Freeman, Tom C. A. ![]() |
Abstract
During smooth pursuit eye movement, observers often misperceive velocity. Pursued stimuli appear slower (Aubert-Fleishl phenomenon [ [1] and [2] ]), stationary objects appear to move (Filehne illusion [3]), the perceived direction of moving objects is distorted (trajectory misperception [4]), and self-motion veers away from its true path (e.g., the slalom illusion [5]). Each illusion demonstrates that eye speed is underestimated with respect to image speed, a finding that has been taken as evidence of early sensory signals that differ in accuracy [ [4] , [6] , [7] , [8] , [9] , [10] and [11] ]. Here we present an alternative Bayesian account, based on the idea that perceptual estimates are increasingly influenced by prior expectations as signals become more uncertain [ [12] , [13] , [14] and [15] ]. We show that the speeds of pursued stimuli are more difficult to discriminate than fixated stimuli. Observers are therefore less certain about motion signals encoding the speed of pursued stimuli, a finding we use to quantify the Aubert-Fleischl phenomenon based on the assumption that the prior for motion is centered on zero [ [16] , [17] , [18] , [19] and [20] ]. In doing so, we reveal an important property currently overlooked by Bayesian models of motion perception. Two Bayes estimates are needed at a relatively early stage in processing, one for pursued targets and one for image motion.
Item Type: | Article |
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Date Type: | Publication |
Status: | Published |
Schools: | Psychology |
Subjects: | R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry |
Uncontrolled Keywords: | SYSNEURO |
Publisher: | Elsevier |
ISSN: | 0960-9822 |
Last Modified: | 18 Oct 2022 12:53 |
URI: | https://orca.cardiff.ac.uk/id/eprint/11522 |
Citation Data
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