Human Factors Issues
Chapter 8
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
Refrigerator Example
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 trainin
g
Display area
Control knobs/switche
s
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
Crucial Pieces of Human Factors Process
Safety
Should reflect system and personnel safety factors
Failures Fail safe Failure indications
Standards- ANSI, AAMI, ISO
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!
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
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
Labeling?
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
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