OBJECT-BASED FACILITATION AND INHIBITION FROM VISUAL ORIENTING IN THEHUMAN SPLIT-BRAIN

Object-based attention was examined in 2 split-brain patients. A precu ed object could move within a visual field or cross the midline to the opposite field. Normal individuals show an inhibition in detecting si gnals in the cued object whether it moves within or between fields. Bo th patients showed this effect when the cued object moved within a vis ual field. When it crossed the midline into the opposite visual field, however, detection was faster in the cued box. These results reveal b oth facilitatory and inhibitory effects on attention that are object b ased and may last for several hundred milliseconds. However, the inhib ition requires an intact corpus callosum for interhemispheric transfer , whereas the facilitation is transferred subcortically.