title: Failure of signed chromatic apparent motion with luminance masking.
abstract: It has been suggested that there are two types of chromatic motion mechanisms: signed chromatic motion, in which correspondence across successive frames is based on chromatic content of image regions, and unsigned chromatic motion based on movement of chromatically-defined borders. We investigate whether signed and unsigned red-green chromatic motion are mediated by a genuinely chromatic mechanism. Direction discrimination of signed and unsigned red-green chromatic motion were measured in the presence of a dynamic luminance masking noise. Increasing the luminance noise contrast systematically impaired signed motion, regardless of contrast and speed. This result suggests that signed red-green chromatic motion is derived from a luminance-based signal, rather than a genuinely chromatic motion mechanism. In the case of unsigned chromatic motion, there is no effect of luminance masking noise, indicating there exists a genuine chromatic mechanism for second-order motion perception.
authors.affiliation: Department of Ophthalmology, McGill Vision Research, McGill University, 687 Pine Avenue West, Room H4-14, Que., H3A 1A1, Montreal, Canada.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yoshizawa
authors.forename: Kathy T
authors.initials: KT
authors.lastname: Mullen
authors.forename: Curtis L
authors.initials: CL
authors.lastname: Baker
mesh_terms: D003118:Color Perception; D004192:Discrimination, Psychological; D006801:Humans; D008029:Lighting; D009039:Motion Perception; D010470:Perceptual Masking; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics