1. (the represented system)
Chapter 8: Displays
Attention
Display
(the represented system)
Perception
Mental model
Senses
System

2. Objectives Power of representation
Display variables and the match to the task
Display design principles
Perceptual
Mental model
Attention
Memory
Types of displays and how to apply the principles

3. Power of representation
A good representation captures essential elements and leaves out the rest
Good representations allow people to concentrate on essential elements and ignore the irrelevant
Poor representations can be misleading, out of sight out of mind
Solving a problem simply means representing it so as to make the solution transparent (Simon, 1981)

4. Game of 15
Using digits 1,2,3,4,5,6,7,8,9
Each player takes a digit in turn
Once a digit is taken it cannot be used by the other player
The first player that has three digits that sum to 15 wins
Sample game: Player A takes 8, Player B takes 2, A takes 4, B takes 3, A takes 5
What should B do?

5. Player A = X, Player B=O O X X X O

6. Player A, Player B 3 8 4 9 5 1 6 2 7

7. Displays: Applications
Internet
Cockpits
Cars
Maps
Control rooms …

8. Display variables Location (superimposed) Color
Dimensionality (2-D vs 3-D)
Motion (what and how)
Intensity (contrast between elements)
Modality (e.g., visual vs. auditory)
Coding (e.g., analog vs. digital)
No one best display configuration, but depends on the match to the task

9. Display principles
Display principles: General strategies for improving display effectiveness though consideration of human limits and capabilities
Categories of principles:
Perceptual
Mental model
Attention
Memory

10. Display design principles
Perceptual principles
1) Absolute judgement (maximum of 5-7 levels)
2) Top-down processing (Highlight the unexpected)
3) Redundancy gain (Multiple cues or modes)
4) Discriminability (ratio of similar to dissimilar features)
Attention principles
5) Minimizing information access cost (minimize “distance” between variables)
6) Proximity compatibility principle (link variables through common location, color, or other code)
7) Principle of multiple resources (distribute information between mental resources)
Mental model principles
8) Principle of pictorial realism (configure to match system/mental model, thermometer)
9) Principle of the moving part (match movement to system/mental model, aircraft and altimeter)
10) Ecological interface design (display provides an externalized and normative mental model)
Memory principles
11) Predictive aiding (show future states rather than force people to estimate)
12) Knowledge in the world (displayed information rather than rely on memory)
13) Consistency (same cues should have same meaning, red is for danger)

11. Perceptual principles
Absolute judgement (maximum of 5-7 levels)
Top-down processing (Highlight the unexpected)
Redundancy gain (Multiple cues or modes)
Discriminability (ratio of similar to dissimilar features)

12. What is wrong with this graph

13. Problems of discriminability