Feature Level ProcessingLessons from low-level visionApplications in HighlightingIcon (symbol) designGlyph design

Spotfire product

Visual symbols

Architecture for visual thinking

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

Segmentation by Primitive Features

Livingston and HubelNeural 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 ExperimentNumber of irrelevant items variesPre-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 displayMust stand out on some simple dimensioncolor, simple shape = orientation, sizemotion, depth

Lessons for highlighting one of each

Lessons: Highlighting how to make information available to attentionBlinking momentarily attracts attentionA flying box leads attentionUsing colorUsing underliningBlinking momentarily attracts attentionMotion 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, 154-155.

Driver, J., MacLeod, P. and Dienes, Z. (1992) Motion coherence and conjunction search: Implications for guided search theory. Perception and Psychophysics. 51, 1, 79-85.

MEGraph: Experimental systemAllows for various topological range highlighting methodsGoal from 30 to 2000 nodesMEGraph

Pre-Attentive ChannelsForm (orientation/size) ColorSimple motion/blinkingAddition/numerosity (up to 3)Spatial, stereo depth, shading, position

Pre-Attentive ConjunctionsStereo and colorColor and motionColor and positionShape and position

In general: spatial location and some aspect of form

Pre-Attentive LessonsRapid visual search (10 msec/item)Easy to attend toMakes symbols distinctBased on simple visual attributesFaces, etc are not pre-attentive

Designing symbols

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

Spatial ChannelsLike 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 variablesData glyphsPosition (2)Orientation (1)Size (spatial frequency) Motion (2)++Blinking?Color (3)

Note we have the problem of heterogeneity There is no good solutionStar glyphMethod

Starplot glyph

Spotfire product

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

SeparableIntegralMotion Colorred-greenyellow-blueblack-whitered-greenx-size y-sizeColor orientation

Lessons for Information Display

Orthogonality - use a different channel for a different type of informationIf you need this use separable challengeIf you need to highlight by two properties use separable dimensions.

The programmable filterWe can only look for patterns of simple featuresConjunctions of shape, color cannot be programmed for parallel search of fieldConjunctions of depth/motion and color/shape can be

Integral dimensions tend to be seen holistically cannot be separatedSeparable dimensions tend to be seen separately

Searchlight Model of Attention

Searchlight PropertiesSize varies with data densitySize varies with stress levelAttention operators work within the searchlight beamAttention is a tunable filter

Eye movements 3/sec A series of saccades

Low Level: Basic feature analys determines what is seen with minimal effortMid Level: Pattern finding The demands of attention meets automatic processing High Level: Task related visual queries are formed objects/ patterns are pulled into working memory and tested against the query- Need to have the right mappings for queries to be easily satisfied.Attention is focused to execute the query.

Final element is the cost of search.