Human Factors Course
Session 2
2007 March 28
Eric Davey
Crew Systems Solutions
1
Introduction
Session 2 - Understanding human capabilities

Topics
 Dimensions of human capabilities
 Model of cognition
Perception, memory, attention, decision-making
 Personality variation
 Performance influencing factors
 Human error
Characteristics
Treatment strategies
 Participant error experience
 Task analysis
2
Human Performance
Understanding Capabilities & Performance Variability
PERCEPTION
• Sensitivity
• Discrimination
• Recognition
PHYSICAL
• Stature
• Strength
• Endurance
REASONING
• Knowledge
• Experience
• Strategies
PERSONALITY
• Preferences for
- Information sources
- Reasoning strategies
- Learning styles
3
Human Performance
Capabilities and Limitations

A Model of Cognition
Attention
Decision
Making
Perception
Sensory
Store
Action
Execution
Short-term
Memory
Long-term
Memory
Stimuli
Feedback
Response
4
Human Performance
Capabilities and Limitations

Perception
 Function
Feature and change detection
Pattern recognition
 Modalities - Independent
• Auditory
• Visual

Operation
Autonomic - No conscious attention
Representation capture - Quickly overwritten
5
Human Performance
Capabilities and Limitations

Memory
Function
Retention of information & relationships
Capacity
Duration & Recall
 Structures

 Short-term
 Long-term
Limited
Infinite
Short-Rehearsal
Categorization
Modalities
Verbal and Spatial
 Representation

Semantic
(Associative networks)
Episodic
(Time sequence)
6
Human Performance
Capabilities and Limitations

Attention
Function
Enabling resource of conscious reasoning
 Modality independent - Capacity limited
 Types
Selective - Single Task
Divided - Multiple tasks
 Resource demands function of:
Task familiarity
Task complexity

7
Human Performance
Capabilities and Limitations

A Model of Decision-Making
Goals
Interpret
Identify
Observe
Styles
Evaluate
Define
Task
Knowledge-based
Rule-based
Select
Actions
Detect
Execute
Stimuli
Response
Skills-based
8
Human Performance
Capabilities and Limitations

Decision-Making Characteristics
Strong
Knowledge
Attention
&
Effort
Rules
Skills
Minimal
Slow
Performance
Fast
9
Human Performance
Personality Styles

Four Dimensions
 Orientation and Energy
Extroversion - Introversion



E
I
S
N
Decision-Making (Judging) Functions
Thinking - Feeling
T
F
Attitudes of Functions
Judging - Perceiving
P
Perceiving Functions
Sensing - Intuition
J
10
Human Performance
Personality Variations
Sensing
ISTJ
ISFJ
Intuitive
INFJ
INTJ
Introversion
Judging
ISTP
ISFP
INFP
INTP
Perceiving
ESTP
ESFP
ENFP
ENTP
ESTJ
ESFJ
ENFJ
ENTJ
Extraversion
Feeling
Thinking
11
Human Performance
Characteristics of Human Performance

Subject to Influence
Influencing Factors
Cognitive Impact
• Prior Experience
• Interpretation bias
• Loading
• Capacity decrement
• Distraction
• Disruption
• Stress
• Capacity decrement
• Emotion
• Narrows perception
• Fatigue
• Performance decrement
Potential for performance
decrement, variability or error
12
Human Performance
Impact of Stress
Low
Stress
High
Information Intake
Sources
Breadth
Perception of Time
Actual
Perceived
13
Human Performance
Impact of Workload
Performance
Maximum
Reserve
Capacity
Resource
Availability
Low
High
Workload - Resources demanded
14
Human Performance
Decision-Making Example

Juggling
Strong
Knowledge
Attention
&
Effort
Real-time spatial
calculations
Rules
Repeat
IF Ball N at top
THEN Throw ball N+1
Visual perception and
proprieoceptive feedback
Skills
Minimal
Slow
Performance
Fast
15
Human Error
Aviation Experience

Earl Wiener

Every device creates its own opportunity for human error

Exotic devices create exotic problems

Human error is the price we pay for flexibility

Necessity is the mother of improvisation

In GOD we trust:
Everything else must be monitored
16
Human Error
What is Human Error?

Definition

A failure of a human to behave as required Opportunity for learning
Type
Cognitive Stage
Mistake
Perception
Decision-making
Slip
Action
Causes
• Misinterpretation
• Bias
• Distraction
• Inattention
• Predisposition
• Poor differentiation
17
Human Error
Nature of Human Error

Occurrence

Situation dependent
Type
Cognitive Style
Frequency
Error %
Mistake
Knowledge
1 in 3/10
15 %
Rule
1 in 100/1000
60 %
Skill
1 in 1000/5000
25 %
Slip

Error Correcting Behaviour

~85% of errors are self-detected & recovered
18
Human Error
Nature of Human Error


Time of Day Distribution
Time
Frequency
Days
51 %
Evenings
21 %
Nights
28 %
Average Errors Per Person
Category
Days
Evenings
Nights
Operations
0.23
0.16
0.23
Maintenance
0.04
0.16
0.41
19
Human Error
Nature of Technical Failures

Universal Learning Curve
IF learning occurs,
THEN failure rate declines with
accumulated experience
Failure Rate
Minimum failure rate is
• Finite and non-zero
• Due to human error
Experience
20
Human Error
How Challenges Occur
Ongoing
Generation
Of
Situations
Breakdowns
• Latent
• Immediate
An Event
Human Error
21
Human Error
Causal Factors

Breakdowns in Support
Human Error
&
Undesired
Performance
• Workspace
20 %
• Change
Process
5%
Person
• Training
13 %
• Fatigue
4%
• Communication
16 %
• Supervision
Operational
12 %
Environment
• Procedures
22 %
Desired
Performance
Physical
Design
22
Human Error
A Strategy To Minimize Error Impact

Promote a learning environment



Report and track challenges
Assess impacts
Change task characteristics


Reduce Error Occurrence
 Elimination - Task restructuring
 Reduction - Coding & Affordances
Reduce Adverse Impact of Occurrence
 Prevention - Action reversibility, Interlocks
 Mitigation - Margins, Response resources
23
Human Error
An Alternative Human Error Strategy

Reality


Premise


Half of all errors are Skill-based
Skill-based behaviour at greatest risk of error
Situational Factors
Experienced with task
 Performed by habit - Minimal attention
 Risk outweighs danger due to task familiarity

Vulnerability
To Error
24
Human Error
An Alternative Human Error Strategy

Recommended Action
Right
Instill awareness of error vulnerability
Conduct all tasks with conscious attention
Think Danger, Not Safety
 Wrong
Human nature to make errors

We have a conscious choice to make!
Al Pedersen
Corporate Effects
25
Human Error
Selecting Error Defences

A Universal Defence?
CAUTION
THIS MACHINE HAS
NO BRAIN
USE YOUR OWN
26
Human Error
Selecting Error Defenses
Defensive
Feature
Cognitive Stage Applicability
Perception
Decisions
Action
Labeling
Visual coding
Affordances
Interlocks
Warnings
Procedures
Self-check
Verification
Undo
27
Exercise
Experiences with Human Error

Instances
What happened
 Context
 Type - Mistake or Slip
 Influencing factors
Environment
Task requirements
User capabilities
 Treatment

28
Human Performance
Operational Challenges

Conversion Gulfs
Execution
Evaluation
Process State
Activities
State
Gulf
Gulf
Actions
Data
Gulf
Gulf
Intentions
Information
Goals
29
Human Performance
Supporting Human Performance

Supportive Task Environment
Complete information
 Reduce memory dependence
 Simplified actions/tasks
 Visibility
Intentions & actions
Feedback
 Standardize
 Reduce distractions
 Accommodate performance variability & error

30
Task Analysis
Definitions

Function


The capability that a person, system or structure provides to
fulfill a goal.
Task

A set of actions performed by a person over time to achieve
an operational goal -- (activity sequence).
31
Task Analysis
Task Analysis

Purpose


To characterize and assess human
activities to support system operation
Stages
Identification
Establish objectives and scope
 Description
Characterize task properties
 Assessment
Evaluate acceptability

32
Task Analysis
Identification

Objectives & Scope
Goals
Functions
Agents
Actions
People
Tasks
• Configuration
• Supervision
• Intervention
• Servicing
Working
Together
Well
Systems
Automation
• Control
• Monitoring
• Detection
• Respond to user
33
Task Analysis
Description

Task Properties
Identification
Name
Purpose
Strategies
 Activities (Organization - hierarchy & sequence)
Actions - Objects - States - Feedback
Decisions - Information - Criteria - Output
Communications - Information - Who/What

34
Task Analysis
Description (continued)

Task Properties
Prerequisites
System states
Other tasks
Information
Resources
 Triggers
Initiating conditions
Continuing conditions
Terminating conditions

35
Task Analysis
Description

Task Properties

Performance requirements
Achievements
Accuracy
Duration
Co-ordination
Compliance criteria
36
Task Analysis
Assessment

Criteria
Performance
Support for operational goals
Workload
Error mechanisms. risk of occurrence, and consequence
 Human capabilities
Margins to limits - Refer to guidance
 Regulatory standards
Compliance

37
Task Analysis
Why do Task Analysis?

Design inputs
Definition of human role - training
 Definition of controls & displays in system interfaces
 Definition of operational/maintenance procedures


System assessment
Demonstration human role can be fulfilled
 Basis (plan) for system operational validation

38