title: Default perception of high-speed motion.
abstract: When human observers are exposed to even slight motion signals followed by brief visual transients--stimuli containing no detectable coherent motion signals--they perceive large and salient illusory jumps. This visually striking effect, which we call "high phi," challenges well-entrenched assumptions about the perception of motion, namely the minimal-motion principle and the breakdown of coherent motion perception with steps above an upper limit called dmax. Our experiments with transients, such as texture randomization or contrast reversal, show that the magnitude of the jump depends on spatial frequency and transient duration--but not on the speed of the inducing motion signals--and the direction of the jump depends on the duration of the inducer. Jump magnitude is robust across jump directions and different types of transient. In addition, when a texture is actually displaced by a large step beyond the upper step size limit of dmax, a breakdown of coherent motion perception is expected; however, in the presence of an inducer, observers again perceive coherent displacements at or just above dmax. In summary, across a large variety of stimuli, we find that when incoherent motion noise is preceded by a small bias, instead of perceiving little or no motion--as suggested by the minimal-motion principle--observers perceive jumps whose amplitude closely follows their own dmax limits.
authors.affiliation: Laboratoire Psychologie de la Perception, Université Paris Descartes and Centre National de la Recherche Scientifique, 75006 Paris, France. mark.wexler@parisdescartes.fr
authors.forename: Mark
authors.initials: M
authors.lastname: Wexler
authors.forename: Andrew
authors.initials: A
authors.lastname: Glennerster
authors.forename: Patrick
authors.initials: P
authors.lastname: Cavanagh
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ito
authors.forename: Takeharu
authors.initials: T
authors.lastname: Seno
mesh_terms: D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011601:Psychophysics; D012684:Sensory Thresholds; D013997:Time Factors