human factors lecture 3pp
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INTRODUCTION TO HUMAN FACTORS
Dr Nathan Perry n.perry@uws.edu.au
101183 Behavioural Science
What is Human Factors?
Understand human interactions with a system Factors that influence human performance
What is Human Factors?Human Characteristics
Task Characteristics Environment
Attention capacity Workload Illumination
Working memory capacity
Level of training Noise
Expertise Display design Vibration
Communication skills OrganisationalCulture
Climate
Personality Technological reliability
Altitude
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Human ErrorShooter A Shooter B
Variable Error Constant Error
Reason (1990)
Information Processing
Information Processing
Wickens & Carswell (2006)
Information Processing Errors
Slips Not Deliberate Failure of attention
Lapses Not Deliberate Failure of memory
Mistakes Deliberate Wrong course of action
Reason (1990)
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PerceptionQuestion
You are designing a new phone book. Which of the following formats would you choose?
(a) Nathan Perry n.perry@uws.edu.au 97726139
(b) Nathan Perry n.perry@uws.edu.au 97726139
Cognitive Factors
PerceptionDefinition: Extraction of meaning from information
Processes
1. Bottom-up processing
2. Top-down processing
Cognitive Factors
PerceptionBottom-up processing
Analysis and integration of features
Characteristics Slow
Effortful
Does not require experience
Cognitive Factors
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PerceptionTop-down processing
Perception shaped by previous experience
Recognition of the whole
Characteristics Fast
Relatively automatic
Requires previous experience
Cognitive Factors
Perception: Human Factors Implications
Feature degradation reduces ability for bottom-up perception
Top-down processing still possible with degraded features
Cognitive Factors
Perception: Human Factors Implications
Display of information In context: words perceived top-down
Random numbers: perceived bottom-up
If display provides both text and numbers display numbers in larger font to aid bottom-up
Wickens et al. (2004)
Cognitive Factors
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PerceptionQuestion
You are designing a new phone book. Which of the following formats would you choose?
(a) Nathan Perry n.perry@uws.edu.au 97726139
(b) Nathan Perry n.perry@uws.edu.au 97726139
Wickens et al. (2004)
Cognitive Factors
Perception
Cognitive Factors
Cognitive Factors
Perception
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Cognitive Factors
Perception
Cognitive Factors
Memory
Working Memory: Short-term memory store which enables the manipulation of information
Long-Term Memory: prolonged storage of information for later retrieval
Cognitive Factors
Memory: Human Factors Implications
Working Memory: Processing requirements exceed working memory capacity performance decline
Long-term memory: Inability to retrieve information
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Cognitive Factors
Working Memory
Rail Control Example
Cognitive FactorsDecision-MakingDefinition: Choice between alternative options or courses of action
Theorised to involve:(a) Information acquisition(b) Information interpretation(c) Planning and selecting choices
Cognitive Factors
Decision-Making
Use a range of different decision strategies
Simple Complex
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Cognitive Factors
Decision-Making
Situation Simple or Complex
Requires Accuracy Complex
Little Time Available Simple
Vast amount of information
Simple
Little Task Experience Complex
Cognitive FactorsDecision-Making: Expertise Interviews with expert Fire Ground Commanders
Don’t compare and contrast decision options Recognise the situation
Use cues present in the environment to recall similar situations from memory
Use strategy taken in previous situation
Klein (1989)
Cognitive Factors
Decision-Making: Human Factors Implications
Tendency to limit info. analysis Effortful & time-consuming
Reduced potential for accuracy
Implement systems to reduce effort associated with info. analysis
Perry et al. (2012)
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Cognitive Factors
Decision-Making: Human Factors Implications
Display critical information
Advises on a course of action
Determines and executes course of action
Traffic Collision Avoidance System (TCAS)
Climb! Climb! Descend! Descend!
Cognitive Factors
Attention Information processes require attention
Limited attention capacity Cannot attend to everything
Without attention information unlikely to be processed
Cognitive Factors
Attention: Human Factors ImplicationsAttention required for info processing
Ensure that operators attend to crucial information
Design systems to ensure attention is given to crucial information
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Design
Lever underneath seat in van
Q: What will happen if
the lever is pulled?
A: Seat detaches from floor
Design
A: Mop sink
Design
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Design
System Design Airbus A320 accident in Strasbourg 1992
Pilot engaged behaviour that was inappropriate for current mode
Appropriate for different mode
Preparing to land – autopilot Needed change flight angle to 3.3 degrees
Flight management system set in the vertical speed mode Pilot dialled 3.3 into flight control unit In this mode this meant a speed of 3300 feet per minute! Instead of 800 feet per minute
Overreliance on Automation
Role of human operator with automated system is often to monitor
Humans have a tendency to put a lot of trust in automated systems
Out-of-the-loop performance problem Automation Induced Complacency Automation Bias Skill Loss
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Automation-Induced ComplacencySystem Monitoring Tracking
Fuel Management
Parasuraman et al. (1993)
Task
Computer-based flight simulation
Participants task to detect automation failures
Reliability of automation manipulated
Constant vs. Variable
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0.2
0.4
0.6
0.8
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1 2 3 4 5 6 7 8 9 10 11 12
Constant
Variable
Total Automation Failure
0
Pro
babi
lity
of d
etec
ting
syst
em
ma
lfun
ctio
n
Trial Block
Modified from Parasuraman et al. (1993)
Automation-Induced Complacency
Reliability
Automation-Induced Complacency
Automation: Human Factors Implications
1. Keep the operator informed
2. Keep the operator trained
3. Keep the operator in the loop
4. Select appropriate levels of automation
Wickens et al. (2004)
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Accident Causation
Reason (2000)
Summary Human factors issues are complex
Role of human factors specialist Facilitate the fit between humans and the system
Role of psychologist Consider the psychological issues to ensure fit between
humans and system
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