1 Human Factors Course Session 2 Eric Davey Crew Systems Solutions 2007 March 28

2 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

3 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

4 Capabilities and Limitations A Model of Cognition Human Performance Stimuli Decision Making Short-term Memory Long-term Memory Sensory Store Perception Attention Action Execution Response Feedback

5 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

6 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) CapacityDuration & Recall Limited Infinite Short-Rehearsal Categorization

7 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

8 Capabilities and Limitations A Model of Decision-Making Human Performance Select Actions Define Task Execute Evaluate Observe Detect Identify Interpret StimuliResponse Goals Knowledge-based Rule-based Skills-based Styles

9 Capabilities and Limitations Decision-Making Characteristics Human Performance Attention & Effort Strong Minimal SlowFast Performance Knowledge Rules Skills

10 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

11 Personality Variations Human Performance Introversion Extraversion SensingIntuitive Feeling Thinking ISTJ Perceiving Judging ISTP ESTP ESTJ ISFJ ISFP ESFP ESFJ INFJ INFP ENFP ENFJ INTJ INTP ENTP ENTJ

12 Characteristics of Human Performance Subject to Influence Human Performance Influencing FactorsCognitive 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

13 Impact of Stress Human Performance Stress Low High Information Intake Perception of Time Actual Perceived Sources Breadth

14 Impact of Workload Human Performance Performance Workload - Resources demanded Low High Resource Availability Maximum Reserve Capacity

15 Decision-Making Example Juggling Human Performance Attention & Effort Strong Minimal SlowFast Performance Real-time spatial calculations Repeat IF Ball N at top THEN Throw ball N+1 Visual perception and proprieoceptive feedback Skills Knowledge Rules

16 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

17 What is Human Error? Definition A failure of a human to behave as required - Opportunity for learning Human Error Mistake Slip Type Perception Decision-making Cognitive Stage Inattention Predisposition Poor differentiation Misinterpretation Bias Distraction Causes Action

18 Nature of Human Error Occurrence Situation dependent Error Correcting Behaviour ~85% of errors are self-detected & recovered Human Error Mistake Slip TypeCognitive StyleError %Frequency Knowledge Rule 1 in 1000/ in 100/ in 3/10 Skill 15 % 60 % 25 %

19 Nature of Human Error Human Error Time of Day Distribution Average Errors Per Person Days Nights TimeFrequency 51 % 21 % 28 % Evenings Operations Category Maintenance Days EveningsNights

20 Nature of Technical Failures Human Error Universal Learning Curve Experience Failure Rate Minimum failure rate is Finite and non-zero Due to human error IF learning occurs, THEN failure rate declines with accumulated experience

21 How Challenges Occur Human Error Practices An Event Ongoing Generation Of Situations Breakdowns Latent Immediate Human Error Procedures Maintenance Design Foresight

22 Causal Factors Breakdowns in Support Physical Design Operational Environment Person Desired Performance Communication 16 % Supervision 12 % Procedures 22 % Training 13 % Fatigue 4 % Workspace 20 % Change Process 5 % Human Error & Undesired Performance

23 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

24 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 Vulnerability To Error Human Error

25 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 Human Error

26 Selecting Error Defences CAUTION THIS MACHINE HAS NO BRAIN USE YOUR OWN Human Error A Universal Defence?

27 Selecting Error Defenses Labeling Visual coding Defensive Feature Perception Cognitive Stage Applicability Action Decisions Warnings Procedures Self-check Verification Interlocks Affordances Undo Human Error

28 Experiences with Human Error Instances What happened Context Type - Mistake or Slip Influencing factors  Environment  Task requirements  User capabilities Treatment Exercise

29 Operational Challenges Human Performance Gulf Execution Goals Conversion Gulfs Process State Evaluation Activities Intentions State Information ActionsData Gulf

30 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

31 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

32 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

33 Identification Objectives & Scope Task Analysis Agents Actions Goals Functions Working Together Well PeopleSystems Automation Control Monitoring Detection Respond to user Tasks Configuration Supervision Intervention Servicing

34 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

35 Description (continued) Task Properties Prerequisites  System states  Other tasks  Information  Resources Triggers  Initiating conditions  Continuing conditions  Terminating conditions Task Analysis

36 Description Task Properties Performance requirements  Achievements  Accuracy  Duration  Co-ordination  Compliance criteria Task Analysis

37 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

38 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