A clear left hemisphere advantage for visuo-spatially based verbal categorization

For a range of tachistoscopically presented stimuli that varied from modified complex Shepard and Metzler figures to simple lines, subjects had to judge whether or not the top or bottom of the stimuli contained the target feature. A marked and consistent right visual field (left hemisphere) advantage was observed for all such tasks. In addition, a task that required subjects to judge whether a solid black rectangle was in front of or behind a white rectangle also yielded a clear left hemisphere advantage. The results are explained in terms of a left hemisphere specialization for spatially based verbal categorizations in general support of Kosslyn's (Psychol. Rev. 94, 148-175, 1984) model.