Parallel search for a conjunction of contrast polarity and shape.
When a target object embedded in an array of other objects can be distinguished along a single feature dimension (e.g. color or shape), it can be detected in parallel. When a target object is defined by a conjunction of stimulus features, at least some serial search is required, indicating that the visual system is less efficient in conducting a parallel search over two stimulus dimensions simultaneously. Some exceptions to this finding have been reported. The present results suggest another exception: search for a conjunction of contrast polarity and shape can be conducted in parallel while the same conjunction consisting of color and shape requires some serial search. The neurophysiological implications are discussed.
TNO Human Factors Research Institute, Soesterberg, The Netherlands.
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J
Theeuwes
F L
FL
Kooi
D003118:Color Perception / Q000502:physiology; D003196:Computer Graphics; D006801:Humans; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011601:Psychophysics; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors