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All Pulfrich-like illusions can be explained without joint encoding of motion and disparity

Lookup NU author(s): Professor Jenny ReadORCiD


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In the Pulfrich effect, an interocular time delay results in the perception of depth. Two modified versions, the stroboscopic Pulfrich effect and dynamic visual noise with a delay, are generally explained by postulating an early stage of space/time-inseparable filtering, encoding motion and disparity jointly. However, most disparity sensors in monkey V1 do not show joint motion/disparity encoding, and we recently showed that depth perception in the stroboscopic Pulfrich effect is equally compatible with space/time-separable filtering. Here, we demonstrate that this filtering can be implemented with a population of physiologically plausible energy model units. Similar results are obtained whether the neurons are pure disparity sensors ( like most V1 neurons) or joint motion/disparity sensors ( like MT). We also demonstrate that the dynamic noise stimulus produces correlations between the activity in pure disparity sensors, and in a separate population of pure motion sensors. These correlations are sufficient to explain the percept. Thus, joint encoding of motion and disparity is not required to explain depth perception in Pulfrich-like stimuli: a brain which encoded motion and disparity in entirely separate neuronal pathways could still experience all of these illusions.

Publication metadata

Author(s): Read JCA, Cumming BG

Publication type: Article

Publication status: Published

Journal: Journal of Vision

Year: 2005

Volume: 5

Issue: 11

Pages: 901-927

Print publication date: 01/01/2005

ISSN (print): 1534-7362

ISSN (electronic):

Publisher: ARVO


DOI: 10.1167/5.11.1


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