Purchase this article with an account.
Fredrik Allenmark, Jenny Read; The limit of spatial resolution for joint stereo disparity / motion perception. Journal of Vision 2010;10(7):365. doi: 10.1167/10.7.365.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Human spatial resolution for luminance gratings – the ability to distinguish black-and-white stripes from gray –can reach 50 cycles per degree (cpd; Campbell & Green 1965, J Physiol 181:576). The equivalent resolution for stereo disparity is an order of magnitude lower: depth corrugations defined by binocular disparity cannot be perceived beyond about 4 cpd (Tyler 1974, Nature 251:140; Banks et al. 2004, J Neurosci 24:2077; Bradshaw & Rogers 1999, Vision Res 39:3049). Both these limits are believed to be set by the properties of cells in primary visual cortex (V1): stereo resolution by the area of their receptive fields, and luminance resolution by the arrangement of ON/OFF subregions within receptive fields (Nienborg & Cumming 2003, J Neurosci 24:2065). Here, we examine the spatial resolution for perceiving, not motion or disparity alone, but the correlations between both. The stimuli were random-dot stereograms depicting two transparent depth planes made up of dots streaming at constant speed, either left or right. Both directions of motion were always present everywhere in the visual field, but for the target stimulus they were locally segregated into depth planes (e.g. front plane moving to the left, back moving right), while for the control stimulus, both front and back planes everywhere consisted of two transparent directions of motion. This task requires observers to extract disparity contingent upon motion direction. To find the resolution limit, we alternated the motion direction within each depth plane for the target stimulus, i.e. the target consisted of horizontal strips, alternately front-leftwards/back-rightwards and front-rightwards/back-leftwards. We examined how performance on this task varied as we reduced the height of the strips. We compared this with a task with the same motion energy but which could be performed based solely on the disparity. We find that the high-frequency cut-off is lower for the joint motion/disparity task.
This PDF is available to Subscribers Only