Feature Level Processing Lessons from low-level vision Applications in Highlighting Icon (symbol) design Glyph design

Spotfire product

Visual symbols

Architecture for visual thinking

Primitives of Perception (the phonemes). The whole visual field is processed in parallel This machinery tells us what kinds of information are easily distinguished Popout effects (general attention) Segmentation effects (dividing up the visual field)

Segmentation by Primitive Features

Livingston and Hubel Neural Architecture

Orientation and Size (Gabor primitives)

Image segmentation based on texture

Vector fields like using gabors

Pre-Attentive Processing

Color is Pre-Attentive (Pops out)

Generic Pre-Attentive Experiment Number of irrelevant items varies Pre-attentive 10 msec per item or better.

Color

Orientation

Motion

Size

Simple shading

Conjunction (does not pop out)

Semantic Depth of Field

Compound features (do not pop out)

Surrounded colors do not pop out

Laws of pre attentive display Must stand out on some simple dimension color, simple shape = orientation, size motion, depth Lessons for highlighting – one of each

Blinking momentarily attracts attention Lessons: Highlighting how to make information available to attention A flying box leads attention Using color Using underlining Blinking momentarily attracts attention Motion elicits an orienting response

More Pre-Attentive

Conjunction (does not pop out)

Pre-attentive conjunction

Conjunctions of motion and shape do pop out. (color also?) McLeod, P., Driver, J. and Crisp, J. (1988) Visual search for a conjunction of movement and form is parallel. Nature 332, Driver, J., MacLeod, P. and Dienes, Z. (1992) Motion coherence and conjunction search: Implications for guided search theory. Perception and Psychophysics. 51, 1,

MEGraph: Experimental system Allows for various topological range highlighting methods Goal from 30 to 2000 nodes MEGraph

Pre-Attentive Channels Form (orientation/size) Color Simple motion/blinking Addition/numerosity (up to 3) Spatial, stereo depth, shading, position

Pre-Attentive Conjunctions Stereo and color Color and motion Color and position Shape and position In general: spatial location and some aspect of form

Pre-Attentive Lessons Rapid visual search (10 msec/item) Easy to attend to Makes symbols distinct Based on simple visual attributes Faces, etc are not pre-attentive

Designing symbols

Perceptual Channels Color (3) Shape (size, orient) Motion (2?) Texture (2++) Position (x,y)

Spatial Channels Like interferes with like

Size contrast effect

Orient contrast

Size contrast effects can cause errors in information display

Chris Weigle: orientation channels for info display

Mapping data to display variables Data glyphs Position (2) Orientation (1) Size (spatial frequency) Motion (2)++ Blinking? Color (3) Note we have the problem of heterogeneity – There is no good solution Star glyph Method

Starplot glyph

Spotfire product

Integral and Separable dimension (Garner) Can we read display attributes Independently Holistically Speeded classification task. Sort into two piles on one dimension or another

Separable Integral Motion Color red-greenyellow-blue black-whitered-green x-size y-size Color orientation

Lessons for Information Display Orthogonality - use a different channel for a different type of information If you need this use separable challenge If you need to highlight by two properties use separable dimensions.

The programmable filter We can only look for patterns of simple features Conjunctions of shape, color cannot be programmed for parallel search of field Conjunctions of depth/motion and color/shape can be Integral dimensions tend to be seen holistically cannot be separated Separable dimensions tend to be seen separately

Searchlight Model of Attention

Searchlight Properties Size varies with data density Size varies with stress level Attention operators work within the searchlight beam Attention is a tunable filter Eye movements 3/sec – A series of saccades