Role of vergence eye movements in the visual recognition of long time duration.

When viewing dichoptic stimuli in long time duration, visual percepts are always the alternation between the left and right eye inputs, while not the combination. This is known as binocular rivalry. An efficient coding theory reported that binocular visual inputs can be combined into binocular summation (S) and difference (S) channels in V1 brain area. In this study, we used specially designed stimuli as the previous study, in which monocular inputs caused ambiguous percepts, but S and S channels had unambiguous percepts. We aim to investigate whether the visual percepts alter between S and S channels in long time duration and whether vergence eye movements are involved in the process. To do so, the stimuli were presented in 300-s time duration in a trial, and a binocular eye tracker was used to record eye information. Participants' real-time behavioral responses about the visual percepts and binocular information were recorded simultaneously. The results show there are perceptual flips between S and S channels in both central and long time viewing conditions. More importantly, in central vision there are vergence eye movements before perceptual flips, suggesting the involvement of high level visual attention; the time of a perceptual flip from S is shorter than that of a flip from S, which might be due to different involvements of visual attention, indicating a bias of feedback connection from higher brain areas for visual attention to S channel. Since S and S dominated signals can be carried by different types of binocular neurons, our results provide new insights into high level visual attention and binocular neurons in V1 brain area by using specially designed dichoptic stimuli and eye vergence as measuring tools.