Stimulus configuration in selective attention tasks

1. Stimulus configuration in selective attention tasks Pomerantz, J. R. & Garner, W. R. (1973). Perception & Psychophysics, 14, 565-569.

2. Gestalt • Two or more elements appear to form a unitary configuration, or may appear simply as a collection of separate elements. • The rules of Gestalt based mostly on the principles of proximity and similarity.

3. Present study • The problem of configuration is viewed within the context of information processing, specifically as a problem related to perceptual independence. • That is…if elements are organized into a larger unit, then selective attention to individual elements in the configuration should not be possible.

4. Present study • To use an information processing approach, … • Each stimulus was considered as one of a set of stimuli. • The stimulus was defined dimensionally • Two stimulus dimensions each with two levels • Two dimensions: left and right • Two levels: left and right curvature of a parenthesis ( ) • Primary process of concern: selective attention

5. Experiment • Three differentiate conditions allow the independence of stimulus dimensions to be evaluated:discriminate between stimuli • One discrimination control condition • Two discrimination correlated condition • Two discrimination correlated condition one correlated orthogonal LL LR ( ( ( ) -----v.s.----- . )( ) ) RL RR LL RL ( ( )( -----v.s.----- .( ) ) ) LR RR L L ( ( --v.s.-- .) ( R L L R ( ) --v.s.-- ) ) R R L L ( ( --v.s.-- ( ) L R R L ) ( --v.s.-- .) ) R R L L ( ( --v.s.-- .) ) R R L R ( ) --v.s.-- .) ( R L

6. Purpose • To investigate the role of selective attention in the context of three different experimental operations

7. Prediction • All three tasks yield equivalent performance • Attention was paid only to the relevant dimension in each task. • It took subjects more time to complete the orthogonal task than the control task and less time for correlated task • Selective attention was not possible, since subjects would attend to a single dimension and ignored irrelevant interfering information • The correlated task was complete with information integration • Interference and facilitation: dimensional integralitynone: dimensional separability • Interference occurred with the orthogonal task, but no facilitation with the correlated task • Dimensions were not treated as dimensions, but rather served to generate nominally related stimuli • grouping

8. Procedure • Classified a deck of cards into two piles • Sort as fast as possible, but without making errors • 8 deck each sort, 32 cards each deck • 1 practice sort and 8 experiment sort (1 per condition) • The order of condition was counterbalanced one correlated orthogonal LL LR ( ( ( ) -----v.s.----- . )( ) ) RL RR LL RL ( ( )( -----v.s.----- .( ) ) ) LR RR L L ( ( --v.s.-- .) ( R L L R ( ) --v.s.-- ) ) R R L L ( ( --v.s.-- ( ) L R R L ) ( --v.s.-- .) ) R R L L ( ( --v.s.-- .) ) R R L R ( ) --v.s.-- .) ( R L

9. Results

10. Results • Subjects were not able to attend selectively to one element of these stimuli while ignoring, or filtering, the other. • It was no easier to classify stimuli when both dimensions varied in a completely correlated manner than when only one dimension varied. • These dimension do not serve that function for subjects. • These shapes may be treated nominally, or categorically, in perceptual process.

11. Result • No interference effect when using this kind of stimuli

12. Discussion • Pattern goodness may be involved in the discrimination process • Good patterns were discriminated and encoded more quickly than poor ones • The goodness of pattern from best to worst in this study is LR, RL, LL, and RR

13. Discussion • LR> RL> LL> RR ( ) ) ( ( ( ) ) • Predictions can be made for the relative difficulty of the various two-stimulus discriminations in the main experiment

14. Discussion • Physically separate stimulus elements may be treated perceptually as belonging to a single configuration • Configuration does not always result