DisplaysDisplaysHuman Factors PsychologyHuman Factors Psychology

Dr. SteveDr. Steve

Perceptual Principles of Perceptual Principles of Display DesignDisplay Design Absolute Judgment LimitsAbsolute Judgment Limits – avoid making the operator – avoid making the operator

judge the represented variable level on the basis of a judge the represented variable level on the basis of a single sensory dimension (color, size, pitch, etc.)single sensory dimension (color, size, pitch, etc.)

Top-Down ProcessingTop-Down Processing – signals are perceived and – signals are perceived and interpreted based on operator’s past experienceinterpreted based on operator’s past experience

Concentrate!Click Here forCard Trick Example

Think about one card and remember it, then clickI have removed the card you were thinking about

Perceptual Principles of Perceptual Principles of Display DesignDisplay DesignRedundancy GainRedundancy Gain – – presenting a signal in more presenting a signal in more than one way increases the than one way increases the likelihood it will be interpreted likelihood it will be interpreted correctlycorrectly

ex: NO TURN ON ex: NO TURN ON REDRED

DiscriminabilityDiscriminability – similar – similar appearing signals are likely to appearing signals are likely to be confusedbe confused

ex: Speed or RPM?ex: Speed or RPM?

Mental Model Principles of Mental Model Principles of Display DesignDisplay Design Principle of Pictorial RealismPrinciple of Pictorial Realism – Display looks like the – Display looks like the

variable it represents variable it represents Principle of Configural DisplaysPrinciple of Configural Displays – elements are configured in – elements are configured in

same manner as environment it representssame manner as environment it represents

Principle of the Moving PartPrinciple of the Moving Part – Moving elements should – Moving elements should move consistently with the user’s mental modelmove consistently with the user’s mental model

The tape indicator moves in the same direction the tape is playing to make it easier to know whether to FF or REW

Some “Door Ajar” indicators not only tell you that the door is open, but show you which one

Mental Model Principles of Mental Model Principles of Display DesignDisplay Design

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

“Oz transforms the instrument flying process from one of complex mental modeling and slow sequential information gathering to one of instantaneous direct perception.”

OZ display developed at IHMC

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

Attention Principles ofAttention Principles ofDisplay DesignDisplay Design

Minimize Information Access CostMinimize Information Access Cost – frequently accessed – frequently accessed sources of info should be readily availablesources of info should be readily available Ex: right mouse button (PC) brings up menu of common commandsEx: right mouse button (PC) brings up menu of common commands

Proximity Compatible PrincipleProximity Compatible Principle – info that needs – info that needs to be integrated or compared should be presented to be integrated or compared should be presented close together (allows for patterns to emerge)close together (allows for patterns to emerge) Close spatial proximity increases the likelihood of parallel Close spatial proximity increases the likelihood of parallel

processingprocessing Principle of Multiple ResourcesPrinciple of Multiple Resources – facilitate processing of info – facilitate processing of info

by presenting via more than one mediumby presenting via more than one medium Click for exampleClick for example

Memory Principles of Memory Principles of Display DesignDisplay Design Principle of Predictive AidingPrinciple of Predictive Aiding – Displays that – Displays that

project into the future allow operator to project into the future allow operator to be proactive, not reactivebe proactive, not reactive

Knowledge in the WorldKnowledge in the World – Make info visible when needed – Make info visible when needed to minimize reliance on memoryto minimize reliance on memory Ex: Benefit of menus (Windows) over command language (DOS)Ex: Benefit of menus (Windows) over command language (DOS)

Principle of ConsistencyPrinciple of Consistency – Displays should present info in – Displays should present info in a consistent mannera consistent manner Ex: All MicroSoft programs have same main menu (File Edit View)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 DisplaysAlerting DisplaysWarnings Warnings – most critical – signaled by salient – most critical – signaled by salient

auditory (omnidirectional) alertsauditory (omnidirectional) alerts

CautionsCautions – moderately critical – may be signaled – moderately critical – may be signaled by less salient auditory alertsby less salient auditory alerts

AdvisoriesAdvisories – Least critical – may be signaled – Least critical – may be signaled with peripheral cue (visually)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?

Asteroid Threat Scale

Normal

Guarded

Serious

Critical

Severe

Terror Alert Scale

Color-Coded Warning Color-Coded Warning ScalesScales

LabelsLabels Visibility/LegibilityVisibility/Legibility – contrast and spatial frequency– contrast and spatial frequency

Labels are not effective if they can’t be readLabels are not effective if they can’t be read DiscriminabilityDiscriminability – where details may be easily confused, the – where details may be easily confused, the

important features should be highlightedimportant features should be highlighted Ex: Ex: Warning: If swallowed, Warning: If swallowed, DO NOTDO NOT induce vomiting induce vomiting

MeaningfulnessMeaningfulness – avoid abbreviations and – avoid abbreviations and icons whenever possibleicons whenever possible Ex: Does this sign say go right or don’t go right?Ex: Does this sign say go right or don’t go right?

LocationLocation – labels should be close to and unambiguously – labels should be close to and unambiguously related to the thing to which they related to the thing to which they are associatedare associated Ex: difficult to tell what mode this radio is inEx: difficult to tell what mode this radio is in

LabelsLabels – static displays of knowledge in the world– static displays of knowledge in the world

CCoolloorr CCooddiinnggBenefitsBenefits

Color stands out against Color stands out against monochrome backgroundmonochrome background

Colors capitalize on established Colors capitalize on established meanings meanings ex: ex: redred=danger=danger

Color ties together elements of Color ties together elements of different displaysdifferent displays

Color can speed processing if Color can speed processing if redundant with symbology or redundant with symbology or texttext

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

Can’t describe continuous data Can’t describe continuous data well well ex: too many colors on weather ex: too many colors on weather mapmap

Must be consistent with user Must be consistent with user stereotypes or may cause more stereotypes or may cause more harm than goodharm than good

Irrelevant use of color for Irrelevant use of color for aesthetics or preferences may be aesthetics or preferences may be confused with codingconfused with coding

Monitoring DisplaysMonitoring Displays Legibility Legibility – contrast, spatial frequency, visual angle, etc– contrast, spatial frequency, visual angle, etc Analog vs. DigitalAnalog vs. Digital – Analog’s advantage is ability to – Analog’s advantage is ability to

estimate rate of change, while digital’s advantage is estimate rate of change, while digital’s advantage is precision of readingprecision of reading Display showing redundant Display showing redundant

analog and digital signalsanalog and digital signals

Prediction and SluggishnessPrediction and Sluggishness – for some systems the – for some systems the effects of input do not show up right effects of input do not show up right away, (need prediction displayed to compensate for lag)away, (need prediction displayed to compensate for lag)

Ex: Steering a large ship or turning on hot water in showerEx: Steering a large ship or turning on hot water in shower

Monitoring DisplaysMonitoring Displays Analog Form and DirectionAnalog Form and Direction – scale and direction of – scale and direction of

movement should be consistent with the user’s mental movement should be consistent with the user’s mental modelmodel Requirement for higher numbers at top (or to right) and movement Requirement for higher numbers at top (or to right) and movement

of indicator up (or to right) for high may sometimes conflict (does of indicator up (or to right) for high may sometimes conflict (does scale move or indicator?)scale move or indicator?)

100

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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 Example of Bad Monitoring DisplayDisplay

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).

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.

Principles of Display Principles of Display LayoutLayout

Frequency of UseFrequency of Use – displays used most frequently – displays used most frequently should be placed in the primary visual field (PVA)should be placed in the primary visual field (PVA)

Display RelatednessDisplay Relatedness – related displays should be – related displays should be placed close togetherplaced close together

ConsistencyConsistency – placing displays in a standard position – placing displays in a standard position eases the load on memory and attentioneases the load on memory and attention

Organizational GroupingOrganizational Grouping – displays spatially organized – displays spatially organized to allow for patterns to emerge (pop-out)to allow for patterns to emerge (pop-out)

Stimulus-Response CompatibilityStimulus-Response Compatibility – displays should – displays should be close to their associated controlsbe close to their associated controls

Clutter AvoidanceClutter Avoidance – minimum spacing between – minimum spacing between displaysdisplays

Glass CockpitGlass Cockpit

Space Shuttle’s Glass Cockpit

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

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

Head-Up Displays (HUD)Head-Up Displays (HUD)HUD AdvantagesHUD Advantages Far and near info may be Far and near info may be

monitored in parallelmonitored in parallel Imagery can be mapped onto Imagery can be mapped onto

outside environmentoutside environment No need to frequently re-No need to frequently re-

accommodate eyes when accommodate eyes when switching from displays to switching from displays to outside viewoutside view

Be careful to avoid excess Be careful to avoid excess clutterclutter

HUDs superimpose display information on the PVA

Augmented Reality Augmented Reality DisplaysDisplaysAugmented DisplaysAugmented Displays - display that improves upon reality - display that improves upon reality by superimposing info over actual environmentby superimposing info over actual environment

ex: thermal imaging color codes objects by temperatureex: thermal imaging color codes objects by temperature

Navigation Displays & Navigation Displays & MapsMapsNavigation Displays & Maps:Navigation Displays & Maps: Direct user to destination (path)Direct user to destination (path) Facilitate planningFacilitate planning Help recover from being lostHelp recover from being lost Maintain situation awareness (build mental map)Maintain situation awareness (build mental map)GuidelinesGuidelines Legibility – adequate text sizeLegibility – adequate text size Avoid excessive clutterAvoid excessive clutter ““You are here” personal-referenced view aids lost recoveryYou are here” personal-referenced view aids lost recovery Best if North-up and Nose-up options are availableBest if North-up and Nose-up options are available

Spatial KnowledgeSpatial KnowledgeLevels of Spatial Knowledge*Levels of Spatial Knowledge*1.1. Landmark KnowledgeLandmark Knowledge (egocentric) – learned route by (egocentric) – learned route by

landmarkslandmarks Look for Hardees then turn right past the duck pondLook for Hardees then turn right past the duck pond Requires least mental effort, but useless when lostRequires least mental effort, but useless when lost

2.2. Route KnowledgeRoute Knowledge (egocentric) –route list or commands (egocentric) –route list or commands of how to get from point A to B.of how to get from point A to B. Go 3 miles turn left, 4 miles then turn right, etc.Go 3 miles turn left, 4 miles then turn right, etc.

3.3. Survey KnowledgeSurvey Knowledge (exocentric) – map knowledge, (exocentric) – map knowledge, layout of environmentlayout of environment Well developed mental map allows one to visual spatial relationsWell developed mental map allows one to visual spatial relations Requires most mental effort, but useful when lostRequires most mental effort, but useful when lost

* Move from 1 to 2 to 3 with increased experience

Virtual Reality for Developing Virtual Reality for Developing Spatial KnowledgeSpatial Knowledge

Virtual RealityVirtual Reality – “Fooling people into accepting as real – “Fooling people into accepting as real what is only perceived” what is only perceived” (Karen Carr)(Karen Carr)

Egocentric Navigation (may also provide exocentric)Egocentric Navigation (may also provide exocentric) Immersive (eye view) or tethered (view from outside body)Immersive (eye view) or tethered (view from outside body)

Proprioceptive cuesProprioceptive cues Head-tracking (with HMD)Head-tracking (with HMD)

3-D viewing3-D viewing DynamicDynamic InteractiveInteractive

Virtual Virtual Environments/RealityEnvironments/RealityBenefits/CostsBenefits/Costs

Benefits of VE/VRBenefits of VE/VR TelepresenceTelepresence Hi Fidelity TrainingHi Fidelity Training

Military, medical applicationsMilitary, medical applications On-line ComprehensionOn-line Comprehension

3-D interaction with spaces3-D interaction with spaces Escape from RealityEscape from Reality

Distraction from painDistraction from pain Knowledge ElicitationKnowledge Elicitation

Experts explain as they doExperts explain as they do

Costs of VE/VRCosts of VE/VR CostlyCostly Realistic motion is difficultRealistic motion is difficult Distorted perceptionDistorted perception Limited FOVLimited FOV DisorientationDisorientation CybersicknessCybersickness

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Displays used for TrainingDisplays used for TrainingJoint Combat Advanced Display and Debriefing System (JCADDS)