Is optic flow used in an optimal manner for control of walking?
Thu, June 20, 2013 • 12:00 PM - 1:00 PM • SEA 4.244
The University of Texas at Austin
Center for Perceptual Systems Seminar Series
"Is optic flow used in an optimal manner for control of walking?"
Jeffrey A. Saunders, Ph.D.
Department of Psychology
University of Hong Kong
Bag Lunch Talk
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Abstract: Walking toward a goal is a common task that could be controlled in different ways. One possible strategy would be to use visual information about self-motion provided by global optic flow. Observers could steer to keep the heading direction specified by optic flow aligned with the goal direction. Alternative strategies would be to use only the relative motion of the goal, or to steer based on non-visual information about self-motion. Previous studies have used cue conflict conditions to dissociated these strategies conditions and found mixed results. Although global optic flow is a powerful cue for self-motion, some studies have found little or no influence on control of walking. I hypothesized that this might reflect optimal use of visual and non-visual information. For optimal integration, different sources of information would contribute according to their reliability. Optimal use of optic flow would depend on not only the ability to perceive self-motion from vision, but also the ability to perceive self-motion without vision. I present new experiments that measured reliability of walking with and without visual feedback, and the relative weighting of visual feedback in cue conflict conditions. I found that observers were capable of walking toward a target with high precision, comparable to ability to judge heading direction from optic flow. Because of the high reliability of walking without vision, optimal integration predicts that the influence of optic flow would be limited and sensitive to the quality of visual information. Results from cue conflict conditions were consistent with optimal predictions. The limited influence of optic flow observed here, and in previous studies, could be explained by optimal use of visual and non-visual information.