be effective.58
Beyond that, error is likely due to limited attention resources of human nature.
Section 40
Jens Rasmussen developed a classification of the different types of information processing
involved in industrial tasks. This influential classification system is known as the Skill, Rule,
Knowledge based (SRK) approach (p. 22). Rasmussen’s scheme suggests a useful framework
for identifying the types of error likely to occur in different operational situations, or within
different aspects of the same task where different types of information processing demands on
the individual may occur. The terms skill, rule, and knowledge based information processing
refer to the degree of conscious control exercised by the individual over his or her activities.
Tasks individuals perform every day on the job vary from doing a lot and thinking a little to
thinking a lot and doing a little. Depending on the situation, as perceived by the individual, he or
she will conduct work according to the level of performance that seems adequate to control the
situation. The level of performance is a function of the familiarity an individual has with a
specific task and the level of attention (information processing) a person applies to the activity.
2-19
None
No
Yes
No
YesNo
Yes
Subsequent Attempts
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
Problem solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Skill based
Performance
Rout ne actions in a
familiar s tuation
Rule based
Performance
Pre-packaged act ons
determne by
recognition of familiar
prob em s tuat ons
Knowledge-
based
Performance
Ana ys s of unfamiliar
prob em s tuat on
us ng stored knowedge
Source Reason (1990) and Rasmussen (1981)
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
Problem solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
Problem solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
Problem solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
Problem solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
Section 41
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
Problem solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
Select problem solution:
Problem solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
Problem solving mode:
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Example Uses of Performance Levels
The three performance levels can be readily applied to a familiar activity like driving an
automobile. For an experienced driver, the control of speed and direction of the vehicle occur
almost entirely at the skill-based level (an automatic mode of control). Things related to how the
driver relates to other drivers on the road are covered by rules (speed limit, distance from other
cars, right of way, etc.) of the kind if (situation X occurs) do—or don’t do—(action Y). Here the
driver is in a rule-based level of performance. While traveling at a good clip along a main
highway, the driver hears on the radio that there is a traffic jam up ahead. To continue will result
in long delays. So the driver has to use his/her knowledge of directions and road connections
and accesses to find an alternative route. This problem-solving ”mind-work”’ occurs at the
knowledge-based level (conscious mode) .59
Generic Error Model System (GEMS)
The GEMS model illustrates how humans make use of information processing for a particular
task and how they move from one performance level to another as they complete a task. The
flowchart illustrates the distinctions between the three levels of performance.60 How GEMS is
applied can be illustrated by an example.
Example Application of GEMS
A process worker is monitoring a
control panel in a batch processing
plant. The worker executes a series of
routine operations such as opening and
closing valves and turning on agitators
and heaters. Since the worker is highly
practiced, he is carrying out the valve
operations in an automatic skill-based
manner, only occasionally monitoring
the situation at the points indicated by
the “OK?” boxes at the skill-based
level. If one of these checks indicates
that a problem has occurred, perhaps
indicated by an alarm, the worker then
enters the rule-based level to determine
the nature of the problem. This may
involve gathering information from
various sources such as dials, chart
recorders, and VDU screens, which is
then used as input to a diagnostic rule
of the following form: <IF> symptoms
are X <THEN> cause of the problem is
Y. Having established a plausible cause
of the problem on the basis of the
pattern of indications, an action rule
may then be invoked of the following
Section 42
-
-
i
i
-
i
i
l i i
l i
l i i
i l
:
None
No
Yes
No
YesNo
Yes
Subsequent Attempts
-
Skill-based
Performance
Routine actions in a
familiar situation
Rule-based
Performance
Pre-packaged actions
determine by
recognition of familiar
problem situations
Knowledge-
based
Performance
Analysis of unfamiliar
problem situation
using stored knowledge
Source: Reason (1990) and Rasmussen (1981)
None
No
Yes
No
YesNo
Yes
None
No
Yes
No
YesNo
Yes
Subsequent Attempts
-
Skill-based
Performance
Routine actions in a
familiar situation
Rule-based
Performance
Pre-packaged actions
determine by
recognition of familiar
problem situations
Knowledge-
based
Performance
Analysis of unfamiliar
problem situation
using stored knowledge
Source: Reason (1990) and Rasmussen (1981)
Subsequent Attempts
-
Skill-based
Performance
Routine actions in a
familiar situation
Rule-based
Performance
Pre-packaged actions
determine by
recognition of familiar
problem situations
Knowledge-
based
Performance
Analysis of unfamiliar
problem situation
using stored knowledge
Subsequent Attempts
-
Subsequent Attempts
-
Subsequent AttemptsSubsequent Attempts
Select problem solution:
Develop corrective action. Apply to
problem situation. Observe results.
--Problem-solving mode:
Recall mental model. Apply observed
symptoms and fundamental principles
to update mental model.
THEN:
Apply known action.
Solved?
Is task
proceeding
OK?
Is task
proceeding
OK?
Identify available
symptoms
IF:
familiar
situation?
Identify available
symptoms or other
familiar analogy
Recognize
problem
situation
Skill-based
Performance
Routine actions in a
familiar situation
Rule-based
Performance
Pre-packaged actions
determine by
recognition of familiar
problem situations
Knowledge-
based
Performance
Analysis of unfamiliar
problem situation
using stored knowledge
Skill-based
Performance
Routine actions in a
familiar situation
Rule-based
Performance
Pre-packaged actions
determine by
recognition of familiar
problem situations
Knowledge-
based
Performance
Analysis of unfamiliar
problem situation
using stored knowledge
Source: Reason (1990) and Rasmussen (1981)
2-20
Familiarity (w/ task)Low High
High
Low
A
tte
nt
io
n
(to
ta
sk
)
SB
KB
RBIf - Then
Auto
Patterns
Inattention
Misinterpretation
Inaccurate
Mental Picture
Δ
?
SB
KB
RBIf - Then
Auto
Patterns
Δ
?
SB
KB
RBIf - Then
Auto
Patterns
SB
KB
RBIf - Then
Auto
Patterns
SB
KB
RBIf - Then
Auto
Patterns
Δ
?
Department of Energy Human Performance Handbook Chapter 2 Reducing Error
form: <IF> the cause of the problem is Y <THEN> do Z. If, as a result of applying the action
rule, the problem is solved, the worker will then return to the original skill-based sequence. If
the problem is not resolved, then further information may be gathered in order to try to identify a
pattern of symptoms corresponding to a known cause. If the cause of the problem cannot be
established by applying any available rule, the worker may then have to revert to the knowledge-
based level. It may become necessary to utilize chemical or engineering knowledge to handle
the situation.
As shown in the above example, uncertainty declines as knowledge about a situation improves
(learning and practice). Consequently, familiarity (knowledge, skill, and experience) with a task
will establish the level of attention or mental functions the individual chooses to perform an
activity. As uncertainty increases, people tend to focus their attention to better detect critical
information needed for the situation. People want to boost their understanding of a situation in
order to respond correctly.62
Section 43
Skill-Based
Performance
HiHiHiHiHiHigggggghhhhhh
Skill-based performance
involves highly practiced,
largely physical actions in
very familiar situations in
Misinterpretation
Inaccurate
Mental Picture
Misinterpretation
Inaccurate
Mental Picture
M
SB
KB
RBIf - Then
Aut
Patterns
isinterpretation
Inaccurate
Mental Picture
Misinterpretation
Inaccurate
Mental Picture
Δ
?
LowLowLowLowLowLow
which there is little conscious
monitoring. Such actions are
usually executed from
memory without significant
conscious thought or attention
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processed with little or no allocation of attention resources is called automatic processing. When
skills are learned to the point of being automatic, the load on working memory typically is
reduced by 90 percent.64 This occurs after extensive practice of a task so that, literally, it can be
performed “without thought.” Many actions in a typical day are controlled unconsciously by
human instinct, such as keyboarding, writing one’s signature, taking a shower, driving a car. In
the skill-based mode, the individual is able to function very effectively by using pre-programmed
sequences of behavior that do not require much conscious control. It is only occasionally
necessary to check on progress at particular points when operating in this mode. 65
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Examples of Skill-Based Activities
Examples of skill-based activities for well-trained and practiced individuals include:
� mowing the lawn;
� using a hammer or other hand tool;
� controlling various processes manually (such as pressure and level),
� hanging a tag;
� analyzing chemical composition of a routine sample;
� performing repetitive calculations;
� using measure and test equipment;
� opening a valve;
� taking logs; and
� replacing parts during maintenance.
Error Modes are the prevalent ways, not the only ways, people err for the particular
performance mode. Error modes are generalities that aid in anticipating and managing error-
likely situations aggravated by inattention, misinterpretation, and inaccurate mental models.
Skill-Based Error Mode – Inattention
The error mode for skill-based performance is inattention. Skill-based errors are primarily
execution errors, involving action slips and lapses in attention or concentration. Errors involve
inadvertent slips and unintentional omissions triggered by simple human variability or by not
recognizing changes (note the Δ symbol on the above chart) in task requirements, system
response, or facility conditions related to the task. Some examples of errors committed while in
the skill-based performance level follow.
� When addressing an envelope, he put his old address in the return box instead of his new
(correct) address.
� She forgot to drop off shoes at the shoe shop to be repaired, and instead drove right past the
shoe shop and straight to her home.
Section 44
� An electrician had been asked to change a light bulb that indicated whether a hydraulic on/off
switch was selected. The hydraulic system was being worked on, and the electrician was
aware that it would be unsafe to activate the system. Nevertheless, after changing the bulb,
and before he had realized what he was doing, he had followed his usual routine and pushed
the switch to the ”on” position to test whether the light was now working.
� Intending to shut down lines A and B, the operator also pressed the “shut-off’“ control
buttons for lines C and D.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Under ideal conditions, the chance for error is less than 1 in 10,000, according to a study in the
nuclear power industry.66 People most often possess an accurate understanding of the task and
have correct intentions. Roughly 90 percent of a person's daily activities are spent in the skill-
based performance mode.67 However, only 25 percent of all errors are attributable to skill-based
errors in the nuclear power industry.68 Potentially, a person can be so focused on a skill-based
task that important information in the work place is not detected.69 Another concern for skill-
based tasks is that people are familiar with the task. The greater the familiarity, the less likely
perceived risk will match actual risk. People become comfortable with risk and eventually grow
insensitive to hazards.70 Several tools in the HPI Handbook volume 2 are designed to help
anticipate, prevent or catch skill-based errors ( task preview, job-site review, questioning
attitude, stop when unsure, self-checking, pre-job briefing, place-keeping, peer check and
concurrent verification)*6.
Rule-Based Performance
People switch to the rule-based performance level when they notice a need to modify their
largely pre-programmed behavior because they have to take account of some change in the
situation. The work situation has changed such that the previous activity (skill) no longer
applies. This problem is likely to be one that they have encountered before, or have been trained
to deal with, or which is covered by the procedures. It is called the rule-based level because
people apply memorized or written rules. These rules may have been learned as a result of
interaction with the facility, through formal training, or by working with experienced workers.
The level of conscious control is between that of the knowledge- and skill-based modes. The
rule-based level follows an IF (symptom X), THEN (situation Y) logic. In applying these rules,
we operate by automatically matching the signs and symptoms of the problem to some stored
knowledge structure. So, typically, when the appropriate rule is applied, the worker exhibits pre
packaged units of behavior. He/she may then use conscious thinking to verify whether or not
this solution is appropriate.71
The goal in rule-based performance is to improve one's interpretation of the work situation so
that the appropriate response is selected and used.72 This is why procedures are prepared for
situations that can be anticipated. Procedures are pre-determined solutions to possible work
situations that require specific responses. Rules are necessary for those less familiar, less
practiced work activities for which a particular person or group is not highly skilled. Not all
activities guided by a procedure are necessarily rule-based performance. In normal work
situations, such activities are commonly skill-based for the experienced user.
Section 45
Examples of Rule-Based Activities
Examples of rule-based activities include:
� deciding whether to replace a ball bearing inspected during preventive maintenance;
� responding to a control board alarm;
*6 The primary tool suggested for skill based work is self check.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
� estimating the change in tank level based on a temperature change (thumb rules);
� feeling equipment for excessive vibration or temperature on operator rounds;
� performing radiological surveys;
� using emergency operating procedures; and
� developing work packages and procedures.
Rule-Based Error Mode
Since rule-based activities require interpretation using an if-then logic, the prevalent error mode
is misinterpretation. People may not fully understand or detect the equipment or facility
conditions calling for a particular response. Errors involve deviating from an approved
procedure, applying the wrong response to a work situation, or applying the correct procedure to
the wrong situation.73 Examples of errors committed when working in the rule based
performance level include the following.
� A driver was about to pull out into the traffic flow following a stop at the side of the road.
He checked the side-view mirror and saw a small green car approaching. He briefly checked
his rear-view mirror (which generally gives a more realistic impression of distance) and
noted a small green car some distance away. He then pulled out from the shoulder of the
road and was nearly hit by a small green car. There were two of them, one behind the other.
The driver assumed they were one and the same car. The first car had been positioned so that
it was only visible in the side-view mirror.
� The technician knew that normal tire pressures in automobile tires is 32-35 psi. So, when he
was required for the first time to air up a smaller, temporary-use automobile tire, he filled the
tire to the customary 35 lbs. In actuality, small-diameter, temporary-use tires are aired up to
55-60 psi.
� A northbound commuter train in London in 1988 ran into the back of a stationary train after
having passed a green signal. Thirty-five people died and 500 were injured. The signal light
had given the wrong signal because the old signal wires had come into contact with nearby
equipment for the new signal system that caused a wrong-side signal failure. The light should
have shown red, for stop. The electrician who had wired the signal on the new system just
the day before the accident had never been properly trained. He failed to cut off or tie back,
and then insulate, old wires as he wired in the new signal system. He merely bent old wires
back out of the way. The untrained technician had learned bad habits on his own that became
his “strong but wrong rules.” His application of a bad rule went uncorrected. 74
The chance for error increases when people make choices or decisions, especially in the field.
Rule-based and knowledge-based performance modes involve making choices. With less
familiarity for the activity, the chance for error increases to roughly 1 in 1,000.75 In terms of
reliability, this is still very good (99.9 percent). In the nuclear power industry, studies have
shown that roughly 60 percent of all errors are rule-based.76 HPI Handbook volume 2 includes
tools to help anticipate, prevent or catch rule-based errors. They include for example: task
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Section 46
Department of Energy Human Performance Handbook Chapter 2 Reducing Error
preview, procedure adherence, pre-job briefing, questioning attitude, peer-checking and
concurrent verification among others.*7
Knowledge-Based Performance
Warning; the terminology of knowledge-based performance can be confusing! It is tempting to
think that much of the engineering design work and the scientific investigations and research at
DOE laboratories falls in the knowledge based category – simply because such work is
performed by highly knowledgeable people. We must however at all costs avoid the temptation
to shrug off the essential nuances and simply argue that since we do research or one of a kind
work, and our people are highly educated and skilled, then our work is knowledge based. The
truth is quite the opposite. The situation described as “knowledge based mode” might better be
called “lack of knowledge” mode.
Knowledge based work, as defined by Rasmussen, generally means that we don’t really
understand what we are doing. Clearly, that is not the case with most DOE work. Even in the
most cutting edge science, the ability to develop and conduct controlled experiments depends on
control; keeping the uncontrolled variables as few as possible so that we may observe the results
of the experiment in order to hypothesize, test theories and ultimately develop new knowledge. It
in fact might be argued that the accomplished researcher has highly refined abilities to work in
skill and rule modes in order to be able to work in knowledge mode, since working in knowledge
mode is so difficult.
Not all hazards, dangers, and possible scenarios can be anticipated in order to develop
appropriate procedures. Even training is unable to anticipate all possible situations that can be
encountered. There are some situations in which no procedure guidance exists and no skill
applies. Dr. James Reason concludes that the knowledge-based level of performance is
something we come to very reluctantly. Humans only resort to the slow and effortful business of
thinking things through on the spot after they have repeatedly failed to find some pre-existing
solution.
Hence, knowledge-based behavior is a response to a totally unfamiliar situation (no skill or rule
is recognizable to the individual The person must rely on his or her prior understanding and
knowledge, their perceptions of present circumstances, similarities of the present situation and
similarities to circumstances encountered before , and the scientific principles and fundamental
theory related to the perceived situation at hand.77 People enter a knowledge-based situation
when they realize they are uncertain (see the ? symbol on previous chart) about what to do. If
uncertainty is high, then the need for information becomes paramount.78 To effectively gain
information about what we are doing or about to do, our attention must become more focused.79
Knowledge-based situations are puzzling and unusual to the individual. Often our understanding
of the problem is patchy, inaccurate, or both. In many cases, information sources contain
conflicting data, too much data, or not enough data, amplifying the difficulty of problem-solving.
Additionally, consciousness is very limited in its capacity to hold information, storing no more
*7 The primary tools suggested for rule based work are procedure use and adherence.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Section 47
than two or three distinct items at a time. Consciousness tends to behave like a leaky sieve,
allowing things to be lost as we turn our attention from one aspect of the problem to another.80
Because uncertainty is high, knowledge-based tasks are usually stressful situations.
Examples of Knowledge-Based Activities
Knowledge-based activities involve problem-solving. Such situations require the use of
fundamental knowledge of processes, systems, and so on—“thinking on your feet.” Examples of
common problem-solving situations include the following:
� troubleshooting;
� performing an engineering evaluation of a new design;
� reviewing a procedure for ‘intent of change;’
� resolving conflicting control board indications;
� holding meetings to address problems;
� conducting scientific experiments;
� resolving human performance problems;
� planning business strategies, goals, and objectives;
� performing root cause analysis of events;
� conducting trend analyses;
� designing equipment modifications;
� making budget allocation decisions
� allocating resources;
� changing policies and expectations; and
� performing an engineering calculation.
Knowledge-Based Error Mode
Knowledge-based activities require diagnosis and problem-solving. There are considerable
demands on the information-processing capabilities of the individual that are necessary when a
situation has to be evaluated from first principles. It is not surprising that humans do not perform
very well in high stress, unfamiliar situations where they are required to ‘think on their feet’ in
the absence of rules, routines, and procedures to handle the situation.81 People tend to use only
information that is readily available to evaluate the situation. Also, problem solvers often
become over-confident in the correctness of their knowledge; an “I know I’m right” effect. They
also become enmeshed in one aspect of the problem to the exclusion of all other considerations.82
Decision-making is erroneous if problem-solving is based on inaccurate information. Often,
decisions are made with limited information and faulty assumptions. Consequently, the
prevalent error mode is an inaccurate mental model of the system, process, or facility status.
Under such circumstances, the chance for error is particularly high, approximately one in two (50
percent) to one in ten.83 In the nuclear power industry, studies indicate that roughly 15 percent
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
of all errors are knowledge-based.84 HPI Handbook volume 2 provides several tools to help
anticipate, prevent, or catch knowledge-based errors. They include, for example, technical task
pre-job briefing; project planning; problem-solving; decision-making; and peer review.
How Performance Modes Can be Used
Section 48
A better contextual understanding of individuals’ conscious and automatic behaviors as
described in the skill, rule, and knowledge performance modes, and knowing the kinds of errors
individuals tend to make while working in those various modes, can be extremely useful.
Managers responsible for establishing and maintaining effective controls can make good use of
this information. Workers need accurate, complete, and unambiguous procedures and guides for
reference when doing rule-based work. They may also need access to a subject matter expert
when making choices about the rules to select and for correct application of those rules.
Workers performing skill-based work need adequate tools to minimize action slips, and they
need to be free from interruptions and distractions that aggravate concentration, divide their
attention, and contribute to lapses in memory that cause error. When working in skill-based
performance mode, workers may benefit from simple job aids and reminders. On the other hand,
for individuals working in the knowledge-based mode, where their understanding of the problem
is often patchy, or inaccurate, or both, and where the slow and effortful business of thinking
things through is needed, collaboration with a small team of thoughtful, committed, and
experienced individuals is needed to help in problem-solving and decision-making. Individuals
performing work in any of the performance modes can benefit from the use of the error-
reduction tools addressed later in this chapter.
When errors and mistakes of consequence occur that indicate some corrective action is needed to
minimize recurrence, knowing the work processing method or performance mode the individual
was working in is instructive. All too often, workers involved in skill-based performance who
err are scheduled for retraining as a logical solution. But, retraining workers to do work that is
already basically memorized and automatic, performed with little conscious thought because of
the nature of the work, is a waste of time and is an insult to the worker. It is very hard to train a
worker not to repeat something he or she did not intend to do in the first place. Training is not
the solution in these instances. Observations of work can be very beneficial. People don’t
always know why something went wrong.
Observations are used to gather data about the worker behaviors, the job-site conditions, and
organizational support that may have been wanting. Inadequate tools, incomplete work
packages, scheduling conflicts, poorly written procedures, excessive noise, extreme heat or cold,
poor lighting, and so on, may be contributing factors to poor performance. Some one-on-one
time with the individual may be in order. The purpose is to learn of the circumstances
surrounding the slip, trip, or lapse and what, if anything, can be changed in the work
environment or with the individual to eliminate a similar reoccurrence. The error may have been
provoked by fatigue and stress; the worker may have lost sleep worrying about a teenager who
left home. It may be that the worker has become complacent and was careless. Distractions and
interruptions may have disrupted the worker’s concentration and that led to the error. Those
conditions can be controlled.
Errors that occur when working in rule-based performance may be corrected through retraining.
Generally, the worker has misinterpreted a requirement or a “rule.” He or she has applied a bad
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Section 49
Department of Energy Human Performance Handbook Chapter 2 Reducing Error
rule to a given application; or, conversely, has used a good rule in a wrong application. In these
instances, understanding requirements and knowing where and under what circumstance those
requirements apply is cognitive in nature and must be learned or acquired in some way. Rule-
based errors can be caught or mitigated by individuals exhibiting a questioning attitude, by
calling a time out, or by stopping work when they are unsure. Peer checks can also be used to
stop someone from committing a consequential error.
Corrective action to reduce knowledge-based mistakes is more complicated. An analysis of what
went wrong will need to be carried out to formulate a corrective action. It may be that the
person’s understanding and knowledge of the system and the scientific principles and
fundamental theory related to the system were inadequate. Training or retraining could help. It
may be that people’s technical knowledge was adequate, but that the three individuals working
on the problem lacked problem-solving skills, fell victim to team errors, or failed to effectively
communicate with each other in order to solve the problem. Perhaps the team could not make
good decisions in an emergency. Coaching is a pro-active solution to helping individuals
eliminate error when working in any performance mode, but is particularly adept for knowledge-
based performance modes. Peer-evaluations are also effective in this instance.
Mental Models
A person handles a complex situation by simplifying the real system into a mental image he/she
can remember (such as a simple one-line drawing). A mental model is the structured
understanding of knowledge (facts or assumptions) a person has in his or her mind about how
something works or operates (for example, facility systems).85,86 Mental models are used in all
performance modes. In fact, mental models give humans the ability to detect skill-based slips
and lapses. They aid in detecting deviations between desired and undesired system states, such
as manually controlling tank water level.87 A mental model organizes knowledge about the
following.
• what a system contains • how components work as a system
• why it works that way • current state of a system
• fundamental laws of
nature
An individual’s mental model may reflect (1) the true state of the system, (2) a perceived state of
the system, or (3) the expected state of the system that is developed through training and
experience with the system and recent interactions with the system. Note that all mental models
are inaccurate to some extent88 because of the limitations of human nature.
It is important to remember that knowledge-based performance involves problem-solving, and
mental models should be considered explicitly when a team works on a problem.89 Team
members should agree with the model they intend to use to diagnose and solve a problem.
Otherwise, misunderstandings and assumptions may occur. Frequent time-outs can help teams
keep mental models up to date.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Assumptions
Section 50
Knowledge-based situations can be stressful, anxious situations. Assumptions reduce the strain
on the mind, allowing a person to think without excessive effort. Assumptions are necessary at
times to help constrain a problem. Consequently, assumptions tend to occur more often when
people experience uncertainty, leading to trial-and-error and cause-and-effect problem-solving
approaches. Assumptions also occur as an outgrowth of unsafe attitudes and inaccurate mental
models. Statements such as “I think ...,” “We've always …,” or “I believe ...” are hints that an
assumption has been or is being made. These phrases are known as “danger words.” Inaccurate
mental models, in turn, can promote erroneous assumptions that may lead to errors.
Often, assumptions are treated as fact. Challenging assumptions is important in improving
mental models, solving problems, and optimizing team performance. Assigning a devil’s
advocate in a critical problem-solving situation may be worthwhile to achieve a better solution.
Also, challenging assumptions helps detect unsafe attitudes and inaccurate mental models. A
devil’s advocate can challenge assumptions using the following process.90
� Identify conclusion(s) being made by another person or yourself.
� Ask for or identify the data that leads to the conclusion(s). “How did you get that data?”
“What is the source of your concern?”
� Ask for the reasoning (mental model) that connects the data with the conclusion. “Do you
mean…?” “Why do you feel that way?”
� Infer possible beliefs or assumptions.
� Test the assumption with the other person. “What I hear you saying is…”
Mental Biases – Shortcuts
Humans tend to seek order in an ambiguous situation and to seek patterns they recognize.
Mental biases, or mental shortcuts, offer the human mind several unconscious methods to create
order and simplicity amid uncertainty, reducing mental effort.91 Personnel should be aware of
the potential for error that mental biases and mental shortcuts create during problem-solving and
decision-making, such as troubleshooting and diagnostics during emergency operation. More
will be said about underlying unconscious assumptions and taken-for-granted beliefs in the
opening pages of Chapter 5 on organizational culture. In some form or another, all humans use
mental biases. Biases were discussed earlier in this chapter with respect to the limitations of
human nature and include the following, among others:
� confirmation bias;
� similarity bias;
� frequency bias;
� availability bias;
� representative bias; and
� framing bias.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Conservative Decisions
To be conservative means to be cautious and protective of what is truly important—safety,
reliability, quality, security, and so on. It is an attitude that operational and personnel safety
must be protected regardless of current schedule and production pressures. In light of the
limitations of human nature, it makes sense to be conservative, especially when a decision
potentially affects operational or personnel safety. Who knows what information is missing or
what data was not considered? A systematic, team-based approach is called for so that safety
considerations are not compromised. In several INPO documents related to conservative
decision-making, the following factors are repeatedly mentioned as important to success in
making conservative decisions.
Section 51
� Recognize conditions that could challenge safety and reliability.
� Place structures, systems, and components in a known safe condition when uncertain.
� Seek prompt assistance from persons with relevant expertise.
� Avoid hasty decisions and hurried actions.
� Assign roles and responsibilities.
� Explore and evaluate alternatives rigorously, asking challenging questions to confirm
technical assumptions.
� Understand the potential consequences to safety and reliability of various alternatives.
� Adopt a deliberate and carefully controlled approach.
� Make a deliberate decision, providing clear direction, roles and responsibilities,
contingencies, and abort criteria.
� Do not proceed in the face of uncertainty.
ERROR-LIKELY SITUATIONS (Essential Reading)
Error-likely situations are defined as: A work situation in which there is
greater chance for error when performing a specific action or task in the
presence of error precursors.1
The second principle of human performance states: “error-likely situations are predictable,
manageable, and preventable.” An error-likely situation comes into play when task-related
factors exceed the capabilities of the individual, creating a mismatch at the point when the
individual is “touching” either the physical or the paper plant.92 The simple presence of adverse
conditions cannot be error-likely unless a specific action is to occur within that set of adverse
conditions. The elements of error likely situations appear in the graphic below.
2-30
Degree of mismatch due to
error precursors
Error likely Situation
unintentional
deviation from
preferred behavior
Job Site Conditions
• task
• individual
Department of Energy Human Performance Handbook Chapter 2 Reducing Error
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Job Site Conditions
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Error Precursors
Error precursors are unfavorable conditions embedded in the job site that create mismatches
between a task and the individual. Error precursors interfere with successful performance and
increase the probability for error.93 Simply stated, they are conditions that provoke error. They
can be organized into one or more of the following four categories.94
� Task Demands – Specific mental, physical, and team requirements to perform an activity
that may either exceed the capabilities or challenge the limitations of human nature of the
individual assigned to the task. Task demands include physical demands, task difficulty, and
complexity. Examples include excessive workload, hurrying, concurrent actions, unclear
roles and responsibilities, and vague standards.
� Individual Capabilities – Unique mental, physical, and emotional characteristics of a
particular person that fail to match the demands of the specific task. This involves cognitive
and physical limitations. Examples are unfamiliarity with the task, unsafe attitudes, level of
education, lack of knowledge, unpracticed skills, personality, inexperience, health and
fitness, poor communication practices, fatigue, and low self-esteem.
Section 52
� Work Environment – General influences of the workplace, organizational, and cultural
conditions that affect individual behavior. These include distractions, awkward equipment
layout, complex tagout procedures, at-risk norms and values, work group attitudes toward
various hazards, work control processes, and temperature, lighting, and noise.
� Human Nature – Generic traits, dispositions, and limitations that may incline individuals to
err under unfavorable conditions such as habit, short-term memory, stress, complacency,
inaccurate risk perception, mind-set, and mental shortcuts.
Error precursors are, by definition, prerequisite conditions for error and, therefore, exist before
an error occurs. If discovered and removed, job-site conditions can be changed to minimize the
chance for error. This is more likely if people possess an intolerance for error precursors or error
traps. Examples include reporting an improperly marked valve or a malfunctioning gauge in a
safety system, taking a broken ladder out of service, immediately cleaning up an oil spill,
stopping work until a change can be made to the procedure, calling in a replacement to relieve a
worker who has become ill, seeking technical help when unsure, asking for a peer review on
engineering calculations, routinely performing safety self-assessments, and so on.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
Common Error Precursors
Error precursors are not mysterious or obscure. To the contrary, they are noticeable, even
obvious, if people look for them. The error precursors listed below (in order of impact) were
compiled from a study of INPO's event database and from human performance, ergonomics, and
human factors sources. These are the more common conditions associated with events triggered
by human error. Some organizations distribute a plastic-coated error precursor card to their front
line workers to carry with them on the job. Workers refer to these cards during pre-job briefings
to help identify precursors related to the upcoming task. A more extensive list of error
precursors and error precursor descriptions is provided in Attachments A and B of this chapter.
Task Demands Individual Capabilities
1. Time Pressure (in a hurry) 1. Unfamiliarity with task / First time
2. High workload (large memory) 2. Lack of knowledge (faulty mental model)
3. Simultaneous, multiple actions 3. New techniques not used before
4. Repetitive actions / Monotony 4. Imprecise communication habits
5. Irreversible actionsα 5. Lack of proficiency / Inexperience
6. Interpretation requirements 6. Indistinct problem-solving skills
7. Unclear goals, roles, or responsibilities 7. Unsafe attitudes
8. Lack of or unclear standards 8. Illness or fatigue; general poor health or injury
Work Environment Human Nature
1. Distractions / Interruptions 1. Stress
2. Changes / Departure from routine 2. Habit patterns
3. Confusing displays or controls 3. Assumptions
4. Work-arounds / OOSβ instrumentation 4. Complacency / Overconfidence
5. Hidden system / equipment response 5. Mind-set (intentions)
6. Unexpected equipment conditions 6. Inaccurate risk perception
7. Lack of alternative indication 7. Mental shortcuts or biases
8. Personality conflict 8. Limited short-term memory
αIrreversible actions are not necessarily precursors to error, but are often overlooked, leading to
preventable events. It is included in this list because of its importance.
βOOS - out of service
Section 53
Remember, by themselves, error precursors do not define an error-likely situation. A human act
or task must be either planned or occurring concurrent with error precursors to be considered
error-likely. Several examples are provided below. For each example, notice the underlined
action. Recall that an error is an unintended action.
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Department of Energy Human Performance Handbook Chapter 2 Reducing Error
1. Writing the wrong year on personal checks at the beginning of a new year.
Error
Precursors:
• Change – new year
• Repetitive action – write several checks
• Habit pattern – written previous year numerous times during the
previous year
2. Turning the charging pump switch instead of the dilution valve switch.
Error
Precursors:
• Confusing displays and controls – identical switches – both pistol-
grip style
• Adjacent – within an inch apart – both pistol-grip controls very close
together
• Interruption – verifying the status of several annunciator alarms just
at the moment to start dilution
• Repetitive action – done several times during shift while performing
system startup
3. Pouring engine oil (the wrong product) into a hydraulic fluid system.
Error
Precursors:
• Time pressure – behind schedule getting equipment on line
• Departure from routine – poor lighting in store room where products
were stored
• Complacency, mind-set – location of fluids on unmarked shelves
next to each other
• Assumptions – containers appear nearly identical
Many different factors can affect performance. Considering the number and variety of factors
involved with a specific job, many things can change, even with simple, repetitive tasks.
Consequently, no work should be considered routine. When people believe a job is routine, they
subconsciously think that “nothing can go wrong,” and they expect only success. This mind-set
leads to complacency and overconfidence. Then, when something does go wrong, people tend to
rationalize the situation away, inhibiting proper response in time to avert the consequences.95
Most events originate during routine activities. A sub-principle of human performance is there
are no routine tasks.
ERROR-PREVENTION TOOLS
There are two ways to prevent human error from disturbing the facility or harming other
important assets: either keep people from making errors (error prevention) or prevent the errors
from harming the facility’s (controls). The design of systems, structures, and components aids
in performing the latter through engineered controls such as physical barriers, interlocks, keyed
parts, shaped/color-coded controls, automation, and alarms. However, the prevention of or
detection of errors also depends on people, either the performer or other people. For example,
self-checking and procedures provide individuals with the means of avoiding or detecting
mistakes, while peer-checking and three-way communication engage another person. Human
performance tools are designed to help people anticipate, prevent, and catch active errors.
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Methods of controlling latent errors are designed more to catch them than to prevent them
because, by definition, people are usually unaware when latent errors occur.
Section 54
Human Performance Improvement Handbook Volume 2: Human Performance Tools For
Individuals, Work Teams, and Management, is a companion publication to this handbook.
Volume 2 provides an explanation of numerous tools that individuals and work teams can
employ to reduce errors. The fundamental purpose of human performance tools is to help the
worker maintain positive control of a work situation; that is, what is intended to happen is what
happens, and that is all that happens. Every person wants to do good work, to be 100 percent
accurate, 100 percent complete, and meet 100 percent of the requirements. However, error is a
normal characteristic of being human. Regardless of one’s intention to do a job well, errors still
occur because of the inherent fallibility and variability of all human beings. On occasion, people
still err despite how rigorously they use human performance tools. For this reason, we take the
dual approach to manage controls as well as reducing error (Re + Mc = ØE).
System Changes
Although this handbook focuses on what people can do to reduce human error, it is recognized
there is another whole dimension associated with error reduction. This involves improvements
or changes in the engineered systems so the machines and working conditions better support the
human needs, thus reducing human error. The location of instruments and controls on operating
control panels, the accessibility and positioning of monitoring equipment, the lighting in
passage ways, the sounds of warning alarms, the heights of working surfaces, the distance from
communication sources, the number of work a-rounds present, and numerous other conditions
can either enhance or hinder human performance. Human error is more likely when tools and
equipment, procedures, work processes, or technical support are inadequate. Human factors
professionals study and report on adverse engineered and management systems within an
organization and recommend modifications or improvements to eliminate these and other
conditions. Implementation of such recommendations improves worker perform and reduces
human error.
Reporting errors and error precursors is an essential behavior needed to acquire feedback from
the field about flawed engineered or management systems. Managers and supervisors should
encourage workers to report adverse system-related conditions that promote error (error
precursors) when ever they are encountered. With input from worker reporting, management
can direct needed engineering and system changes. Reporting should be carried out in
accordance with the organization’s reporting policies, procedures and practices. More will be
said about how to encourage a reporting culture in Chapter of this handbook.
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ATTACHMENT A – ERROR PRECURSORS
The conditions listed below were derived from an in-depth study of INPO’s event database and
several highly regarded technical references on the topic of error. Many references refer to error
precursors as behavior-shaping factors or performance-shaping factors. The bolded error
precursors are more prevalent and are listed in order of impact.96 Other error precursors are not
listed in any particular order.
Task Demands Individual Capabilities
• Time pressure (in a hurry)
• High workload (memory
requirements)
• Simultaneous, multiple tasks
• Repetitive actions / Monotony
• Irreversible actsα
Section 55
• Interpretation of requirements
• Unclear goals, roles, or
responsibilities
• Lack of or unclear standards
• Confusing procedure / Vague
guidance
• Excessive communication
requirements
• Delays; idle time
• Complexity / High information flow
• Long-term monitoring
• Excessive time on task
• Unfamiliarity with task / First time
• Lack of knowledge (faulty mental
model)
• New technique not used before
• Imprecise communication habits
• Lack of proficiency / Inexperience
• Indistinct problem-solving skills
• ‘Unsafe’ attitudes for critical task
• Illness / Fatigue / injury (general
health)
• Unawareness of critical parameters
• Inappropriate values
• Major life event: medical, financial,
and emotional
• Poor manual dexterity
• Low self-esteem; moody
• Questionable ethics (bends the rules)
• Sense of control / Learned
helplessness
• Personality type
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Work Environment Human Nature
• Distractions / Interruptions
• Changes / Departure from routine
• Confusing displays / Controls
• Work-arounds / OSSβ
instrumentation
• Hidden system response
• Unexpected equipment conditions
• Lack of alternative indication
• Personality conflicts
• Back shift or recent shift change
• Excessive group cohesiveness / peer
pressure
• Production overemphasis
• Adverse physical climate (habitability)
• No accounting of performance.
• Conflicting conventions; stereotypes
• Poor equipment layout; poor access
• Fear of consequences of error
• Mistrust among work groups
• Meaningless rules
• Nuisance alarms
• Unavailable parts or tools
• Acceptability of “cookbooking”
practices
• “Rule book” culture
• Equipment sensitivity (inadvertent
actions)
• Lack of clear strategic vision or goals
• Stress (limits attention)
• Habit patterns
• Assumptions (inaccurate mental
picture)
• Complacency / Overconfidence
• Mind-set
• Inaccurate risk perception
(Pollyanna)
• Mental shortcuts (biases)
• Limited short-term memory
• Pollyanna effect
• Limited perspective (bounded
rationality)
• Avoidance of mental strain
• First day back from vacation / days
off
• Sugar cycle (after a meal)
• Fatigue (sleep deprivation and
biorhythms)
• Tunnel vision (lack of big picture)
• “Something is not right” (gut feeling)
• Pattern-matching bias
• Social deference (excessive
professional courtesy
• Easily bored
• Close-in-time cause-effect
correlation
• Difficulty seeing own errors
• Frequency and similarity biases
• Availability bias
• Imprecise physical actions
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Work Environment Human Nature
• Identical and adjacent displays or • Limited attention span
controls
• Out-of-service warning systems • Spatial disorientation
• Lack of procedure place-keeping • Physical reflex
• • Anxiety (involving uncertainty)
α Irreversible actions are not necessarily precursors to error, but are often overlooked, leading to
preventable events. It is included in this list because of its importance.
β OOS - out of service
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ATTACHMENT B – COMMON ERROR-PRECURSOR DESCRIPTIONS
Section 56
The first eight error precursors from the table on the previous pages are described below. These
tend to be the more commonly encountered conditions that provoke errors. The error precursors
for each category are arranged in order of influence.
Task Demands Description
Time pressure
(in a hurry)
Urgency or excessive pace required to perform action or
task
Manifested by shortcuts, being in a hurry, and an
unwillingness to accept additional work or to help others
No spare time
High workload
(high memory requirements)
Mental demands on individual to maintain high levels of
concentration; for example, scanning, interpreting,
deciding, while requiring recall of excessive amounts of
information (either from training or earlier in the task)
Simultaneous, multiple tasks Performance of two or more activities, either mentally or
physically, that may result in divided attention, mental
overload, or reduced vigilance on one or the other task
Repetitive actions /
Monotony
Inadequate level of mental activity resulting from
performance of repeated actions; boring
Insufficient information exchange at the job site to help
individual reach and maintain an acceptable level of
alertness
Irrecoverable acts Action that, once taken, cannot be recovered without
some significant delay
No obvious means of reversing an action
Interpretation requirements Situations requiring “in-field” diagnosis, potentially
leading to misunderstanding or application of wrong rule
or procedure
Unclear goals, roles, and
responsibilities
Unclear work objectives or expectations
Uncertainty about the duties an individual is responsible
for in a task that involves other individuals
Duties that are incompatible with other individuals
Lack of or unclear standards Ambiguity or misunderstanding about acceptable
behaviors or results; if unspecified, standards default to
those of the front-line worker (good or bad)
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Work Environment Description
Distractions / Interruptions Conditions of either the task or work environment
requiring the individual to stop and restart a task
seq