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Transcript of Displays Chapter 8 Introduction to Human Factors Engineering IEE 437/547 Arizona State University...
Displays
Chapter 8
Introduction to Human Factors EngineeringIEE 437/547 Arizona State UniversityOctober 17, 2011
Rebecca W. Boren, Ph.D.
What are displays?
Human-made artifacts designed to support the perception of relevant system variables and further processing of that information.
Ways of Classifying Displays
Physical properties The tasks they are designed to
support Properties of the human user that
dictate the best mapping between display and task (what we learned from the chapters on vision, hearing, and cognition)
Ways of Classifying Displays
Physical properties: Color or monochrome Visual or auditory modality 3-D display or stereo
Ways of Classifying Displays
The tasks they are designed to support: Navigating Controlling Decision Making Learning So forth…
Ways of Classifying Displays
Properties of the human user that dictate the best mapping between display and task: Thirteen principles of display design
Perceptual principles Mental model principles Principles based on attention Memory Principles
Make displays legible (or audible)
Good contrast Font size and type How far away will the display be
viewed? Use the principles for vision (ch 4)
and audition (ch 5) Example: ClearviewHwy Fonts
Avoid absolute judgment
Do not require users to judge the level of a variable on the basis of a single sensor variable like color or size, which contains more than five to seven possible levels.
What variable is used to differentiate these screwdrivers?
Does it conform to the Principle of Avoiding Absolute Judgment?
Answer: Length
Top-down processing
People will perceive and interpret signals in accordance with what they expect to perceive on the basis of past experience.
WARNING
Redundancy gain When the same
message is expressed more than once, particularly if the presentation is in alternative physical forms. (In this case, color and words.)
Problem With the design on the left, the two displays are very similar, but represent two very different quantities. Both displays have the same numeric scale with the same incremental increases. This can cause driver confusion.
SolutionTo eliminate confusion, the tachometer and speedometer should be on different numeric scales, like the display on the right.
Bad Good
Principle of the moving part
Safety Blanket
•Uses 4 AA batteries and car plug •4 lighting modes: arrows flashing in sequence, all arrows flashing simultaneously, all arrows on at the same time, reflectors only (lights off)
http://www.astrooptics.com/emergency.html
Minimizing information access cost
Cost is measured in time and effort of the user. Keep frequently accessed sources in such a location that the cost of traveling between them is small.
Proximity compatibility principle
Sometimes two or more sources of information must be mentally integrated to complete the task. Parts of the information should be close together, but not too close.
Principle of multiple resources
Dividing information display between modalities (audition and vision).
Multiple cues to identification. Icons accompanied by words.
Replace memory with visual information: Knowledge in the World
Visible reminders or statements of what is to be done.
Computer on the right with labelsFor each device: E:, A:, D:, F:, G:.
Alerting Displays
Three levels of alerts Warning: most critical category;
signaled by the most salient auditory alerts.
Cautions: less critical, softer auditory alert.
Advisories: need not be auditory. Can be visual.
Alerting Displays
Aviation community has agreed on a common color code: Red for warning Amber or yellow for caution Other colors (that cannot be confused
with red or amber) for advisory information.
Labels
Purpose is to signal the identity or function of an entity.
Represents “knowledge in the world” Usually print, but can be an icon.
Design criteria for labels:
Visibility/legibility (contrast sensitivity) Discriminability (try to avoid Don’t) Meaningfulness (avoid icons only or
abbreviations) Location (should be located physically
close to the entity)
Design criteria for monitoring displays
Legibility Analog versus digital If analog is chosen, the orientation of
the display scale should be in a form and direction that is congruent with the user’s mental model.
Up or right shows increase.
Prediction Prediction is not something humans
do very well, particularly under stress. A good predictor display can aid human performance. Do not try to predict further into the future than is reasonable and necessary.
Sluggishness can be a problem.
Design criteria for multiple display layouts
Frequency of use. Most frequently used displays should be
adjacent to the PVA.
Display relatedness or sequence of use.
Navigation Displays serve to
Provide guidance about how to get to a destination.
Facilitate planning Help recovery if the traveler becomes
lost. Maintain situation awareness
regarding the location of a broad range of objects.
Electronic Maps
With electronic maps, detail can be achieved without sacrificing legibility if zooming capabilities are incorporated.
The Problem with Clutter Clutter slows down the time to access
information Slows down the time to read items, as
a consequence of masking by nearby items.
Solutions to the Problem of Clutter
Effective color-coding Minimalist maps With electronic maps it is possible to
highlight needed information A “you are here” or YAH indication is
useful
Tables & Graphs
Decide how best to display data Legibility and clutter are issues. “Greatest amount of data with the
least amount of ink”
Other Display Modes
The most common forms of display are visual and auditory. Occasionally, touch and smell are used to alert us.
Olfactory Displays
Olfactory relates to the sense of smell.
Natural gas does not have any odor. A stinky smell is added to warn of a gas leak.
IF THE RED LIGHT IS BLINKING OR YOU SMELL WINTERGREEN – EVACUATE THE BUILDING
In buildings where carbon dioxide is released when a fire is detected, an odor of wintergreen was added to the gas as a warning.
E. J. McCormick & M. S. Sanders, Human Factors in Engineering and Design, 5th Ed., 1982, p. 150.
Tactile Displays
Bott’s Dots are used on the highway to mark the lanes.
They are also used on the race track to help the drivers stay on course.