1. CEN3722 Human Computer Interaction Displays
Dr. Ron Eaglin

2. Objectives Describe the following display principles
Perceptual operations
Mental models
Attention
Memory
Describe principles behind alerting displays, including:
Warnings
Cautions
Advisories
Describe principles underlying appropriate labeling

3. Objectives Describe the following display principles Pictorial realism
Moving part
Redundancy gain
Discriminability
Proximity compatibility
Predictive aiding
Knowledge in the world
Consistency

4. Displays
Human made artifacts designed to support the perception of relevant systems variables and facilitate processing of that information
Visual
Graphs
Speedometer
Gauges
Print
Auditory
Buzzers
Beeps

5. Display Variables Location Color Dimensionality Motion Intensity
Coding
Modality
What to display

6. Display - Example
23.445 98
23.11 4 12
1245

7. Display Example
23.445 98
23.11 4 12
1245

8. Display Principles Perceptual operations Mental model Human attention
Human memory

9. Perceptual Principles
Avoid absolute judgment limits
Do not require operator to judge the level of a variable on the basis of a single sensory variable like color, size, or loudness, with numerous levels.
IF light is royal blue, THEN all systems are GO

10. Perceptual Principles
Top-down processing
Users perceive and interpret signals in accordance with what they expect to perceive on the basis of past experience
Valve 12 is OK
Valve 13 is OK
Valve 14 is OK
Valve 15 is OFF
Valve 16 is OK
Valve 12 is OK
Valve 13 is OK
Valve 14 is OK
Valve 15 is OFF
Valve 16 is OK

11. Perceptual Principles
Redundancy Gain
Messages expressed multiple times are more likely to be interpreted correctly.
Best if multiple messages are in alternative forms (e.g., visual AND aural channels).
WARNING
WARNING
Color Only
Color +
Label
Color +
Label +
Auditory

12. Perceptual Principles

13. Perceptual Principles
Discriminability: Similarity causes confusion
Signals that are similar will be confused
Either at time they are perceived or if signals must be kept in working memory
Similarity affected by ratio of similar to dissimilar features:
J606V45 versus J706V45
5 similar, 1 dissimilar
606 versus 706
2 similar, 1 dissimilar

14. Perceptual Principles
This figure illustrates how
the growth of large
companies has increased
over the last few years.
This figure illustrates how
the growth of large
countries has increased
over the last few years.

15. Perceptual Principles
Companies
Countries
This figure illustrates how
the growth of large
companies has increased
over the last few years.
This figure illustrates how
the growth of large
countries has increased
over the last few years.

16. Mental Model Principles
Principle of Pictorial Realism (Display should look like variable it represents)
100
100

17. Mental Model Principles
Principle of the Moving Part - Moving elements of any display of dynamic information should move in a spatial pattern and direction that is compatible with the user’s mental model of how the represented element moves. (follow user mental model)
375
400
425
450
475
500
430
525
465
500
525
475
500
450
475
400
465
425
450
400
425
375
400

18. Mental Model Principle
Ecological Interface Design
Use principles of pictorial realism and moving part to create display with close correspondence with real world system
Consistent with/create operator mental model

19. Mental Model Principles
Time 1
Time 2
340
260
110
Reservoir : 340
Reservoir : 330
Holding: 260
Holding: 270
Valve Open
Flow:110 p/m
Reservoir
Flow: 0 p/m
Holding Area
Valve: Open
Valve: Closed
330
270
Pictorial Realism
Moving Part
Redundancy Gain
Valve Closed
Reservoir
Holding Area

20. Attention Principles
Minimizing information access cost - There is a mental cost associated with the time or effort to move selective attention from one display location to another to access information
Good designs minimize cost by keeping frequently accessed information sources in a prominent place

21. Attention Principles Proximity compatibility principle
When two or more sources of information are related, and must be mentally integrated to complete a task (through divided attention), then they should be placed contiguously in space
“Close mental proximity” requires “close display proximity”

22. Attention Principles Focused attention Divided attention
Allows information sources to be perceived without distraction from other information sources
Divided attention
Allows parallel processing of two or more information sources
Selective attention
Attention shifts based on salience of incoming information.

23. Proximity Compatibility Principle

24. Attention Principles + Principle of multiple information resources
Processing a large amount of information can be facilitated by dividing information into multiple channels
Visual +
Visual
Audio

25. Memory Principles Principle of predictive aiding
Predicting future is hard
Current conditions
Possible future conditions
Rules that map (relate) the two
As a result, human operators become reactive rather than proactive
React to events after the fact versus anticipating events.
Replace “current status” display with predictive display
Allows operators to rely on perceptual versus cognitive processing

26. Memory Principles Principle of knowledge in the world
Information prominently displayed
Recognition versus recall: Visibility
Knowledge in the head requires relying on retrieval from long term memory
Graphical user interface versus command line

27. Memory Principles Principle of consistency
Display information consistently
Across multiple displays/windows/screens.
Make behavior consistent
Exit shortcut: Exit versus Exit

28. Alerting Displays System alerts differ by criticality
Severity of the consequences for ignoring them
Warnings
Most critical
Use auditory AND visual alert

29. Alerting Displays Cautions
Same as warning, use both auditory and visual signal
Less salient auditory signal (“softer” sound)

30. Alerting Displays Advisories Least critical
Need not include auditory signal (only visual)

31. Labels Used to unambiguously identify elements
Present “knowledge in the world

32. Label Design Principles
Visibility/legibility
Contrast sensitivity a concern
Contrast sufficient so that label can be read in poorest of conditions

33. Label design Principles
Discriminability
Operator should be able to clearly discriminate between labels
Relates to distinct features

34. Label Design Principles
Discriminability
Tendency to confuse negative and positive labels
Problem under degraded sensory conditions
Low visibility for visual indicators
Noisy environments for auditory warnings

35. Labels Meaningfulness
No guarantee that a particular word or icon triggers the appropriate meaning, even if it is visible and legible.
Avoid labels based solely on icons or abbreviations

36. Objectives Describe the following display principles
Perceptual operations
Mental models
Attention
Memory
Describe principles behind alerting displays, including:
Warnings
Cautions
Advisories
Describe principles underlying appropriate labeling

37. Objectives Describe the following display principles Pictorial realism
Moving part
Redundancy gain
Discriminability
Proximity compatibility
Predictive aiding
Knowledge in the world
Consistency