Hemispheric specialization for categorical and coordinate spatial representations: A reappraisal

Abstract

The purpose of the present study was to examine Kosslyn's (1987) claim that the left hemisphere (LH) is specialized for the computation of categorical spatial representations and that the right hemisphere (RH) is specialized for the computation of coordinate spatial representations. Categorical representations involve making judgments about the relative position ofthe components of a visual stimulus (e.g., whether one component is abovelbelow another). Coordinate representations involve calibrating absolute distances between the components of a visual stimulus (e.g., whether one component is within 5 mm of another). Thirty-two male and 32 female undergraduates were administered two versions of a categorical or a coordinate task over three blocks of 36 trials. Within each block, items were presented to the right visual field-left hemisphere (RVF-LH), the left visual field-right hemisphere (LVF-RH), or a centralized position. Overall, results were more supportive of Kosslyn's assertions concerning the role played by the RH in the computation of spatial representations. Specifically, subjects displayed an LVF-RH advantage when performing both versions ofthe coordinate task. The LVF-RH advantage on the coordinate task, however, was confined to the first block of trials. Finally, it was found that males were more likely than females to display faster reaction times (RTs) on coordinate tasks, slower RTs on categorical tasks, and an LVF-RH advantage in computing coordinate tasks. Kosslyn (1987) proposed that the human visual system computes two types of spatial representations, and that the processing subsystems responsible for the computation of these distinct representations are lateralized to different cerebral hemispheres. One purpose of the present study was to examine the generalizability of this claim by using two versions of a visual-spatial processing task. A second purpose was to examine individual differencesparticularly sex differences-in the computation of different types of spatial representation. Kosslyn argued that the left hemisphere (LH), because of the important role that it plays in language functioning, becomes specialized for computing categorical spatial representations. Categorical spatial representations involve the determination of whether the components of a multipart, nonrigid visual stimulus share a generalized, abstract relationship with each other (e.g., whether one component is "outside of," "on top of," or "attached to" another component). Kosslyn also maintained that the right hemisphere (RH), beThis researchwassupportedin part by NIAResearch Grant AG06041 to W. 1. Hoyer. We wish to acknowledge theassistance ofScottl0hns0n in task development, Mehmet Yavuzer in programming, and Carl Crockett

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Picture the difference: electrophysiological investigations of picture processing in the two cerebral hemispheres

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Differential impact of posterior lesions in the left and right hemisphere on visual category learning and generalization to contrast reversal

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