Abstract
We present neuropsychological evidence distinguishing binding between form and color (cross-domain binding) and binding between form elements (within-domain binding). We contrasted conjunctive search requiring feature binding, from difficult feature search, using control participants and patients with unilateral parietal or fronto/temporal lesions. The standard advantage for feature over conjunction search was reversed, to rule out effects of task difficulty or loss of top-down guidance of search, that could differentially affect conjunction targets. Despite this, parietal patients found search for color-form conjunctions harder than difficult feature search, when targets fell contralateral to their lesion. Controls and frontal/fronto-temporal patients, however, always found the feature search task more difficult. In contrast, the parietal patients showed the same pattern as the other participants with form conjunctions, with form conjunctions advantaged relative to feature search. These data indicate a qualitative difference between binding in the form domain and binding across form and color, consistent with theories that propose distinct binding processes in vision.
Medical Research Council (UK)