Displays

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Displays

• Human Factors Psychology
• Dr. Steve

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Gauges vs. Warnings (idiot lights)
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Perceptual Principles of Display Design

• Absolute Judgment Limits avoid making the
  operator judge the represented variable level on
  the basis of a single sensory dimension (color,
  size, pitch, etc.)
• Top-Down Processing signals are perceived and
  interpreted based on operators past experience

Concentrate!
Click Here for Card Trick Example
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Perceptual Principles of Display Design

• Redundancy Gain presenting a signal in more
  than one way increases the likelihood it will be
  interpreted correctly
• ex NO TURN ON RED
• Discriminability similar appearing signals are
  likely to be confused
• ex Speed or RPM?
• video clip

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Mental Model Principles of Display Design

• Principle of Pictorial Realism Display looks
  like the variable it represents
• Principle of Configural Displays elements are
  configured in same manner as environment it
  represents
• Principle of the Moving Part Moving elements
  should move consistently with the users mental
  model

Some Door Ajar indicators not only tell you
that the door is open, but show you which one
The tape indicator moves in the same direction
the tape is playing to make it easier to know
whether to FF or REW
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Mental Model Principles of Display Design

• Ecological Interface Design Displays that
  closely correspond to the environment (direct
  perception)

• Ecological invariants
• compression horizontal lines appear to get
  closer in distance
• splay angle of convergence of parallel lines
  (shape of runway on descent)
• optical flow when moving objects appear to
  flow from vanishing point
• time to contact rate of optical flow
• global optical flow rate of optical flow in
  relation to ground (motion parallax)
• edge rate flow of parts w/in a texture (rumble
  strips as approach stop sign)

OZ display developed at IHMC
Oz transforms the instrument flying process from
one of complex mental modeling and slow
sequential information gathering to one of
instantaneous direct perception.
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Attention Principles ofDisplay Design

• Minimize Information Access Cost frequently
  accessed sources of info should be readily
  available
• Ex right mouse button (PC) brings up menu of
  common commands
• Proximity Compatible Principle info that needs
  to be integrated or compared
  should be presented close together
  (allows for patterns to emerge)
• Close spatial proximity increases the likelihood
  of parallel processing
• Principle of Multiple Resources facilitate
  processing of info by presenting via more than
  one medium
• Click for example

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Memory Principles of Display Design

• Principle of Predictive Aiding Displays that
  project into the future allow operator
  to be proactive,
  not reactive
• Knowledge in the World Make info visible when
  needed to minimize reliance on memory
• Ex Benefit of menus (Windows) over command
  language (DOS)
• Principle of Consistency Displays should
  present info in a consistent manner
• Ex All MicroSoft programs have same main menu
  (File Edit View)

Predictive display showing where aircraft are
projected to be in a given time
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Alerting Displays

• Warnings most critical signaled by salient
  auditory (omnidirectional) alerts
• Cautions moderately critical may be signaled
  by less salient auditory alerts
• Advisories Least critical may be signaled
  with peripheral cue (visually)

Human Factors implication Could tactile cueing
be used instead of auditory, and if so, how would
you indicate varying criticality levels?
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Color-Coded Warning Scales
Asteroid Threat Scale
Terror Alert Scale
Severe
Critical
Serious
Guarded
Normal
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Labels
Labels static displays of knowledge in the world

• Visibility/Legibility contrast and spatial
  frequency
• Labels are not effective if they cant be read
• Discriminability where details may be easily
  confused, the important features should be
  highlighted
• Ex Warning If swallowed, DO NOT induce vomiting
• Meaningfulness avoid abbreviations and
  icons whenever possible
• Ex Does this sign say go right or dont go
  right?
• Location labels should be close to and
  unambiguously related to the thing to which they
  are
  associated
• Ex difficult to tell what mode this radio is in

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Color Coding

• Problems
• Color discrimination difficult for color blind,
  reduced illumination, etc.
• Cant describe continuous data well ex too
  many colors on weather map
• Must be consistent with user stereotypes or may
  cause more harm than good
• Irrelevant use of color for aesthetics or
  preferences may be confused with coding

• Benefits
• Color stands out against monochrome background
• Colors capitalize on established meanings ex
  reddanger
• Color ties together elements of different
  displays
• Color can speed processing if redundant with
  symbology or text

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Monitoring Displays

• Legibility contrast, spatial frequency, visual
  angle, etc
• Analog vs. Digital Analogs advantage is
  ability to estimate rate of change, while
  digitals advantage is precision of reading
• Display showing redundant
  analog and
  digital signals

• Prediction and Sluggishness for some systems
  the
  effects of input do not show up right
  away, (need prediction displayed to compensate
  for lag)
• Ex Steering a large ship or turning on hot water
  in shower

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Monitoring Displays

• Analog Form and Direction scale and direction
  of movement should be consistent with the users
  mental model
• Requirement for higher numbers at top (or to
  right) and movement of indicator up (or to right)
  for high may sometimes conflict (does scale move
  or indicator?)

Pointer moves up to indicate increasing value
scale fixed (consistent with pictorial realism
and moving parts, but space limitation)
Pointer fixed, scale moves down to indicate
increasing value (violates moving parts
principle, but consistent with pictorial realism)
Pointer fixed, scale moves up to indicate
increasing value with low numbers on top
(consistent with moving parts principle, but
violates pictorial realism)
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Example of Bad Monitoring Display
Not being one to read directions carefully, I
waited 15 minutes for my sons rubber bugs to
cool because I misinterpreted this poorly
designed temperature gauge. The oven was cool for
some time, but like a normal thermometer, I
thought the arrow at the high position meant hot.
Note how the pointer on this toy ovens
temperature gauge goes up as the temperature goes
down (inconsistent with users mental model of
directionality).
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Principles of Display Layout

• Frequency of Use displays used most frequently
  should be placed in the primary visual field
  (PVA)
• Display Relatedness related displays should be
  placed close together
• Consistency placing displays in a standard
  position eases the load on memory and attention
• Organizational Grouping displays spatially
  organized to allow for patterns to emerge
  (pop-out)
• Stimulus-Response Compatibility displays should
  be close to their associated controls
• Clutter Avoidance minimum spacing between
  displays

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Glass Cockpit
Glass cockpits allow the operator the flexibility
to place any display in any CRT location at any
time
Space Shuttles Glass Cockpit

• Guidelines for using glass cockpit displays
• Clearly indicate current display mode
• Use consistent formats
• Do not provide excessive flexibility

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Head-Up Displays (HUD)

• HUD Advantages
• Far and near info may be monitored in parallel
• Imagery can be mapped onto outside environment
• No need to frequently re-accommodate eyes when
  switching from displays to outside view
• Be careful to avoid excess clutter

HUDs superimpose display information on the PVA
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Augmented Reality Displays
Augmented Displays - display that improves upon
reality by superimposing info over actual
environment ex thermal imaging color codes
objects by temperature
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Navigation Displays Maps

• Navigation Displays Maps
• Direct user to destination (path)
• Facilitate planning
• Help recover from being lost
• Maintain situation awareness (build mental map)
• Guidelines
• Legibility adequate text size
• Avoid excessive clutter
• You are here personal-referenced view aids lost
  recovery
• Best if North-up and Nose-up options are available

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Spatial Knowledge

• Levels of Spatial Knowledge
• Landmark Knowledge (egocentric) learned route
  by landmarks
• Look for Hardees then turn right past the duck
  pond
• Requires least mental effort, but useless when
  lost
• Route Knowledge (egocentric) route list or
  commands of how to get from point A to B.
• Go 3 miles turn left, 4 miles then turn right,
  etc.
• Survey Knowledge (exocentric) map knowledge,
  layout of environment
• Well developed mental map allows one to visualize
  spatial relations
• Requires most mental effort, but useful when lost

Move from 1 to 2 to 3 with increased experience
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Virtual Reality for Developing Spatial Knowledge

• Virtual Reality Fooling people into accepting
  as real what is only perceived (Karen Carr)
• Egocentric Navigation (may also provide
  exocentric)
• Immersive (eye view) or tethered (view from
  outside body)
• Proprioceptive cues
• Head-tracking (with HMD)
• 3-D viewing
• Dynamic
• Interactive

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Virtual Environments/RealityBenefits/Costs

• Benefits of VE/VR
• Telepresence
• Hi Fidelity Training
• Military, medical applications
• On-line Comprehension
• 3-D interaction with spaces
• Escape from Reality
• Distraction from pain
• Knowledge Elicitation
• Experts explain as they do

• Costs of VE/VR
• Costly
• Realistic motion is difficult
• Distorted perception
• Limited FOV
• Disorientation
• Cybersickness

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Displays used for Training
Joint Combat Advanced Display and Debriefing
System (JCADDS)