Cognitive neuropsychological research on inter- and intra-hemispheric interference

The main aim of the present research was to investigate interhemispheric interaction in local and global processing. A pair of a single letter and a Navon-type hierarchical pattern was presented to a unilateral (Within-Field) and a bilateral visual-fields (Across-Field). In the first series of experiments, which used a small-single letter as a target, the local interhemispheric interference in Across-Field was larger when the target was presented to the right hemisphere (RH) than when it was presented to the left hemisphere. In the second series of experiments, which used a large-single letter as a target, only a global interference appeared and its size was constant irrespective of the side where the distracter was presented. These findings suggested that interhemispheric interaction would be modulated by attentional allocation.The second aim of the current study was to examine the effect of interference on interhemispheric interaction in the reverse-stroop task. In two experiments, color-word in black ink and color-patch in red or blue ink were briefly presented to a bilateral visual-field (BVF). The participants were asked to identify the color word, ignoring the color patch. In Experiment 1, color-words written in kanji character were used as target ("赤" or "青"). In Experiment 2, color-words written in kana character were used as target ("あか" or "あお"). The result in first experiment showed that the size of the interference effect was invariant irrespective of the visual-field of the target. On the contrary, in the second experiment, the interference effect was larger in the condition where the kana color-word was presented to LVF than to RVF. These result suggested that the interference effect would be modulated by the dominant hemisphere for processing the target.

The main aim of the present research was to investigate interhemispheric interaction in local and global processing. A pair of a single letter and a Navon-type hierarchical pattern was presented to a unilateral (Within-Field) and a bilateral visual-fields (Across-Field). In the first series of experiments, which used a small-single letter as a target, the local interhemispheric interference in Across-Field was larger when the target was presented to the right hemisphere (RH) than when it was presented to the left hemisphere. In the second series of experiments, which used a large-single letter as a target, only a global interference appeared and its size was constant irrespective of the side where the distracter was presented. These findings suggested that interhemispheric interaction would be modulated by attentional allocation.The second aim of the current study was to examine the effect of interference on interhemispheric interaction in the reverse-stroop task. In two experiments, color-word in black ink and color-patch in red or blue ink were briefly presented to a bilateral visual-field (BVF). The participants were asked to identify the color word, ignoring the color patch. In Experiment 1, color-words written in kanji character were used as target ("赤" or "青"). In Experiment 2, color-words written in kana character were used as target ("あか" or "あお"). The result in first experiment showed that the size of the interference effect was invariant irrespective of the visual-field of the target. On the contrary, in the second experiment, the interference effect was larger in the condition where the kana color-word was presented to LVF than to RVF. These result suggested that the interference effect would be modulated by the dominant hemisphere for processing the target.