Spatial attention in the mental architecture: Evidence from neuropsychology

Abstract

Using neuropsychological evidence, this paper examines whether spatial attention functions as a domain-specific module or as a more general-purpose central processor. Data are presented from two spatial attention cuing tasks completed by subjects, with an acquired attentional deficit, and control subjects. In both tasks, an arrow indicated with high probability the side of response (response task) or the side of space on which the stimulus would appear (visuospatial task). In the response task, the stimuli appeared foveally and the response component was lateralized, and in the visuospatial task, the stimuli were lateralized and the response component remained constant in the midline. Only the neglect subjects showed a disproportionate increase in reaction time on both the response and visuospatial tasks when the arrow cued the subject to the ipsilateral side and the stimulus or response was on the side of space contralateral to the lesion. The substantial association across the two tasks suggests that a common underlying internal spatial representation subserves perception and action. While this finding is consistent with Fodor's view of a cross-domain processor, it does not meet all of his criteria of a central processor. We conclude, therefore, that the posterior attentional mechanism is strictly neither a module nor a central processor. Rather, these results suggest that a common attentional mechanism may subserve behavior in domains that are tightly coupled.

This research was supported by grants from the Medical Research Council of Canada to MB and SEB (MA 11739) and by a Medical Research Council of Canada Fellowship to MB. This research was conducted while the first author was at the Rotman Research Institute of Baycrest Centre in Toronto. The work was presented at the Institute for Advanced Studies meeting on Modularity in Jerusalem in May, 1993 and the authors are grateful to the Institute for their support. We thank Jane Collins for her help with data collection and statistical analysis, and David Plaut, Eduardo Bisiach, Yonatan Goshen-Gottstein, Marcie Wallace, and Terri Huston for their useful comments.