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Human Factors Course

Session 2

Eric DaveyCrew Systems Solutions

2007 March 28

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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

Introduction

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Understanding Capabilities & Performance Variability

Human Performance

PHYSICAL• Stature• Strength• Endurance

PERCEPTION• Sensitivity• Discrimination• Recognition

REASONING• Knowledge• Experience• Strategies

PERSONALITY• Preferences for - Information sources - Reasoning strategies - Learning styles

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Capabilities and Limitations

A Model of Cognition

Human Performance

Stimuli

DecisionMaking

Short-termMemory

Long-termMemory

SensoryStore

Perception

Attention

ActionExecution

ResponseFeedback

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Capabilities and Limitations Perception

Function Feature and change detection Pattern recognition

Modalities - Independent• Auditory

Operation Autonomic - No conscious attention Representation capture - Quickly overwritten

Human Performance

• Visual

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Capabilities and Limitations

Memory Function

Retention of information & relationships Structures

Short-term Long-term

Modalities Verbal and Spatial

Representation

Human Performance

Semantic(Associative networks)

Episodic(Time sequence)

Capacity Duration & Recall

Limited

Infinite

Short-Rehearsal

Categorization

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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

Human Performance

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Capabilities and Limitations

A Model of Decision-Making

Human Performance

SelectActions

DefineTask

Execute

Evaluate

Observe

Detect

Identify

Interpret

Stimuli Response

Goals

Knowledge-based

Rule-based

Skills-based

Styles

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Capabilities and Limitations

Decision-Making Characteristics

Human Performance

Attention&

Effort

Strong

Minimal

Slow FastPerformance

Knowledge

Rules

Skills

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Personality Styles Four Dimensions

Orientation and Energy Extroversion - Introversion

Perceiving Functions Sensing - Intuition

Decision-Making (Judging) Functions Thinking - Feeling

Attitudes of Functions Judging - Perceiving

Human Performance

I

J

T

S

E

P

F

N

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Personality Variations

Human Performance

Introversion

Extraversion

Sensing Intuitive

Feeling

Thinking

ISTJ

Perceiving

Judging

ISTP

ESTP

ESTJ

ISFJ

ISFP

ESFP

ESFJ

INFJ

INFP

ENFP

ENFJ

INTJ

INTP

ENTP

ENTJ

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Characteristics of Human Performance

Subject to Influence

Human Performance

Influencing Factors Cognitive Impact

• Interpretation bias

• Capacity decrement

• Disruption

• Capacity decrement

• Narrows perception

• Performance decrement

• Prior Experience

• Loading

• Distraction

• Stress

• Emotion

• Fatigue

Potential for performance decrement, variability or error

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Impact of Stress

Human Performance

StressLow High

Information Intake

Perception of Time

Actual

Perceived

Sources

Breadth

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Impact of Workload

Human PerformanceHuman Performance

Performance

Workload - Resources demandedLow High

ResourceAvailability

Maximum

ReserveCapacity

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Decision-Making Example

Juggling

Human Performance

Attention&

Effort

Strong

Minimal

Slow FastPerformance

Real-time spatial calculations

Repeat IF Ball N at top THEN Throw ball N+1

Visual perception andproprieoceptive feedback

Skills

Knowledge

Rules

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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

Human Error

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What is Human Error? Definition

A failure of a human to behave as required - Opportunity for learning

Human Error

Mistake

Slip

Type

PerceptionDecision-making

Cognitive Stage

• Inattention• Predisposition• Poor differentiation

• Misinterpretation• Bias• Distraction

Causes

Action

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Nature of Human Error

Occurrence Situation dependent

Error Correcting Behaviour ~85% of errors are self-detected & recovered

Human Error

Mistake

Slip

Type Cognitive Style Error %Frequency

Knowledge

Rule

1 in 1000/5000

1 in 100/1000

1 in 3/10

Skill

15 %

60 %

25 %

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Nature of Human Error

Human Error

Time of Day Distribution

Average Errors Per Person

Days

Nights

Time Frequency

51 %

21 %

28 %

Evenings

Operations

Category

0.160.23

0.04Maintenance

Days Evenings Nights

0.23

0.16 0.41

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Nature of Technical Failures

Human Error

Universal Learning Curve

Experience

Failure RateMinimum failure rate is • Finite and non-zero• Due to human error

IF learning occurs,THEN failure rate declines with accumulated experience

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How Challenges Occur

Human Error

Pract

ices

An Event

OngoingGeneration

Of Situations

Breakdowns• Latent• Immediate

Human Error

Proce

dure

s

Mai

nten

ance

Des

ign

Fore

sigh

t

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Causal Factors

Breakdowns in Support

PhysicalDesign

OperationalEnvironment

Person

DesiredPerformance

• Communication 16 % • Supervision 12 % • Procedures 22 %

• Training 13 %• Fatigue 4 %

• Workspace 20 %• Change Process 5 %

Human Error

Human Error&

Undesired

Performance

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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

Human Error

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An Alternative Human Error Strategy

Reality Half of all errors are Skill-based

Premise 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

VulnerabilityTo Error

Human Error

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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 PedersenCorporate Effects

Human Error

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Selecting Error Defences

CAUTIONTHIS MACHINE HAS

NO BRAIN

USE YOUR OWN

Human Error

A Universal Defence?

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Selecting Error Defenses

Labeling

Visual coding

DefensiveFeature Perception

Cognitive Stage Applicability

ActionDecisions

Warnings

Procedures

Self-check

Verification

Interlocks

Affordances

Undo

Human Error

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Experiences with Human Error

Instances What happened Context Type - Mistake or Slip Influencing factors

Environment Task requirements User capabilities

Treatment

Exercise

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Operational Challenges

Human Performance

Gulf

Execution

Goals

Conversion Gulfs

Process StateEvaluation

Activities

Intentions

State

Information

Actions Data

Gulf

Gulf Gulf

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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

Human Performance

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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).

Task Analysis

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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

Task Analysis

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Identification

Objectives & Scope

Task Analysis

Agents

Actions

Goals

Functions

WorkingTogether

Well

People Systems

Automation• Control• Monitoring• Detection• Respond to user

Tasks• Configuration• Supervision• Intervention• Servicing

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Description

Task Properties Identification

Name Purpose Strategies

Activities (Organization - hierarchy & sequence) Actions - Objects - States - Feedback Decisions - Information - Criteria - Output Communications - Information - Who/What

Task Analysis

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Description (continued)

Task Properties Prerequisites

System states Other tasks Information Resources

Triggers Initiating conditions Continuing conditions Terminating conditions

Task Analysis

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Description

Task Properties Performance requirements

Achievements Accuracy Duration Co-ordination Compliance criteria

Task Analysis

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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

Task Analysis

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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

Task Analysis