Hemispheric specialization for local and global processing of hierarchical visual stimuli in chimpanzees (Pan troglodytes).

This study examined laterality in global and local processing of hierarchical compound stimuli in seven chimpanzees (Pan troglodytes). A divided visual half-field paradigm was used that allowed for unilateral presentation of compound stimuli to either the left or right hemisphere. Comparison stimuli differing on the basis of their global configuration, local elements or both features followed sample stimulus presentation. Subjects were required to accurately discriminate the comparison stimuli on the basis of these features relative to the sample stimulus. No laterality effects were found for accuracy; however, for reaction time, a significant interaction was found between visual field and processing mode. An overall right visual field advantage was found for local processing but no visual field differences for global processing. The overall results are consistent with previous findings in humans and suggests homologous lateralization in chimpanzees and humans.