Perceptual Science Series
Investigating internal representations through spatiotemporal motor extrapolation
Monday, February 18, 2008, 01:00pm - 02:00pm
New York University , Department of Psychology
In recent work we showed that observers� estimates of the location and orientation of occluded contours are not always consistent with one another (Fulvio, Singh, & Maloney, 2008). This �dissociation� in visual processing of occluded contours is reminiscent of dissociations between perception and action claimed by Milner & Goodale (1998). I will present a study that extends previous perceptual work (Singh & Fulvio, 2005) to the motor domain. Subjects make speeded reaches, recorded by an Optotrak motion tracking device, to intersect a moving dot along its extrapolated trajectory with their fingertip. The extrapolated dot trajectories vary as a function of curvature, speed, and extrapolated distance. I will discuss the subjects� success in terms of these variables. I will also describe the kinematics of the movements and what they reveal about the underlying representations guiding them. Finally, I will relate the results back to the previous perceptual work to compare the role of task�perception versus action�and goal�perceptually complete versus reach the dot for a reward�on the nature of the extrapolated trajectories.
background reading: Goodale & Haffenden, 1997