Elsevier

Vision Research

Volume 33, Issue 11, July 1993, Pages 1481-1490
Vision Research

An illusory transformation of optic flow fields

https://doi.org/10.1016/0042-6989(93)90141-IGet rights and content

Abstract

We compared a human observer's ability to locate the focus of expansion (FOE) of a radial optic flow field when this flow field was either combined with, or overlapped by, planar motion. With combined stimuli, in which the FOE was displaced in the direction opposite to the planar motion, subjects accurately located the displaced FOE. With overlapping (transparent) stimuli and the FOE remaining in the center of the display, we found an illusory transformation of the radial pattern: the focus of expansion appeared to be shifted in the direction of the planar motion. The speed of both the planar and radial patterns of motion influenced the illusion. Presence or absence of visual fixation had little effect. We suggest that this illusion might provide a clue as to the way the brain processes planar and radial motion which might in turn be relevant to the interaction of the planar and radial motion components of optic flow fields.

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  • Cited by (0)

    A brief report of this work has appeared previously (Duffy & Wurtz, 1993).

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