ABSTRACT
Numerous clinical investigations, designed to test for hemispheric asymmetries in perceptual organization, have used incomplete forms as stimuli. A naming defect is unlikely to occur in patients having a right hemisphere lesion, but the stored representation of the form of objects may be affected, impairing object recognition. A failure to identify an incomplete form may also result from a defect in lower levels of processing such as the organization of elements into perceptual wholes, the computation of a contour from spatially distant elements, or the adequate segmentation of forms into parts. The authors' understanding of the processes underlying poor identification of incomplete forms after brain damage is made difficult for several reasons. The present experiment was designed to test how structural properties can affect the processing of fragmented forms. This result indicates that patient H. J. A, is impaired in the computation of contours from local collinear elements.
