Hemisphere specialization: Definitions, not incantations

Visuospatial dysfunction following unilateral brain damage: dissociations in hierarchical and hemispatial analysis

Unlike the aphasias, visuospatial dysfunction has resisted fractionation into meaningful spared and impaired component functions. In this study, we show that unilateral brain damage results in pronounced dissociations in both hierarchical and hemispatial processing. Patients with left-hemisphere damage showed the greatest impairment in drawing forms at the lower level of hierarchical stimuli presented in right hemispace, whereas patients with right-hemisphere compromise displayed the opposite pattern. We discuss implications of these results for research in visuospatial function and clinical assessment of visuospatial dysfunction.

Hemispheric specialization of memory for visual hierarchical stimuli

Unilateral brain-damaged patients and normal control subjects were asked to remember visual hierarchical stimuli consisting of larger forms constructed from smaller forms. The right-hemisphere damaged patients made more errors in remembering the larger forms relative to the smaller forms, whereas the left-hemisphere damaged patients made more errors in remembering the smaller forms relative to the larger forms. These findings are discussed as they relate to hemispheric specialization for visuospatial processing.