ERP Study Of The Difference In Derth Processing Between Gap Stereopsis And Binocular Disparity Stereopsis:The Regulatory Role Of Disparity

In the real world,many areas or objects can only be seen by one eye due to the difference in the lateral distance between the eyes(binocular disparity)and the occlusion between objects,which forms the monocular occlusion region.Gap stereopsis is a very important phenomenon in the monocular occlusion region,referring to the fact that the gap between two objects can only be seen by one eye and not the other.Some of the previous studies on gap stereopsis support the binocular disparity theory,suggesting that gap stereopsis has the same processing mechanism as binocular disparity.However,some studies hold the opposite attitude,believing that gap stereopsis is related to depth cues such as occlusion.So far,the depth processing mechanism of gap stereopsis is still a controversial issue.Considering that disparity is one of the most important clues in stereopsis,and there is a good correspondence between the gap in gap stereopsis and the disparity in binocular disparity stereopsis.In Study 1,we combined behavioral data and electroencephalogram(EEG)characteristics to investigate the effect of disparity on the depth processing mechanism of gap stereopsis and binocular disparity stereopsis.Study 2further examined the effects of attention on the depth processing mechanisms of gap stereopsis and binocular disparity stereopsis on the basis of Study 1.This paper attempts to reveal the depth processing mechanism of gap stereopsis by investigating the behavior and EEG characteristics of gap stereopsis,so as to enrich and improve the theoretical basis for the study of monocular occlusion region.Study 1 used 3(stimulus types: gap stereopsis,binocular disparity stereopsis and flat stimuli)× 3(disparity: 8.7,13.05 and 17.4 arcmin)within-subject experimental design to statistically analyze behavioral data(reaction time and accuracy)as well as event related potential(ERP)results(latency and amplitude of P1,P2,N170,and N270 components)of the participants.The results showed that(1)Disparity affected individual stereopsis processing and had significant interaction with stimulus types,which might be related to task difficulty and cognitive resource allocation.(2)Stereopsis stimuli(including gap stereopsis and binocular disparity stereopsis)and flat stimuli were significantly different in both behavioral outcomes(accuracy and reaction time)and the results of ERP(P2,N170,and N270 components),suggesting different visual processing mechanisms in stereopsis and flat.(3)Gap stereopsis and binocular disparity stereopsis in stereopsis stimuli differed significantly in accuracy,reaction time,and P2 amplitude.This suggests that the depth processing mechanisms of gap stereopsis and binocular disparity stereopsis may not be identical at the perceptual processing stage.And the P2 component may play an important role in understanding the differences in depth processing mechanisms between gap stereopsis and binocular disparity stereopsis.(4)P2 component not only plays an important role in stereopsis processing,but is also closely related to attention processing,suggesting that the differences between gap stereopsis and binocular disparity stereopsis in P2 may not be due to differences in stereopsis processing mechanisms,but may be influenced by attention.In Study 2,an improved Posner visual-spatial cueing paradigm was used,and 3(stimulus types: gap stereopsis,binocular disparity stereopsis and flat stimuli)×2(cue: cue condition and un-cued condition)within-subject experimental design was used to examine whether attention influenced the depth processing mechanisms of gap stereopsis and binocular disparity stereopsis.The results showed that:(1)Results inconsistent with those of Study 1 were found in both behavioral and ERP results,and the amplitude of the P300 component evoked by gap stereopsis was significantly lower than that of binocular disparity stereopsis and flat stimuli,suggesting that attention may influence the depth processing mechanisms of gap stereopsis and binocular disparity stereopsis.(2)The results of the P2 component in Study 2 were consistent with those of Study 1,suggesting that the P2 component does reflect differences in the depth processing mechanisms of gap stereopsis and binocular disparity stereopsis,independent of attention.In summary,the following conclusions are drawn:(1)Disparity can affect the depth processing mechanism of gap stereopsis and binocular disparity stereopsis.And the results of ERP show that the depth processing mechanisms of gap stereopsis and binocular disparity stereopsis are the same at the early processing stage,with some differences at the perceptual stage.(2)There are potential effects of individual attentional states on the depth processing mechanisms of gap stereopsis and binocular disparity stereopsis.The current study combined behavioral experiments and neuroimaging techniques to further clarify the depth processing mechanism of gap stereopsis,which can provide new perspectives and references for future studies on the depth processing mechanism of monocular occlusion region.In addition,this study also found that the disparity has an impact on the depth processing of individuals.This suggests that we need to consider the disparity differences of different individuals when designing virtual reality scenes to ensure that they can have the best stereopsis experience.