The Origins of the SPAR-H Method’s Performance Shaping Factor Multipliers

Ronald L. Boring & Harold S. Blackman

Idaho National Laboratory

SPAR-H was built on the premise that a model of human behavior underpinning the method would provide a basis to direct further development• Ensure all relevant factors are addressed/accounted

for• Appropriate for all human behavior• Allow developers to work forward from accepted,

underlying mechanisms that have a basis in psychology

A total of five steps were executed to develop the model• Define a model of human behavior• Describe the details of the model in behavioral

terms• Complete the description in terms of factors of plant

operation to characterize the behavior• Refine total list to summary level factors (PSFs)• Develop a quantification scheme

Model Assumptions

• Model is based on human performance and cognition not on a specific plant condition

• A general human behavior model sufficiently describes human performance for human reliability analysis

• PSFs can be identified that influence decision making and actions and cover each stage of the human behavior

• Plant conditions, tasks, people, and situations combine to create a context described by PSFs that influence performance

Method attributes

• Two task types, diagnosis and action (originally processing and response), are sufficient to describe performance at a task or subtask level– Distinct failure rates are associated with each

• Context is described by Negative PSFs that degrade performance and positive PSF that improve performance– Rates are benchmarked

• Dependency is definable as a combination of cues, location, time, and crew

Inflow and Perception Working Memory/Short Term memory

Processing and Long-term Memory

Response

Presence6,3 (is signal there?) and opportunity (is anyone present to receive the signal?)

Human sensory limits2,5,7

Modality6,5,4,7 (verbal, graphic/symbol, text)

EchoicIconicKinesthetic

Interference6,5,4,7

Limited capacity5

Serial processingShort time

Right amount of attention required2,3,4,5,7

Rehearsal2,3,5,7

Physical and Mental Health7

Training4 (models, problem solving, behaviors)

Experience4 (models, problem solving, behaviors)

Culture8 (societal, organizational, interpersonal, (crew))

Intelligence/cognitive skills3,4,1,5,7 (decision making, problem solving)

Interference factors6,2,3,7

(distrction)

Available time1,3

Physical and mental Health7

Training4 (actions)Existing models of

behaviorPractice and skill

Experience4 (actions)Existing models of

behaviorPractice and skill

Proper controls available6

Human action limits6,7

physical strength, and sensory acuity

Ergonomics of controls6,3

Complexity

Environmental degradation2,3,6

Time to react versus time available1

Performance Shaping Factors:Available time1, Stress and stressors2, Complexity3, Experience and training4, Procedures (including job aids)5,

Ergonomics and human-machine interface6, Fitness for duty7, Work processes8

Originally, Modification factors and nominal error rates were taken from THERP• THERP was selected because:• At the time, recent studies suggest that TERP has a

reasonable level of validity (Zimolong, 1992)• THERP had a readily available values to work with

and is a technique familiar to the industry

Origins of the nominal HEPS

• Processing/Diagnosis: Nominal HEP = 1E-2

• Nominal HEP for processing/diagnosis is based upon THERP Table 20-1 item 4

• Median HEP for a control room diagnosis in 30 minutes

• Follows 30 minute rule for control room action

Origins of the Nominal HEPS

• Response/Action: Nominal HEP = 1E-3

• WASH-1400, appendix III, Table III 6-1 erroneous activation of a switch

• THERP– Incorrectly following a

written procedure– Incorrectly selecting an

unannunciated display– Incorrectly check

reading digital or analog indicators/meters

– Incorrectly selecting/activating a locally operated valve

Origins of PSFs

• PSFs based upon:– Description of cognitive model– Identification of psychological factors know to

affect each step in the cognitive model– Parsed into 6 PSFs deemed to have the most

relevance and impact on human performance based upon detection, perception, decision making, and action

ASP HRA/SPAR-H (1995) THERP

PSF PSF Category

PSF Level

Processing HEP1

ResponseHEP1

HEP for Process

ing2

HEP for Response2

Inadequate Time

1.0 (∞) 1.0 (∞) 1.0 (20-1, 1)

Adequate Time

0.05 (5) 0.005 (5) 0.005 (20-23, 6)

Expansive Time

0.02 (2) 0.002 (2) 0.002 (20-23, 4)

Inadequate Time

1.0 (∞) 1.0 (∞) 1,0 (20-1, 1)

Adequate Time

0.01 (1) 0.001 (1) 0.01 (20-1, 4)

Expansive Time

0.01 (1) 0.001 (1) 0.001 (20-1, 5)

Poor Training

0.1 (10) 0.01 (10) 10x (20-16, 5)3

Good Training

0.01 (1) 0.001 (1) 1x (20-16, 2)3

Poor Training

0.05 (5) 0.005 (5) 5x (20-16, 5)3

Good Training

0.005 (0.5

)

0.0005 (0.5)

0.5x (20-16)4

High Experien

ce

Low Experien

ce

Experience/ Training

Low Threat and Stress

High Threat and Stress

Complexity, Stress, and Workload

ASP HRA/SPAR-H (1995) THERP

PSF PSF Category

PSF Level Processing HEP1 Response

HEP1 HEP for Processing2 HEP for Response2

Procedures Absent N/A 0.1 (10) 0.01 (10) 2x (20-22, 2)5

Poor Procedures 0.05 (5) 0.005 (5) 0.05 (20-7, 5) 0.005 (20-6, 9)

Good Procedures 0.01 (1) 0.001 (1) 0.001 (20-7, 1)

Poor Ergonomics 0.05 (5) 0.005 (5) 0.005 (20-12, 12)

Good Ergonomic

s

0.01 (1) 0.001 (1) 0.001 (20-12, 3)

Poor Ergonomics 0.03 (3) 0.003 (3) 0.003 (20-12, 2)

Good Ergonomic

s

0.007 (0.7) 0.0007 (0.7) 0.0005 (20-12, 5)

Poor Ergonomics 0.02 (2) 0.002 (2) 0.003 (20-9, 4)

Good Ergonomic

s

0.004 (0.4) 0.0004 (0.4) 0.0005 (20-9, 1)

New Plant

Retrofit Plant

Old PlantErgonomics

Procedures Present

Procedures

ASP HRA/SPAR-H (1995) THERP

PSF PSF Category

PSF Level

Processing HEP1

ResponseHEP1

HEP for Processing2

HEP for Response2

Unfit N/A 0.25 (25) 0.025 (25)

Fit N/A 0.01 (1) 0.001 (1)

Poor Crew Dynamics

N/A 0.1 (10) 0.01 (10)

Good CrewDynamics

N/A 0.01 (1) 0.001 (1)

Crew Dynamics

Fitness for Duty

2005 SPAR-H 1995 ASP HRA PSF Multiplier(SPAR-H | ASP HRA)

PSF PSF Level PSF PSF Category PSF Level Processing/ Diagnosis Response/ Action

Inadequate time Complexity, Stress, Workload

Low Threat and Stress

Inadequate Time

∞ | ∞(See Note 1)

∞ | ∞(See Note 1)

Barely adequate time

10 | ∅(See Note 2)

10 | ∅(See Note 2)

Nominal time Complexity, Stress, Workload

Low Threat and Stress

Adequate Time 1 | 1 1 | 1

Extra time 0.1 | ∅(See Note 2)

0.1 | ∅(See Note 2)

Expansive time Complexity, Stress, Workload

Low Threat and Stress

Expansive Time

0.01 | 1(See Note 3)

0.01 | 1

Extreme Complexity, Stress, Workload

High Threat and Stress

Adequate Time 5 | 5 5 | 5

High Complexity, Stress, Workload

High Threat and Stress

Expansive Time

2 | 2 2 | 2

Nominal Complexity, Stress, Workload

Low Threat and Stress

Adequate Time 1 | 1 1 | 1

Stress/ Stressor

s

Available Time

2005 SPAR-H 1995 ASP HRA PSF Multiplier(SPAR-H | ASP HRA)

PSF PSF Level PSF PSF Category PSF LevelProcessing/

Diagnosis

Response/ Action

Highly complex Complexity, Stress, Workload

High Threat and Stress

Adequate Time

5 | 5 5 | 5

Moderately complex

Complexity, Stress, Workload

High Threat and Stress

Expansive Time

2 | 2 2 | 2

Nominal Complexity, Stress, Workload

Low Threat and Stress

Adequate Time

1 | 1 1 | 1

Obvious diagnosis

0.1 | ∅(See Note

2)

Low Experience/ Training Low Experience Poor Trainin

g

10 | 10 3 | 10

Nominal Experience/ Training Low Experience Good Trainin

g

1 | 1 1 | 1

High Experience/ Training High Experience Good Trainin

g

0.5 | 0.5 0.5 | 0.5

Experience/

Training

Complexity

2005 SPAR-H 1995 ASP HRA PSF Multiplier(SPAR-H | ASP HRA)

PSF PSF Level PSF PSF Category PSF LevelProcessing/

Diagnosis

Response/ Action

Not available Procedures Procedures Absent N/A 50 | 10 50 | 10

Incomplete 20 | ∅(See Note 2)

20 | ∅(See Note 2)

Available, but poor Procedures Procedures Present Poor Procedures 5 | 5 5 | 5

Nominal Procedures Procedures Present Good Procedures 1 | 1 1 | 1

Diagnostic/symptom oriented 0.5 | ∅(See Note 2)

Missing/Misleading 50 | ∅(See Note 2)

50 | ∅(See Note 2)

Poor Ergonomics Old Plant Poor Ergonomics 10 | 5 10 | 5

Nominal Ergonomics Old Plant Good Ergonomics 1 | 1 1 | 1

Good Ergonomics New Plant Good Ergonomics 0.5 | 0.4 0.5 | 0.4

Ergonomics/ HMI

Procedures

2005 SPAR-H 1995 ASP HRA PSF Multiplier(SPAR-H | ASP HRA)

PSF PSF Level PSF PSF Category

PSF Level

Processing/ Diagnosi

sResponse/

Action

Unfit Fitness for Duty Unfit N/A ∞ | 25 ∞ | 25Degraded Fitness 5 | ∅

(See Note 2)5 | ∅

(See Note 2)Nominal Fitness for Duty Fit N/A 1 | 1 1 | 1Poor Crew Dynamics Poor Crew Dynamics N/A 2 | 10 5 | 10Nominal Crew Dynamics Good Crew Dynamics N/A 1 | 1 1 | 1Good 0.8 | ∅

(See Note 2)0.5 | ∅

(See Note 2)

Work Processes

Fitness for Duty

SPAR-H (NUREG/CR-6883) THERP (NUREG/CR-1278)

PSFs PSF Levels HEP for Diagnosis1

HEP for Action1

HEP for Diagnosis2

HEP for Action2

Inadequate time 1.0 (no multiplier)

1.0 (no multiplier) 1 (20-1, 1)

Barely adequate time 0.1 (10) 0.01 (10) 0.1 (20-1, 3)

Nominal time 0.01 (1) 0.001 (1) 0.01 (20-1, 4)

Extra time 0.001 (0.1) 0.0001 (0.1) 0.001 (20-1, 5)

Expansive time 0.0001 (0.1-0.01) 0.00001 (0.01) 0.0001 (20-1, 6)

Extreme 0.05 (5) 0.005 (5) 0.25 5x (20-16, 6)3

High 0.02 (2) 0.002 (2) 2x (20-16, 4)3 2x (20-16, 4)3

Nominal 0.01 (1) 0.001 (1) 1x (20-16, 2 or 3)3 1x (20-16, 2 or 3)3

Stress/ Stressors

Available Time

SPAR-H (NUREG/CR-6883) THERP (NUREG/CR-1278)

PSFs PSF Levels HEP for Diagnosis1

HEP for Action1

HEP for Diagnosis2

HEP for Action2

Highly complex 0.05 (5) 0.005 (5) 0.005 (20-23, 6)

Moderately complex 0.02 (2) 0.002 (2) 0.002 (20-23, 4)

Nominal 0.01 (1) 0.001 (1) 0.001 (20-23, 3)

Obvious diagnosis 0.001 (0.1) N/A 0.0001 (20-23, 1)

Low 0.1 (10) 0.003 (3) 2x (20-16, 7)3 2x (20-16, 4 or 5)3

Nominal 0.01 (1) 0.001 (1)

High 0.05 (0.5) 0.0005 (0.5)

Not available 0.5 (50) 0.05 (50) 0.05 (20-7, 5)

Incomplete 0.2 (20) 0.02 (20) 0.01 (20-7, 3)

Available, but poor 0.05 (5) 0.005 (5) 0.003 (20-7, 2)

Nominal 0.01 (1) 0.001 (1) 0.001 (20-7, 1)

Diagnostic/symptom oriented

0.005 (0.5) N/A

Procedures

Experience/

Training

Complexity

SPAR-H (NUREG/CR-6883) THERP (NUREG/CR-1278)

PSFs PSF Levels HEP for Diagnosis1

HEP for Action1

HEP for Diagnosis2

HEP for Action2

Missing/Misleading 0.5 (50) 0.05 (50) 0.05 (20-12, 6)

Poor 0.1 (10) 0.01 (10) 0.01 (20-13, 5)

Nominal 0.01 (1) 0.001 (1) 0.001 (20-13, 1)

Good 0.005 (0.5) 0.0005 (0.5)

Unfit 1.0 (no multiplier)

1.0 (no multiplier)

Degraded Fitness 0.05 (5) 0.005 (5)

Nominal 0.01 (1) 0.001 (1)

Poor 0.02 (2) 0.005 (5)

Nominal 0.01 (1) 0.001 (1)

Good 0.008 (0.8) 0.0005 (0.5)

Work Processe

s

Fitness for Duty

Ergonomics/ HMI

General Conclusions

• SPAR-H gives analysts flexibility and generalizability beyond specific tasks

• PSF multipliers are mapped to primary data sources• All HEPs should be evaluated for reasonableness

regardless of source