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Effects on orientation perception of manipulating the spatio-temporal prior probability of stimuli

Lookup NU author(s): Dr Kun Guo, Dr Angel Nevado, Dr Robert Robertson, Maribel Pulgarin Montoya, Professor Alexander Thiele, Professor Malcolm Young


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Spatial and temporal regularities commonly exist in natural visual scenes. The knowledge of the probability structure of these regularities is likely to be informative for an efficient visual system. Here we explored how manipulating the spatio-temporal prior probability of stimuli affects human orientation perception. Stimulus sequences comprised four collinear bars (predictors) which appeared successively towards the foveal region, followed by a target bar with the same or different orientation. Subjects' orientation perception of the foveal target was biased towards the orientation of the predictors when presented in a highly ordered and predictable sequence. The discrimination thresholds were significantly elevated in proportion to increasing prior probabilities of the predictors. Breaking this sequence, by randomising presentation order or presentation duration, decreased the thresholds. These psychophysical observations are consistent with a Bayesian model, suggesting that a predictable spatio-temporal stimulus structure and an increased probability of collinear trials are associated with the increasing prior expectation of collinear events. Our results suggest that statistical spatio-temporal stimulus regularities are effectively integrated by human visual cortex over a range of spatial and temporal positions, thereby systematically affecting perception. © 2004 Elsevier Ltd. All rights reserved.

Publication metadata

Author(s): Guo K, Nevado A, Robertson RG, Pulgarin M, Thiele A, Young MP

Publication type: Article

Publication status: Published

Journal: Vision Research

Year: 2004

Volume: 44

Issue: 20

Pages: 2349-2358

ISSN (print): 0042-6989

ISSN (electronic): 1878-5646

Publisher: Pergamon


DOI: 10.1016/j.visres.2004.04.014

PubMed id: 15246751


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