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Displays. Human Factors Psychology Dr. Steve. Gauges vs. Warnings (idiot lights). I have removed the card you were thinking about. Think about one card and remember it, then click. Perceptual Principles of Display Design.

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Human Factors Psychology

Dr. Steve

Gauges vs warnings idiot lights
Gauges vs. Warnings (idiot lights)

Perceptual principles of display design

I have removed the card you were thinking about

Think about one card and remember it, then click

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 operator’s past experience


Click Here for

Card Trick Example

Perceptual principles of display design1
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

Mental model principles of display design
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 user’s 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

Mental model principles of display design1
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.”

Attention principles of display design
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

Memory principles of display design
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

Alerting displays
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?

Color coded warning scales
Color-Coded Warning Scales

Asteroid Threat Scale

Terror Alert Scale







Labels– static displays of knowledge in the world

  • Visibility/Legibility– contrast and spatial frequency

    • Labels are not effective if they can’t 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 don’t 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

C o l o r c o d i n g


  • Color stands out against monochrome background

  • Colors capitalize on established meanings ex: red=danger

  • Color ties together elements of different displays

  • Color can speed processing if redundant with symbology or text


  • Color discrimination difficult for color blind, reduced illumination, etc.

  • Can’t 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

Monitoring displays
Monitoring Displays

  • Legibility – contrast, spatial frequency, visual angle, etc

  • Analog vs. Digital – Analog’s advantage is ability to estimate rate of change, while digital’s 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

Monitoring displays1













Monitoring Displays

  • Analog Form and Direction – scale and direction of movement should be consistent with the user’s 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)

Example of bad monitoring display
Example of Bad Monitoring Display

Not being one to read directions carefully, I waited 15 minutes for my son’s 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 oven’s temperature gauge goes up as the temperature goes down (inconsistent with user’s mental model of directionality).

Principles of display layout
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

Glass cockpit
Glass Cockpit

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

Space Shuttle’s Glass Cockpit

  • Guidelines for using glass cockpit displays:

  • Clearly indicate current display mode

  • Use consistent formats

  • Do not provide excessive flexibility

Head up displays hud
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

Augmented reality displays
Augmented Reality Displays

  • Augmented Displays - display that improves upon reality by superimposing info over actual environment

    • ex: thermal imaging color codes objects by temperature

Navigation displays maps
Navigation Displays & Maps

Navigation Displays & Maps:

  • Direct user to destination (path)

  • Facilitate planning

  • Help recover from being lost

  • Maintain situation awareness (build mental map)


  • 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

Spatial knowledge
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

Virtual reality for developing spatial knowledge
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

Virtual environments reality benefits costs

Benefits of VE/VR


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


Realistic motion is difficult

Distorted perception

Limited FOV



Virtual Environments/RealityBenefits/Costs

Click button for Virtual Tour of Legoland


Displays used for training
Displays used for Training

Joint Combat Advanced Display and Debriefing System (JCADDS)