A left visual field advantage in perception of gaze direction.

Previous work has found a left visual field (LVF) advantage for various judgements on faces, including identity and emotional expression. This has been related to possible right-hemisphere specialisation for face processing, and it has been proposed that this might reflect configural processing. We sought to determine whether a similar LVF advantage may also exist for gaze perception. In two experiments, normal adult subjects made judgements for seen gaze direction (left, right or straight). To assess how visual field may influence perception of gaze direction, eye stimuli were briefly presented unilaterally or bilaterally. In the latter case, the gaze direction of the two seen eyes could be congruent or incongruent (i.e. the two eyes could gaze in the same or different directions). For unilateral displays, performance was more accurate for LVF stimuli than RVF. With bilateral incongruent gaze, the LVF eye influenced judgements more strongly than the RVF eye. No such LVF advantage was found in a control experiment, in which subjects judged pupil size for similar eye stimuli. Taken together, these results reveal a LVF advantage for perception of gaze direction. Since only the eye region was visible, our results cannot be due to a LVF bias in processing the entire face context. Instead they suggest lateralisation specifically in processing the direction of seen gaze.