Biological movements look uniform: evidence of motor-perceptual interactions

J Exp Psychol Hum Percept Perform. 1992 Aug;18(3):603-23. doi: 10.1037//0096-1523.18.3.603.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acceleration
  • Adult
  • Attention*
  • Depth Perception*
  • Discrimination Learning
  • Female
  • Humans
  • Kinesthesis
  • Male
  • Mental Recall
  • Motion Perception*
  • Optical Illusions*
  • Orientation*
  • Psychomotor Performance*
  • Psychophysics