Displays
INSY 3020/7976/ENH 670
Display
Any method for presenting information which
uses some intervening mechanism or device to
convey information from its source to the person.
Types of Displays
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When designing displays, consider 3 levels of
representation
1. The physical (real world) system-human, machine,
and environmental characteristics
2. The users internal representation (internal model)
3. The critical interface between 1 and 2 – the display
surface upon which changes in the system are
presented to the user
Display Design
• Our goal is to apply what we know about
sensation and perception to the design of
displays.
• Displays are supposed to present information.
Visual vs. Auditory
• Use visual if:
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Complex message.
Long message.
It needs to be seen later.
Does not need immediate action.
The environment is noisy (sounds).
Visual vs. Auditory
• Use auditory if:
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The message is short and simple.
Not referred to later.
Immediate action.
Overburdened with visual information.
Visual Displays
• Static (e.g., signs) vs. dynamic (e.g., gauges).
• Use depends on information being conveyed +
environment.
Static Displays
• Overall influences on effectiveness:
– Conspicuity: How well it attracts attention.
Influences:
• Be where people are looking.
• Stand out to increase chances of fixation on the fovea.
• Few distracters (or consider them in design).
– Feature search: Pop-out, fast ,easy.
– Conjunction search: Demands attention, slow, hard.
• Example: Central mounted brake light.
Static Displays
• Effect of distracters:
– Feature search (find the blue S):
TXTXXXT
XTXXTXT
TXTXTSX
TXXXTTX
– Conjunction search (find the green T):
TXTXXXT
XTXTTXT
TXTXTTX
TXXXTTX
Static Displays
• Overall influences on effectiveness:
– Visibility: Visible under all viewing conditions.
– Legibility: How easily perceived it is. Influences:
• Contrast ratio (black on white best).
• Font.
Static Displays
• Overall influences on effectiveness:
– Readability: Function of:
• Intelligibility: Clear, few words, no abbreviations,
precise.
• Emphasis: Make the important parts stand out.
• Standardization: Use standards where possible (e.g.,
red).
– Avoid ambiguity. For example:
GATE
1-5
6-10
Example
Original Sentence:
New and Improved Sentence:
Static Displays
• Alphanumeric displays:
– Used to convey detailed information.
– Possible drawbacks:
• Confusability of symbols. Combining into words and
sentences makes this less of a problem.
• Operator must be literate.
Static Displays
• Alphanumeric displays:
– Influences on perceptibility:
• Contrast ratio: High is good.
• Optimize stroke width for situation (e.g., color
combinations).
• Size: Optimize.
• Poorer contrast ratio can be offset with larger size, and
smaller size can be offset with higher contrast ratio.
Static Displays
• Alphanumeric displays:
– Influences on perceptibility:
• Font: Three types:
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Serif (this font).
Sans serif (this font).
Script (this font).
Other.
Serif is generally easier to perceive because it contains more
information.
Static Displays
• Alphanumeric:
– Influences on perceptibility:
• Display format:
– Density (total area): How much of the display area is covered.
Keep this low.
– Density (local): Density immediately surrounding a character.
Intermediate is good.
– Grouping. Helps if the grouping is relevant.
– Layout complexity: Too much hampers performance.
Dynamic Displays
• Display information that changes over time
(fuel level, mileage, heading).
• Can be analog or digital:
– Digital preferred for reading exact values.
• Trend requires memory
– Analog:
• Can be a fixed background with a moving pointer or a
moving background with a fixed pointer.
• Preferred for qualitative readings (trend), check reading,
setting values, tracking, and spatial orientation.
Guideline for Designing Analog Displays
1. Understand all the information needs of the user.
2. A moving pointer against a fixed scale is a preferred design.
3. Do not mix types of pointer (moving elements) indicators when they are
used for related functions
4. A numerical increase in a parameter should be associated with a naturally
expected movement on the display
5. In manually controlled displays, the control (lever, knob) should move the
pointer, not the scale
6. Use a moving pointer-fixed scale display when slight, variable movements
or changes in a system parameter are important.
Dynamic Displays
• Optimal arrangements:
– Frequency of use principle: The ones needed the
most should be easily fixated on the fovea.
– Sequence of use principle: Arrange to minimize
eye movements. Use link analysis to figure this
out.
– Gestalt grouping principles: Group like functions
together.
Visual Displays
• Signal and warning lights:
– Classify possible messages on this scale:
• Warning: Immediate attention and immediate response.
• Caution: Immediate attention, rapid response.
• Advisory: Increase awareness of situation.
– Arrange information to make the most important the most
visible.
• Center (foveal), large, bright, high contrast, flashing (that’s why the
blink feature in html is annoying).
• Use standards and background knowledge consistently. For
example, red for warnings, yellow for caution (reversing that slows
responding).
Display Compatibility
• Degree to which codes and symbols in the display
correspond to the conceptual association of people
• The degree to which the position and location of
display information agrees with the user’s “mental
model” of the system.
• The relationship between the movement of the
display and the response of the system.
Display Conceptual Compatibility
• America’s 1st permanent
repository for high level of
radioactive waste
• US DOE needs to design a
system of markers and
monuments to ward off
intruders from the site
• Displays must be effective
through the year 12000 AD
Yucca Mountain
Example:
Moving Pointer
Fixed Pointer
Fixed Scale
Moving Scale
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200
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200
100
100
100
0
0
0
Orientation
Compatibility
Violated
Summary
• What we learned about sensation, perception,
and information theory has a big impact on
optimal display design. Failing to pay
attention to these facts will result in system
failure.