ATTENTION TO WITHIN-OBJECT AND BETWEEN-OBJECT SPATIAL REPRESENTATIONS- MULTIPLE SITES FOR VISUAL SELECTION

Our ability both to recognise visually presented objects and to intera ct with them appropriately depends upon detailed interaction between v isual attentional and visual recognition systems. We report data from two neuropsychological cases indicating that the allocation of attenti on in vision is determined by at least two forms of spatial representa tion (within-object and between-object spatial coding). In both cases there was unilateral neglect of one side of visual displays if items i n the displays were coded as parts of a single perceptual object, and neglect of the opposite side if items were coded as separate perceptua l objects. In addition, attentional cueing effects to either the left or right side were specific to the form of representation involved. Th ese cases demonstrate that there is parallel coding of visual displays into within- and between-object spatial representations. Further, vis ual selection operates independently on the two forms of visual repres entation. The data support an argument for the existence of multiple s ites of selection in vision.