title: Motion: the long and short of it.
abstract: Several authors have proposed that motion is analyzed by two separate processes: short-range and long-range. We claim that the differences between short-range and long-range motion phenomena are a direct consequence of the stimuli used in the two paradigms and are not evidence for the existence of two qualitatively different motion processes. We propose that a single style of motion analysis, similar to the well known Reichardt and Marr-Ullman motion detectors, underlies all motion phenomena. Although there are different detectors of this type specialized for different visual attributes (namely first-order and second-order stimuli), they all share the same mode of operation. We review the studies of second-order motion stimuli to show that they share the basic phenomena observed for first-order stimuli. The similarity across stimulus types suggests, not parallel streams of motion extraction, one short-range and passive and the other long-range and intelligent, but a concatenation of a common mode of initial motion extraction followed by a general inference process.
authors.affiliation: Département de Psychologie, Université de Montréal, Québec, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Cavanagh
authors.forename: G
authors.initials: G
authors.lastname: Mather
mesh_terms: D000221:Adaptation, Ocular / Q000502:physiology; D000818:Animals; D003118:Color Perception / Q000502:physiology; D006801:Humans; D008027:Light; D009039:Motion Perception / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology