1. 1
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 Organisational
Culture
Climate
Personality Technological
reliability
Altitude

2. 2
Human Error
Shooter 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)

3. 3
Perception
Question
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
Perception
Definition: Extraction of meaning from information
Processes
1. Bottom-up processing
2. Top-down processing
Cognitive Factors
Perception
Bottom-up processing
 Analysis and integration of features
 Characteristics
 Slow
 Effortful
 Does not require experience
Cognitive Factors

4. 4
Perception
Top-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

5. 5
Perception
Question
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

6. 6
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

7. 7
Cognitive Factors
Working Memory
Rail Control Example
Cognitive Factors
Decision-Making
Definition: 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

8. 8
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 Factors
Decision-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)

9. 9
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 Implications
 Attention required for info processing
 Ensure that operators attend to crucial
information
 Design systems to ensure attention is given
to crucial information

10. 10
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

11. 11
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

12. 12
Automation-Induced Complacency
System 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
0
0.2
0.4
0.6
0.8
1
1 2 3 4 5 6 7 8 9 10 11 12
Constant
Variable
Total Automation Failure
0
Probabilityofdetecting
systemmalfunction
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)

13. 13
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