title: Measurement of rate of expansion in the perception of radial motion.
abstract: Optic flow generated by rigid surface patches can be decomposed into a small number of elementary motion types. In these experiments, we show that the human visual system can evaluate expansion, one of these motion types, metrically. Moreover, we show that the discrimination of rates of expansion are spatially local. Because the estimation of the focus of expansion is somewhat imprecise, this locality sometimes produces predictable errors in the estimation of rate of expansion. One can make predictions like this with a model adapted from one previously developed for angular-velocity discrimination.
authors: Neuroscience Graduate Program, University of Southern California, Hedco Neuroscience Building, MC 2520, Los Angeles, CA 90089-2520, USA. wurfel@usc.edu
authors: Jeff D
authors: JD
authors: Wurfel
authors: José F
authors: JF
authors: Barraza
authors: Norberto M
authors: NM
authors: Grzywacz
mesh_terms: D004192:Discrimination, Psychological; D005403:Fixation, Ocular / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D009039:Motion Perception / Q000502:physiology*; D010470:Perceptual Masking / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D012399:Rotation; D013997:Time Factors