Perception, Cognition and the Visual Seeing, thinking, knowing (link to optical video) (link to optical video) (link to optical video)

Perception: Pre-attentive Perceptual/Cognitive issues –How do human visual systems analyze images? preattentively,without the need for focused attention preattentively,without the need for focused attention Generally less than msecs (eye movements take 200 msecs) Generally less than msecs (eye movements take 200 msecs)

Preattentive Processes Grid stays while asterix disappears Grid stays while asterix disappears

Preattentive Processes Cognitive operations prior to focusing attention

Necker Cube 3 Ways

Completing Broken images

Visual Ambiguity

How Many threes?

How many threes?

Response Time: where is the horizonatal bar?

Where is the letter L?

Orientation

Size/Scale

Colour (hue)

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

Hue & shape

Region Search Hue boundary identified pre-attentively Form variations do NOT interfere with hue boundary identification Form boundary NOT identified pre-attentively Hue variations interfere with form boundary identification

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

Fill and Shape

Brightnesss

Shape

Luminance/Contrast

Color for Categories and Sequences Links to websites about color systems Links to websites about color systems CIE, Munsell CIE, Munsell CIEMunsell CIEMunsell

Using Color--Varied Opnions, More later in the course blue in large regions, not thin lines blue in large regions, not thin lines red and green in the center of the field of view (edges of retina not sensitive to these) red and green in the center of the field of view (edges of retina not sensitive to these) black, white, yellow in periphery black, white, yellow in periphery Color Brewer Color Brewer Color Brewer Color Brewer Pantone Pantone Pantone

Perceptual “Tasks” Target detection ( Is something there?) Target detection ( Is something there?) Boundary detection (Can the elements be grouped?) Boundary detection (Can the elements be grouped?) Counting ( How many elements of a certain type are present?) Counting ( How many elements of a certain type are present?)

Perceptual Properties Luminance (measured) Brightness (perceived) Luminance (measured) Brightness (perceived) Color Color –sensory response to electromagnetic radiation-- wavelengths micrometers) –Hue, value, saturation Texture Texture Shape Shape Sources: Colin Ware & Morgan Kaufmann Information Visualization--Perception for Design Sources: Colin Ware & Morgan Kaufmann Information Visualization--Perception for Design

Optical Illusions and Programmed Variations Link Link Link Chernoff Faces link Chernoff Faces linklink

Pre-attentive Perception, cognition & visualization “Understanding of what is processed pre-attentively is probably the most important contribution that vision science can make to data visualization.” BUT “Humans do not perceive much unless we have at least some expectation and need to see it.” - Colin Ware

Cognitive issues Visualization as a tool useful for Visualization as a tool useful for aiding comprehension and understanding Seeing as thinking Seeing as thinking Visual Cognition & Attention--Visual Cognition Lab. U. Illinois Visual Cognition & Attention--Visual Cognition Lab. U. Illinois Visual Cognition & Attention--Visual Cognition Lab. U. Illinois Visual Cognition & Attention--Visual Cognition Lab. U. Illinois

Visualizations of Home/House. Child Katrina Survivors

Recall: House/Home (Katrina Victim)

House/Home House as roof House as roof

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

Graphical visualization to support more efficient task performance – Allowing substitution of rapid perceptual influences for difficult logical inferences –Reducing search for information required for task completion (Sometimes text is better, however)

Issues Cognitive Artifacts Cognitive Artifacts Matching Representation to Task Matching Representation to Task Representations Aid Info Access and Computation Representations Aid Info Access and Computation Naturalness and Experiential Cognition Naturalness and Experiential Cognition

Cognitive Maps You have some existing internal model of the You have some existing internal model of the system, stops, how to get there –glance at SFU map for help –Refine your internal model, clarifying items and extending it Note differences between your map & the official one Note differences between your map & the official one

Process Models: Navigation in Visual systems -process by which a person looks at a graphic and makes some use of it –substeps –Can you describe process? –Navigation in visual systems - Creation and interpretation of an internal mental model

Information foraging Search for schema (representation) Search for schema (representation) Problem solve to trade off features Problem solve to trade off features Search for a new schema that reduces problem Search for a new schema that reduces problem Package the patterns found in some output product Package the patterns found in some output product

Navigation

CrystallizationCrystallization

Process

Browsing useful when Good underlying structure so that items close to one another can be inferred to be similar Good underlying structure so that items close to one another can be inferred to be similar Users are unfamiliar with collection contents Users are unfamiliar with collection contents Users have limited understanding of how system is organized and prefer less cognitively loaded method of exploration Users have limited understanding of how system is organized and prefer less cognitively loaded method of exploration Users have difficulty verbalizing underlying information need Users have difficulty verbalizing underlying information need Information is easier to recognize than describe Information is easier to recognize than describe