Chapter 8: Displays Wickens

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Chapter 8 DisplaysWickens

• IE 8541 Intelligent Decision Support Systems

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Power Plant Emergency Scenario

• A power plant operator is monitoring the plant
  from the control room
• An alarm sounds
• Many warning tiles are lit up, but no pattern
  is apparent.
• Gauges (below warning tiles) show no pattern.
  Some are out of range. But not clear how gauges
  connect to warning tiles.
• Manual shows clear flow diagram of plant
• Page on warning lights in separate place at back
  of manual,
• Emergency procedures are found on yet another
  page.
• Operator gives up and shuts down whole plant!!
  Very costly.

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Challenges

• Operator must try to integrate 5 separate sources
  of information warning tiles, gauges, 3
  different parts of the manual.
• The displays did not help the operator to
  interpret or integrate complex information.

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The Role of Displays
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Displays

• Artifacts designed to support
• Perception of relevant system variables
  (situation awareness SA)
• Facilitate further processing of information
• Facilitate formation of task and context
  appropriate abstractions and concepts
• Facilitate integration of information

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Types of Displays

• A display does not have to be associated with a
  computer (example speedometer on car, knob on
  gas stove position shows current setting).
• A display can be static e.g. road signs
• Displays may be visual, auditory, haptic (touch),
  etc. Examples
• Visual Flashing light on ambulance,
• Auditory siren on ambulance,
• Haptic cell phone in vibrate mode.
• Smell Odor-rama in movie theater with scratch
  and sniff card.

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Designing Displays

• First steps are
• Identify task
• Identify goals
• Perform a detailed information analysis

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Principles of Display Design (grounded in
strengths and weaknesses of human information
processing)

• Perception
• Make displays legible/audible
• Avoid absolute judgment limits
• Facilitate top-down processing by providing
  context
• Use redundancy to reduce errors display in
  several forms.
• Discriminability make options easy to distinguish

• Mental Models
• Pictorial realism displays should look like the
  variables they represent.
• Principle of moving parts elements of display
  should move in a way compatible to users mental
  model

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Mental models Principle of pictorial
realismDisplay should be consistent with mental
model
Not consistent!
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Principles of Display Design

• Attention
• Minimize information access cost, particularly
  when information must be integrated,
• Proximity compatibility two sources of info that
  must be integrated must be made close and/or
  compatible.
• Principle of multiple resources can be helpful
  to use multiple sensory channels

• Memory
• Use external (usually visual) memory aids to
  reduce load on STM.
• Aid people in predicting future events, so they
  may be proactive, rather then reactive.
• Consistency.