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A search asymmetry reversed by figure-ground assignment.
1Cognitive Science Research Centre, School of Psychology, University of Birmingham, B15 2TT, United Kingdom. g.w.humphreys@bham.ac.uk
Psychological Science
|March 29, 2001
Summary
Visual search asymmetry between concave and convex shapes can be reversed by changing how edges are perceived. This demonstrates that figure-ground assignment influences visual attention and search efficiency.
Area of Science:
- Cognitive Psychology
- Visual Perception
- Neuroscience
Background:
- A known visual search asymmetry favors concave targets over convex ones.
- This asymmetry suggests differences in how the visual system processes concave versus convex shapes.
Purpose of the Study:
- To investigate if figure-ground assignment can reverse the concave-convex search asymmetry.
- To explore the role of top-down processes in modulating visual search efficiency.
Main Methods:
- Utilized shapes with ambiguous local figure-ground relations.
- Manipulated edge assignment to concave or convex 'figures' to alter perception.
- Measured visual search efficiency using search slopes (ms/item).
Main Results:
- The same stimuli yielded efficient (approx. 10 ms/item) or inefficient (approx. 30-40 ms/item) search slopes.
- Search efficiency depended on whether edges were assigned to concave or convex figures.
- This assignment process was shown to be modulated by top-down, task-set influences.
Conclusions:
- Figure-ground assignment is a critical factor that can reverse established visual search asymmetries.
- Attention allocation follows figure-ground computation, which can be influenced by top-down control.
- The findings provide insights into the dynamic interplay between perception and attention in visual search.