Human Factors Issues

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Human Factors Issues

• Chapter 8

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What is Human Factors?

• Application of the scientific knowledge of human
  capabilities and limitations to the design of
  systems and equipment to produce products with
  the most efficient, safe, effective, and reliable
  operation

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Human Factors

• Interface points
• Environment
• Skill level of user
• Interaction between
• Human element
• Hardware element
• Software element

Refrigerator Example
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Human Element

• Memory
• Long term
• Short term
• Thinking and reasoning
• Visual perception
• Dialogue construction
• Individual skill level
• Individual sophistication

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Size limitations
Location of controls
Possible user training
Compatibility with other equipment
Hardware Element
Control knobs/switches
Potential need for portability
Display area
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Simple, reliable data entry
Displays must not be overcrowded
Software Element
Feedback to users
Menu driven
Dialogue must be jargon-free
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Human Factors Process

• Analytic process that focuses on device
  objectives
• Design and development process that converts
  results of analyses into detailed equipment
  features
• Test and evaluation process which verifies that
  development process satisfies constraints

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Steps in Human Factors Process

• Planning
• Analysis
• Conduct user studies
• Observations
• Interviews
• Focus groups
• Task analysis
• Benchmark usability tests
• User profile
• Setup advisory panel

Crucial Pieces of Human Factors Process
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Safety

• Should reflect system and personnel safety
  factors
• Failures
• Fail safe
• Failure indications
• Standards- ANSI, AAMI, ISO

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Documentation

• Written to meet needs of various target
  populations
• Study capability and information needs of
  documentation users
• Mental abilities
• Physical abilities
• Previous experience
• Understanding of general operation
• Special needs of environment

Attempt to avoid this!
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Anthropometry

• Science of measuring human body and its parts and
  functional capacities
• Range of values 5th percentile female to 95th
  percentile male
• Functional dimensions
• Psychological elements
• Workstation design considerations

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Labeling

• Labels should be clear and direct
• Controls, displays, and other equipment that must
  be located should be clearly marked
• Receptacles and connectors should be marked with
  intended function or connection
• Hazard warnings should be prominent

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Labeling?
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Software

• Every user input should consistently produce some
  perceptible response from the computer
• Log-on should be automatically completed before
  any operation
• Allow for orderly shutdown in case of failure

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Data Entry

• Consistent data entry transactions
• Minimize user input actions
• Feedback to user about acceptance or rejection of
  an entry
• Ability to change entry after it has been added

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Feedback

• Present status, information, confirmation, and
  verification throughout the interaction
• Standby should be accompanied by WAIT message
• Feedback should be self-explanatory

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Prompts

• Commands, error messages, system capabilities,
  and procedures should be explained with prompts
  or help instructions
• Missing data/aborting changes should be prompted
• Factual and informative dialogue
• Displayed in standardized area

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Defaults

• Currently defined default values should be
  provides and automatically displayed
• User should be prompted for acceptance of
  defaults
• Users should be able to set their own default

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