Right temporal-lobe contribution to global visual processing

The performance of 92 patients with unilateral temporal- or frontal-lobe excisions and 35 normal control subjects was tested under two experimental conditions (global, local) of a Stroop-type reaction-time task, employing either hierarchically structured letters or abstract designs as stimuli. In the local condition, subjects were asked to focus their attention on the small forms and to ignore the large form, whereas they were instructed to do the reverse in the global condition. The results showed that, in the local condition, the patients with right temporal-lobe lesions were less affected than the other groups by interference from the global aspect of the stimulus. This reduced sensitivity to the overall configuration of the stimulus was unrelated to the extent of hippocampal removal or to the presence of visual-field defects. These findings support the hypothesis that the human right temporal neocortex contributes to the global processing of visual information.