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Huayun Li, Dongchuan Yu, Laipeng Jin, Xin Gao; Factors that influence depth from Panum's limiting case: An ERP analysis. Journal of Vision 2016;16(12):844. doi: 10.1167/16.12.844.
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© 2017 Association for Research in Vision and Ophthalmology.
While Panum's limiting case has been the focus of considerable study, only recently has it been discovered that, in addition to horizontal disparity, the final percept of depth is influenced by i) the vertical gradient of disparity and ii) the degree of conflict between 2D and 3D shape cues (Li et al., 2012). In this study, we evaluate correlates of neural activity in an attempt to clarify how these variables determine depth percepts in Panum's limiting case. Participants were shown a series of stereograms with variable vertical gradient and 2D/3D cue conflict. On each trial they indicated which of several percepts they observed while we recorded electroencephalograms using Scan 4.0 software. It has been shown that the amplitude of the N170 is strongly influenced by physical stimulus properties and N270 activity can be elicited by stimulus attribute conflicts. Therefore we chose to focus on these two components in our analyses. Our behavioural results replicated those of (Li et al, 2012). Our ERP analysis showed significant changes in the amplitude of the N170 component as a function of the vertical gradient; amplitudes were larger when the vertical gradient was small. There was also a significant effect of cue conflict and an interaction between the two factors on the N170. However, changes in the N270 component were only significant for the cue conflict manipulation. The mean amplitude of N270 decreased as the degree of cue conflict decreased. These results suggest that these factors affect perceived depth at different points in time: the vertical gradient disparity at an early stage of processing (N170) and cue conflict impacts processing at least at two stages (N170 and N270). Together, our behavioural and neural correlate data support the proposal that the binocular matching process underlying Panum's phenomena reflects several factors, which have different time courses.
Meeting abstract presented at VSS 2016
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