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PhD Thesis Defense Seminar

Monday, July 27, 2015
9:00 a.m.
K-307 Auditorium (3-6408), University of Rochester Medical Center

“Visual Capture and Recalibration of Auditory Spatial Perception”

Presented by: Adam K. Bosen
Supervised by: Gary Paige and William O’Neill

Vision and audition perform complementary roles in our perception of the environment. In healthy adults, vision provides an accurate and precise reference by which auditory space can be compared and adaptively adjusted to accomplish distinct contextual goals. The overarching goal of this dissertation was to quantify the behavioral processes that underlie audio-visual (AV) spatial perception.

There are two fundamental ways vision modifies auditory spatial perception. The first resolves disparities between paired AV targets. When there is a mismatch in location between auditory and visual targets, vision tends to "capture" auditory perception, biasing the auditory percept toward its visual counterpart. In an experimental environment the spatial limits of visual capture are tested by introducing disparities between auditory and visual targets and measuring the resultant percept. Visual capture was assessed by having subjects either make forced-choice judgments of whether auditory and visual targets emanate from the same location, or localize the auditory target. Results demonstrated that that the spatial boundaries of visual capture are sensitive to task objective, and therefore these methods of assessing visual capture are not equivalent.

A second form of AV interaction maintains spatial congruence across the senses. Prolonged exposure to spatial AV disparity produces a recalibration of auditory space to align it with visual perception. Recent results have implied that this effect also occurs after exposure to just a single AV disparity, but the relationship between these results remains unclear. Here, experiments demonstrate two superimposed processes: 1) a rapid effect that acts immediately following visual capture but decays within seconds, 2) a slow recalibration that accumulates over thousands of repetitions of a spatial AV disparity. Visual capture was further demonstrated to have distinct effects within AV pairs when compared to auditory targets presented after AV pairs. Together, these results demonstrate that visual capture and recalibration both act simultaneously but over different time scales to influence auditory spatial perception.

Together, these results characterize the distinct behavioral mechanisms that alter auditory spatial perception in response to spatial AV disparities. Understanding these behaviors helps guide investigation into their physiological roots, and the effects of sensory dysfunction on multisensory perception.