Visual and spatial mental imagery: Dissociable systems of representation

Abstract

We argue that the debate over whether mental images are visual or spatial representations is based on the false premise that they must be one or the other. In support of the hypothesis that mental imagery has distinct visual and spatial components of representation, we (1) point out a correspondence between the notions of visual appearance and spatial location representations in visual neurophysiology, on the one hand, and the notions of visual and spatial representations as used in the debate about mental imagery, on the other; and (2) present the performance of a brain-damaged patient with impaired visual appearance representations on a variety of tasks used by cognitive psychologists on one side or other of the visual vs spatial imagery debate. The patient is severely impaired on tasks previously used to argue for the visual nature of imagery, but performs normally on tasks previously used to argue for the spatial nature of imagery. This implies that the two groups of tasks tap distinct types of representation, which are neurologically dissociable and hence comprise functionally independent subsystems of imagery representation.