Abstract
The visual system uses a dynamic process of actively searching the visual environment to select perceptually-relevant events. Previous studies suggest that right hemisphere is mainly involved in visual search tasks; however, little is known about ‘how’ this hemispheric asymmetry occurs. We hypothesized that a part of visual information should be transferred from left hemisphere (LH) to right hemisphere (RH) for detailed attentional processing during serial search. The first experiment was designed to psychophysically probe this conjecture. In this experiment, a conjunction search array (presented to the left or right visual hemifield) was followed by another search array (presented on the same or opposite side). Presentation of the first array to LH and the second array to RH resulted in longer reaction times (compared to RH-LH order) when the temporal separation between the two arrays was short. This finding shows a central role for right hemisphere in attentional representations of both left and right hemifields. In the second experiment, a conjunction search array was presented in two temporal epochs. Subjects made a saccade between the two epochs while the array was maintained in the same spatial location (spatiotopic condition). In the control condition, the location of array was changed while subjects had constant fixation. Reaction times were faster in the spatiotopic condition mostly when the stimulus of the first epoch was presented to RH. This asymmetry demonstrates that right hemisphere also plays a dominant role in spatiotopic representations during dynamic serial search.