title: Three-systems theory of human visual motion perception: review and update.
abstract: Lu and Sperling [Vision Res. 35, 2697 (1995)] proposed that human visual motion perception is served by three separate motion systems: a first-order system that responds to moving luminance patterns, a second-order system that responds to moving modulations of feature types-stimuli in which the expected luminance is the same everywhere but an area of higher contrast or of flicker moves, and a third-order system that computes the motion of marked locations in a "salience map," that is, a neural representation of visual space in which the locations of important visual features ("figure") are marked and "ground" is unmarked. Subsequently, there have been some strongly confirmatory reports: different gain-control mechanisms for first- and second-order motion, selective impairment of first- versus second- and/or third-order motion by different brain injuries, and the classification of new third-order motions, e.g., isoluminant chromatic motion. Various procedures have successfully discriminated between second- and third-order motion (when first-order motion is excluded): dual tasks, second-order reversed phi, motion competition, and selective adaptation. Meanwhile, eight apparent contradictions to the three-systems theory have been proposed. A review and reanalysis here of the new evidence, pro and con, resolves the challenges and yields a more clearly defined and significantly strengthened theory.
authors.affiliation: Department of Psychology, University of Southern California, Los Angeles 90089-1061, USA. zhonglin@rcf.usc.edu
authors.forename: Z L
authors.initials: ZL
authors.lastname: Lu
authors.forename: G
authors.initials: G
authors.lastname: Sperling
mesh_terms: D015350:Contrast Sensitivity / Q000502:physiology; D006801:Humans; D008027:Light; D008959:Models, Neurological; D008960:Models, Psychological; D009039:Motion Perception / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*