Abstract
We perceive a stable world despite frequent shifts in eye position and attentional focus. These shifts often cause objects to be translated from one visual field to another. However, it is unclear how such translational shifts in eye position or attention affect which cerebral hemisphere will represent objects of interest. Are the items immediately remapped to the new hemisphere following the shift, or do they continue to linger in the initial encoding hemisphere? Here, we examined hemispheric remapping following either a change in eye position or attentional focus. We recorded a sustained working memory component (Contralateral Delay Activity; CDA) of the event related potential while subjects performed a change detection task in which the items remained continuously visible. Subjects began all trials by fixating a central cross prior to the presentation of the memory array. In the eye movement block, subjects either maintained central fixation throughout the entire trial, or they were cued to refixate a new position that was 7 degrees to the left or right of central fixation during the middle of the retention period (bringing the objects into a new visual field). In the attention movement block, subjects maintained central fixation and either attended to an initially cued set of items in one hemifield throughout the entire trial, or were cued to shift their attention to the items in the opposite visual hemifield during the middle of the retention period. The results from the eye movement condition showed a sustained CDA that persisted in the original contralateral hemisphere even after the subjects had refixated. By contrast, when subjects shifted attention to the items in a new visual field, the CDA rapidly flipped in polarity, indicating that the item representations had been remapped to the other hemisphere.
Meeting abstract presented at VSS 2013