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Human Factors Issues. Chapter 8 Paul King. 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. Human Factors.
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Human Factors Issues Chapter 8 Paul King
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
Human Factors • Interface points • Environment • Skill level of user • Interaction between: • Human element • Hardware element • Software element
Human Element • Memory • Long term • Short term • Thinking and reasoning • Visual perception • Dialogue construction • Individual skill level • Individual sophistication
Hardware Element • Size limitations • Location of controls • Compatibility with other equipment • Potential need for portability • Possible user training • Display area • Control knobs/switches
Software element • Simple, reliable data entry • Menu driven • Displays must not be overcrowded • Dialogue must be jargon-free • Feedback to users
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
Steps in Human Factors Process • Planning • Analysis • Conduct user studies • Observations • Interviews • Focus groups • Task analysis • Benchmark usability tests • User profile • Setup advisory panel
Steps in Human Factors Process (cont.) • Set usability goals • Provide quantitative basis for acceptance testing • Objective or subjective • Design user interface concepts • Develop conceptual model • Develop user interface structure • Define interaction style • Develop screen template • Develop hardware layout • Develop final design
Steps in Human Factors Process (cont.) • Model the user interface • Build a prototype to evaluate dynamics of user interface • Test user interface • At start of development effort • When prototype is developed • When marketing claims may be displayed
Specifying the User Interface • Style guide • Screen hierarchy map • Screenplay • Specification prototype • Hardware layouts
Additional Human Factors Design Considerations • Consistency and simplicity • Safety • Environmental/Organizational Considerations
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
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
Alarms and Signals • Purpose is to draw attention of operator • 3 categories: • High priority: immediate response required • Red flashing light • Medium priority: prompt response required • Yellow flashing light • Low priority: awareness required • Steady yellow light • Audible signal when not in line of sight
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
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
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
Displays • Visual displays should clearly indicate system status • Graphic displays should be used when perception of pattern of variation is important • Numeric displays should be sued when quantitative accuracy is important • Displays should be consistent
Interactive Control • System response times should be consistent with operational requirements • Control-display relationships should be straightforward and explicit • Menu selection for interactive controls
Feedback • Present status, information, confirmation, and verification throughout the interaction • Standby should be accompanied by ‘WAIT’ message • Feedback should be self-explanatory
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
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