WHO:	Jeff Saunders , Postdoc working w/ David Knill
TOPIC:	IS OPTIC FLOW USED TO CONTROL WALKING?
ABSTRACT:	Optic flow can provide a strong cue to self-motion, and has been assumed to play an important role in guiding locomotion. However, there has recently been some debate about whether or not perceived heading from optic flow contributes to control of walking. I will review previous results that have led to the questioning of the role of optic flow, and present data from two new experiments that I have recently conducted in the VR lab. Subjects walked to visible targets in a dynamic virtual environment. Visual feedback was presented with a head mounted display system, and the simulated views were updated in real-time based on data from an optical head tracking system. In this setup, visual and nonvisual information about self-motion could be dissociated by changing the mapping from physical to visual space. Results suggest that subjects guide walking by directing their physical heading toward the visual target, rather than aligning their visual heading toward the target. The apparent lack of contribution from optic flow contrasts with findings for other related tasks, like posture control or simulated driving. I will discuss possible explanations for this difference, and suggest other roles for optic flow information in guiding movement. 
WHEN:	12/12/2003 12:00:00 PM
WHERE:	Meliora 269

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