CPSC 599.28/601.28 Cognitive Perspective Sheelagh Carpendale

CPSC 599.28/601.28Cognitive Perspective

Sheelagh Carpendale

Introduction

• Supporting visual thinking– developing representations– comprehension

• some vision perception basics• attention• colour • depth

References

• Colin Ware. (2004) Information Visualization: Perception for Design. Morgan Kaufmann.

• Maureen Stone. (2003) A field guide to digital color. AK Peters• S. S. Stevens. (1961) The Psychophysics of Sensory Function.

Sensory Communication, MIT Press, pp 1-33. • William S. Cleveland, Robert McGill. (1984) Graphical

Perception: Theory, Experimentation and the Application to the Development of Graphical Models. J. Am. Stat. Assoc. 79:387, pp. 531-554.

• Leland Wilkinson. (1993) Comment on Cleveland. Journal of Computational and Graphical Statistics, 2, pp. 355-360.

• Bernice E. Rogowitz and Lloyd A. Treinish. (1996) How Not to Lie with Visualization. Computers In Physics 10(3), pp 268-273. http://www.research.ibm.com/dx/proceedings/pravda/truevis.htm

• C. Brewer. (1999) Color use guidelines for data representation. http://www.personal.psu.edu/faculty/c/a/cab38/ColorSch/ASApaper.html

Foveal vision

• size of a thumbnail at arms length• Corresponds to a small high resolution area on the retina

http://www.cs.nyu.edu/~yap/visual/home/proj/foveation.html

Foveal vision

http://psy.ucsd.edu/~sanstis/SABlur.html

Foveal vision


Field of View• Useful field of view

varies with tasklow character density - as wide as 15o

high character density - as narrow as 1o to 4o

Foveal vision


Saccades

• Fovea gives small high resolution images• Saccades do rapid scanning • Brain assembles • Vision perceived as continuous

http://vision.arc.nasa.gov/personnel/jbm/home/projects/osa98/osa98.html

Eye movements• Saccadic movements

– eye moves rapidly from fixation to fixation– dwell period 200 to 600 msec– saccade takes 20 to 100 msec– peak velocity can be 900 deg/sec– ballistic - cannot be adjusted mid saccade– saccadic suppression - less sensitive visually during a

saccade• smooth-pursuit movements

– ability to ‘lock-on’ to a smoothly moving object– enables head and/or body movements while maintaining

visual contact• convergent movements

– towards - eyes converge – away - eyes diverge

• accommodation– new target - refocus - 200 msec– convergence and accommodation neurologically coupled

Affected by motion

appearance

motion

Field of View

X

Change Blindness • some times changes are not perceived http://viscog.beckman.uiuc.edu/djs_lab/demos.html

http://www.psych.ubc.ca/~rensink/

Rensink, Ronald A.; O'Regan, J. Kevin & Clark, James J. (1997), To see or not to see: the need for attention to perceive changes in scenes, Psychological Science 8 (5): 368-373.

Silverman, M. & Mack, A. (2006), Priming by change blindness: When it does and does not occur, Consciousness and Cognition 15: 409-422.

Simons, Daniel J. & Levin, Daniel T. (1998), Failure to detect changes to people during a real-world interaction, Psychonomic Bulletin and Review 5: 644-649.

Light and Objects

• objects reflect light• luminance

• black paper in sunlight vs. white paper in indoor lighting conditions

• eyes and photometers - we see differences not absolutes (this is similar to many sensory systems)

Image from John MCannImage from John MCann (slide M. Stone)Image from John MCann (slide M. Stone)

Image from John MCannImage from John MCann

Image from John MCann (slide M. Stone)Image from John MCann (slide M. Stone)

Image from John MCann (slide M. Stone)Image from John MCann (slide M. Stone)

Human Perception and Light• Difference Signaling

• Contrast vs. value information• Light value information vs. object information.

• cell has normal rate• light in centre excites • light in surrounds inhibits

Consequences

• Hermann Grid Illusion

Consequences

• Scintillating Grid

Consequences

• Grating Induction Effect

Consequences

• Mach Banding

Consequences

• Chevreul Illusion

Consequences

• Crispening

Consequences

• Craik-Cornsweet Effect

Seurat: The Bathers

• Craik-Cornsweet Effect

Lightness/Brightness summary• Encoding of Information in greyscale

• Perception may not be as expected• C. Ware’s advice - often better ways to encode

information than to use a greyscale• The human eye is not a photometer, and

should not be treated as such• Understanding how the eye does work can

help us avoid problems that might arise

Overview for Attention

• eye movements• searching• neural processing• information density• information coding• applications

Reading and short term memory• How many symbols can you remember?

• Usually about 7• 7+ or - 2• short term

memory

as 1o

X?

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Pre-attentive processing

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X

Number of distracters

Response time(milliseconds)

1000

250

750

500

9 1263

X X X

typical results

pre-attentivenon-pre-attentive

X

Pre-attentive processing• Features thought to be pre-attentive

• form– line orientation– line length– line width– line collinearity– size– curvature– spatial grouping– added marks– numerosity

• colour– hue– intensity

• spatial position– 2d position– stereoscopic depth– convex/concave from shading

• motion– flicker– direction of motion


orientation

numbersize

shapecurved/straight

shape


value

Parallelism ??Juncture ??

convex/concave

enclosure

addition

Pre-attentive processing• Colour

Colour

shape

Pre-attentive processing• Conjunction search• Colour and shape


• generalizations • which dominates seems to vary with degree of

‘separation’ • adding is ‘better’ than taking away• to be pre-attentive a colour needs to be ‘outside’ the

boundary of the region defined by the other colours in the display

Position: best for all data typesdata type

Mackinlay, Automating the Design of Graphical Presentations of Relational Information, ACM TOG 5:2, 1986

For quantitative data

• Graphical Perception: Theory, Experimentation and the Application to the Development of Graphical Models. William S. Cleveland, Robert McGill, J. Am. Stat. Assoc. 79:387, pp. 531-554, 1984.

Frames can increase accuracy

AA TD

AA TD

Similar to Ware’s adaptation of Nakayama et al.

• Based on visual gestalt (perception of ‘wholeness’)

• Descriptive rather than explanatory

ProximitySimilarity Continuity (connectedness)ClosureFigure/groundSymmetryCommon fate (things moving together)

Gestalt Principles: perception


Proximity


xa

b

Information Visualization: Perception for Design.

Ware, Morgan Kaufmann, 2000


Proximity Similarity


Continuity

Gestalt Principles



• connectedness

Gestalt Principles



• Closure

Gestalt Principles

• Closure • Overrules

proximity, similarity

Gestalt Principles



• Symmetry • Emphasizes relationships

Gestalt Principles



• Common fate • http://tepserver.ucsd.edu/~jlevin/gp/time-example-

common-fate/

Gestalt Principles



Figure/ground

Smaller components seen as objects

Gestalt Principles

figure/ground

Gestalt Principles

M. C. Escher print: Study of the Regular Division of the Plane with Horsemen

Visual variable

Dimensionality

comment

Spatial position x, y, z

colour 3D – colour theory Luminance contrast needed

shape 2-3? unknown Size and degree of elongation and ?

orientation 3D – orientation of axes

not independent of shape

Surface texture 3D Not independent of shape and colour

Motion 2-3? Largely unknown

blink 1D Not independent of motion

•Depth Cue Theory-Monocular Static (Pictorial)-Monocular Dynamic (Moving

Picture)-Binocular

•Task-Based Space Perception

Space Perception

Monocular Static (Pictorial)

-Linear Perspective-Texture Gradient-Size Gradient-Occlusion -Depth of Focus-Cast Shadows-Shape-from-Shading

Space Perception: depth cue theory

The Geometry of Linear Perspective

Texture Gradient

Convergent Lines & Size Gradient

Occlusion

Depth of Focus

Cast Shadows

Monocular Dynamic (Moving Picture)

-Structure from Motion (motion parallax, kinetic depth)

a) Velocity Gradient, b) Velocity Field, c) Kinetic Depth

Binocular• Eye convergence

• Stereoscopic Depth

• Problems with Stereoscopic Displays

• Making Effective Stereoscopic Displays

Vergence Angle

Simple Stereo Display

Frame Cancellation

Geometry of Virtual Eye Separation

Artificial Spatial Cues

Dropping Lines to Ground Plane

Artificial Spatial Cues

Proximity Luminance Covariance or Depth Cueing

Depth Cues in Combination

Vergence Kinetic

depth

Depth of focus

Shadows

Shading

Occlusion

Linear perspective

Texture gradients

Stereo

Task-Based Space Perception

• Tracing Data Paths in 3D Graphs

• Judging the Morphology of Surfaces and Target Detection

• Patterns of Points in 3D Space

• Judging Relative Positions of Objects in Space

• Judging the Relative Movement of Self within the Environment

• Judging the “Up” Direction

• The Esthetic Impression of 3D Space (Presence)

Is there more space in 3D?

•1D has how much data display space?

•2D has how much data display space?

•3D?

Stereo 1.6Stereo 1.6

Motion 2.2Motion 2.2

Stereo and motion 3.0Stereo and motion 3.0

http://www.illusionworks.com/

http://www.psychology.psych.ndsu.nodak.edu/mccourt/website/htdocs/HomePage/

Projects/Brightness/Brightness%20Perception.htm

http://psy.ucsd.edu/~sanstis/SASlides.html

Documents

CPSC 599.28/601.28 Cognitive Perspective Sheelagh Carpendale