Hemispheric differences in global versus local processing of hierarchical visual stimuli by normal subjects: new data and a meta-analysis of previous studies.

Twenty-four normal right-handed male subjects classified hierarchical visual stimuli (small letters arranged to form larger letters), which were presented separately to each cerebral hemisphere. Previous studies using similar paradigms have yielded mixed evidence for the specialization of local, analytic processing in the left hemisphere and global, holistic processing in the right hemisphere. No statistically significant evidence for such a pattern of specialization was evident in the results of the present study. However, when meta-analytic techniques were used to combine the present results with those from previous studies, there was evidence that the hypothesized left-hemisphere/local, right-hemisphere/global specialization does in fact exist.