Distortions of Visual and Auditory Space Following Motion Adaptation

Ross Deas, Visual Neuroscience Group, School of Psychology, University of Nottingham, NG72JD

Abstract
There is growing evidence that the neural mechanisms which encode visual and auditory motion are more similar than previously thought. In this study, we examine the effects of motion adaptation on the perceived location of subsequently presented stationary stimuli. Following adaptation to unidirectional visual motion, the perceived position of a stationary stimulus appears offset in the direction opposite to the adapting motion, showing a direct interaction between the mechanisms which encode motion and spatial position. This motion induced shift is velocity dependent and peaks at ~10 deg/s. Using individual head related transfer functions (HRTF) we created auditory motion stimuli in the horizontal plane which could vary in angular velocity, spatial extent and duration. Subjects adapted to unidirectional auditory motion and then made a spatial localization judgment of a stationary auditory stimulus relative to the midline. Consistent with visual findings, all subjects showed a marked direction dependant shift in perceived auditory position, relative to a ‘no adaptation’ baseline measure. The velocity tuning functions for this effect showed a striking similarity to their visual counterparts suggesting a common processing scheme for these effects. Subsequent experiments investigated the cross-modal effects of motion adaptation on position coding. (this project was supported by the wellcome trust)

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