title: Biological movements look uniform: evidence of motor-perceptual interactions.
abstract: Six experiments demonstrate a visual dynamic illusion. Previous work has shown that in 2-dimensional (2D) drawing movements, tangential velocity and radius of curvature covary in a constrained manner. The velocity of point stimuli is perceived as uniform if and only if this biological constraint is satisfied. The illusion is conspicuous: The variations of velocity in the stimuli exceed 200%. Yet movements are perceived as uniform. Conversely, 2D stimuli moving at constant velocity are perceived as strongly nonuniform. The illusion is robust: Exposure to true constant velocity fails to suppress it. Results cannot be explained entirely by the kinetic depth effect. The illusion is evidence of a coupling between motor and perceptual processes: Even in the absence of any intention to perform a movement, certain properties of the motor system implicitly influence perceptual interpretation of the visual stimulus.
authors.affiliation: Department of Psychobiology, Université de Genève, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Viviani
authors.forename: N
authors.initials: N
authors.lastname: Stucchi
mesh_terms: D000054:Acceleration; D000328:Adult; D001288:Attention; D003867:Depth Perception; D004193:Discrimination Learning; D005260:Female; D006801:Humans; D007699:Kinesthesis; D008297:Male; D011939:Mental Recall; D009039:Motion Perception; D009903:Optical Illusions; D009949:Orientation; D011597:Psychomotor Performance; D011601:Psychophysics