title: Illusory percepts of moving patterns due to discrete temporal sampling.
abstract: Continuously, moving objects under continuous illumination can be seen to move in a direction opposite to their actual motion. This illusory reversed motion can be explained as due to discrete temporal sampling of the moving stimulus by the visual system. If temporal sampling lies behind the illusory motion, then the probability of illusory motion should depend on the temporal frequency of the motion stimulus. By presenting contracting bull's-eye gratings of various spatial frequencies we were able to tease apart the drift speed and temporal frequency. The prevalence of illusory percepts depended on the temporal frequency, not the speed. The data suggest that the human visual system samples the incoming stimulation at a rate near 16 Hz.
authors.affiliation: Simulation and Modelling Section, DRDC Toronto, 1133 Sheppard Avenue West, P.O. Box 2000, Toronto, Ont., Canada M3M 3B9. william.simpson@drdc.gc.ca
authors.forename: William A
authors.initials: WA
authors.lastname: Simpson
authors.forename: Uma
authors.initials: U
authors.lastname: Shahani
authors.forename: Velitchko
authors.initials: V
authors.lastname: Manahilov
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology; D006801:Humans; D009038:Motion; D009039:Motion Perception / Q000502:physiology*; D009068:Movement; D009949:Orientation; D010775:Photic Stimulation / Q000379:methods; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology*