Neglect in vision and visual imagery: a double dissociation.

We report two patients with right hemisphere lesions who demonstrate a double dissociation on visual imagery and visual perceptual tasks. One (M.N.) performed normally on a variety of standard tests for neglects as well as on measures of visual attention known to be sensitive to the presence of neglect, yet failed to report items from the left side of an imagined scene. In contrast, the other (C.I.) performed normally on tests of visual imagery but demonstrated substantial neglect on visual perceptual and visual attentional tasks. These data are not readily accommodated by accounts which attribute neglect to a single processing deficit, but suggest that the disorder is a heterogeneous syndrome attributable to disruptions of different aspects of spatial cognition.