[The effects of global and local processing on intra- and inter-hemispheric interaction].

Our study investigated intra- and inter-hemispheric interference in local and global processing. A pair of single letter and a Navon-type hierarchical pattern was presented to a unilateral (Within-Field) or bilateral visual field (Across-Field), where one letter was the target and a Navon-type hierarchical pattern as a distracter. In Experiment 1, where a small letter was the target, the local interference was larger when the distracter was presented to the left hemisphere (LH) than when it was presented to the right hemisphere (RH), for both presentation modes (Within- and Across Field). The size of the global interference was constant irrespective of the side where the distracter was presented, for both presentation modes. In Experiment 2, which used a large-single letter as a target, only a global interference was found and the size of the effect was larger when the distracter was presented to the RH than the LH in the Within-Field condition. These findings suggested that intra- and inter-hemispheric interactions are modulated by global and local processing.