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Kyle W. Killebrew, Hannah R. Moser, Scott R. Sponheim, Michael-Paul Schallmo; Faster switch rates in psychosis for bi-stable perception during a structure-from-motion task. Journal of Vision 2020;20(11):392. https://doi.org/10.1167/jov.20.11.392.
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Bi-stable perception occurs when the same physical stimulus evokes two alternating dominant percepts. Bi-stability has been proposed to result from competition (e.g., mutual inhibition) between the two neural populations representing the distinct percepts. Prominent theories suggest that abnormal visual perception (e.g., hallucinations) among patients with psychosis may result from impaired inhibitory processes in early visual cortex. We hypothesized that these patients would perceive alternations between the two dominant percepts of a bi-stable stimulus at a faster rate than controls. We examined bi-stable perception using a structure-from-motion task in 41 patients with psychosis (e.g., schizophrenia or bipolar disorder), 25 unaffected biological relatives, and 33 healthy controls. Specifically, we presented a rotating cylinder illusion and asked participants to respond whenever they saw a change in the direction of rotation. The patient and relative groups showed faster switch rates during this bi-stable illusion compared to healthy controls. Additionally, there were no differences in switch rates between the groups in a second version of the task, in which overt depth information was added and physical direction switches were present. Excluding 17 subjects based on performance in this second task did not alter our pattern of results. Using a computational model, based on one proposed for binocular rivalry by Said and Heeger (2013), we also demonstrated results that closely matched performance for patients and controls. Our results appear consistent with a reduction in suppressive neural processes (e.g., mutual inhibition or adaptation) during motion perception among people with psychosis. Faster switch rates among relatives of people with psychosis may suggest a role for genetic liability in resolving ambiguous visual percepts.
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