Spatially parallel processing of within-dimension conjunctions.
Within-dimension conjunction search for red-green targets amongst red-blue, and blue-green, nontargets is extremely inefficient (Wolfe et al, 1990 Journal of Experimental Psychology: Human Perception and Performance 16 879-892). We tested whether pairs of red-green conjunction targets can nevertheless be processed spatially in parallel. Participants made speeded detection responses whenever a red-green target was present. Across trials where a second identical target was present, the distribution of detection times was compatible with the assumption that targets were processed in parallel (Miller, 1982 Cognitive Psychology 14 247-279). We show that this was not an artifact of response-competition or feature-based processing. We suggest that within-dimension conjunctions can be processed spatially in parallel. Visual search for such items may be inefficient owing to within-dimension grouping between items.
School of Psychology, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. k.j.linnell@bham.ac.uk
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Linnell
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Humphreys
D000328:Adult; D003118:Color Perception / Q000502:physiology*; D005260:Female; D005556:Form Perception / Q000502:physiology*; D006801:Humans; D008297:Male; D011601:Psychophysics