Perception, Cognition and the Perception, Cognition and the VisualVisual

Seeing, thinking, knowing Seeing, thinking, knowing (link to optical video)(link to optical video)

Perception: Pre-attentive Perception: Pre-attentive Perceptual/Cognitive issuesPerceptual/Cognitive issues

– How do human visual systems analyzeHow do human visual systems analyzeimages?images? preattentively,without the need for focused attentionpreattentively,without the need for focused attention Generally less than 200-250 msecs (eyeGenerally less than 200-250 msecs (eye

movements take 200 msecs)movements take 200 msecs)

Preattentive ProcessesPreattentive Processes Grid stays while asterix disappearsGrid stays while asterix disappears

Preattentive ProcessesPreattentive Processes

Cognitive operations prior to focusing attention

Necker Cube 3 WaysNecker Cube 3 Ways

Completing Broken imagesCompleting Broken images

Visual AmbiguityVisual Ambiguity

How Many threes? How Many threes?

12817687561389765469845069856049828212817687561389765469845069856049828267629809858458224509856458945098450967629809858458224509856458945098450980943585909103020990595959577256467580943585909103020990595959577256467505067890456788457898098216776548763605067890456788457898098216776548763649085609129496864908560912949686

How many threes?How many threes?

12817687561128176875613389765469845069856049828289765469845069856049828267629809858458224509856458945098450967629809858458224509856458945098450980948094335585909108590910330209905959595772564675020990595959577256467505067890456788457898098216776548760506789045678845789809821677654876336649085609129496864908560912949686

Response Time: where is the Response Time: where is the horizonatal bar?horizonatal bar?

Where is the letter L?Where is the letter L?

OrientationOrientation

Size/ScaleSize/Scale

Colour (hue)Colour (hue)

Hue: where is the red circle? Hue: where is the red circle? Not Usually Pre-attentiveNot Usually Pre-attentive

Hue & shapeHue & shape

Region SearchRegion Search

Hue boundary identifiedpre-attentively

Form variations do NOTinterfere with hueboundary identification

Form boundary NOTidentified pre-attentively

Hue variations interferewith form boundaryidentification

Area EstimationArea Estimation Blue rectangles? Sloped rectangles?Blue rectangles? Sloped rectangles?

Fill and ShapeFill and Shape

BrightnesssBrightnesss

ShapeShape

Luminance/ContrastLuminance/Contrast

Color for Categories and Color for Categories and SequencesSequences

Links to websites about color systemsLinks to websites about color systems CIECIE, , MunsellMunsell

Using Color--Varied Opnions, Using Color--Varied Opnions, More later in the courseMore later in the course

blue in large regions, not thin linesblue in large regions, not thin lines red and green in the center of thered and green in the center of the

field of view (edges of retina not sensitivefield of view (edges of retina not sensitiveto these)to these)

black, white, yellow in peripheryblack, white, yellow in periphery Color BrewerColor Brewer PantonePantone

Perceptual “Tasks”Perceptual “Tasks”

Target detection ( Is something there?)Target detection ( Is something there?) Boundary detection (Can the elements be Boundary detection (Can the elements be

grouped?)grouped?) Counting ( How many elements of a certain Counting ( How many elements of a certain

type aretype arepresent?)present?)

Perceptual PropertiesPerceptual Properties

Luminance (measured) Brightness (perceived)Luminance (measured) Brightness (perceived) Color Color

– sensory response to electromagnetic radiation-- sensory response to electromagnetic radiation-- wavelengths 0.4-0.7 micrometers)wavelengths 0.4-0.7 micrometers)

– Hue, value, saturationHue, value, saturation TextureTexture ShapeShape Sources: Colin Ware & Morgan Kaufmann Sources: Colin Ware & Morgan Kaufmann

Information Visualization--Perception for DesignInformation Visualization--Perception for Design

Optical Illusions and Optical Illusions and Programmed VariationsProgrammed Variations

LinkLink Chernoff Faces Chernoff Faces linklink

Pre-attentive Perception, Pre-attentive Perception, cognition & visualizationcognition & visualization

“Understanding of what is processed pre-attentivelyis probably the most important contribution that vision

science can make to data visualization.”

BUT“Humans do not perceive much unless we haveat least some expectation and need to see it.”

- Colin Ware

Cognitive issuesCognitive issues

Visualization as a tool useful forVisualization as a tool useful for

aiding comprehension and understandingaiding comprehension and understanding Seeing as thinkingSeeing as thinking Visual Cognition & Attention--Visual CognitionVisual Cognition & Attention--Visual Cognition

Lab. U. Illinois Lab. U. Illinois

Visualizations of Home/House. Child Katrina SurvivorsVisualizations of Home/House. Child Katrina Survivors

Recall: House/Home (Katrina Recall: House/Home (Katrina Victim)Victim)

House/HomeHouse/Home

House as roofHouse as roof

House?HomeHouse?Home

Sources: Slide show of Katrina victim’s drawings of Sources: Slide show of Katrina victim’s drawings of house/home,house/home, Dewann, S. Dewann, S. “Using Crayons to Exorcise Katrina, “Using Crayons to Exorcise Katrina, New York TimesNew York Times, Monday September 17, , Monday September 17, 2007, Arts Section, B1,5.2007, Arts Section, B1,5.

Graphical visualization to Graphical visualization to support more efficient task support more efficient task performanceperformance

– Allowing substitution of rapid perceptualAllowing substitution of rapid perceptual

influences for difficult logical inferencesinfluences for difficult logical inferences– Reducing search for information required for task Reducing search for information required for task

completioncompletion

(Sometimes text is better, however)(Sometimes text is better, however)

IssuesIssues

Cognitive ArtifactsCognitive Artifacts Matching Representation to TaskMatching Representation to Task Representations Aid Info Access and Representations Aid Info Access and

ComputationComputation Naturalness and Experiential CognitionNaturalness and Experiential Cognition

Cognitive MapsCognitive Maps

You have some existing internal model of theYou have some existing internal model of the

system, stops, how to get theresystem, stops, how to get there– glance at SFU map for helpglance at SFU map for help– Refine your internal model, clarifying items and Refine your internal model, clarifying items and

extending itextending it Note differences between your map & the Note differences between your map & the

official oneofficial one

Process Models: Navigation in Process Models: Navigation in Visual systemsVisual systems

-process by which a person looks at a graphic -process by which a person looks at a graphic and makes some use of itand makes some use of it– substepssubsteps– Can you describe process?Can you describe process?– Navigation in visual systems - Creation and Navigation in visual systems - Creation and

interpretation of an internal mental modelinterpretation of an internal mental model

Information foragingInformation foraging

Search for schema (representation)Search for schema (representation) Problem solve to trade off featuresProblem solve to trade off features Search for a new schema that reducesSearch for a new schema that reduces

problemproblem Package the patterns found in somePackage the patterns found in some

output productoutput product

NavigationNavigation

•CrystallizationCrystallization

ProcessProcess

Browsing useful whenBrowsing useful when

Good underlying structure so that items close to oneGood underlying structure so that items close to oneanother can be inferred to be similaranother can be inferred to be similar

Users are unfamiliar with collection contentsUsers are unfamiliar with collection contents Users have limited understanding of how system isUsers have limited understanding of how system is

organized and prefer less cognitively loaded methodorganized and prefer less cognitively loaded methodof explorationof exploration

Users have difficulty verbalizing underlyingUsers have difficulty verbalizing underlyinginformation needinformation need

Information is easier to recognize than describeInformation is easier to recognize than describe