title: Synesthetically induced colors evoke apparent-motion perception.
abstract: Synesthesia is a condition in which certain otherwise normal individuals see colors when they hear tones, or, when they look at black-and-white numbers, each number is tinged with a specific color (eg 5 is red and 2 is green). We constructed a display in which a random matrix of 5s had a vertical column of 2s 'embedded' in it. This was shown in frame 1 of a movie, followed by a similar display in frame 2 in which the element locations were uncorrelated but the bar as a whole was shifted horizontally. When normal subjects viewed the display, they just saw random jitter or twinkle; there was no impression of a bar moving horizontally. But, when our subject (JC) who had grapheme-color synesthesia viewed the display, he reported seeing a bar moving left or right depending on the trial. We conclude that, in at least some subjects, a synesthetically induced color that does not exist on the retina can nonetheless influence motion perception.
authors.affiliation: Center for Brain and Cognition, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0109, USA. vramacha@ucsd.edu
authors.forename: Vilayanur S
authors.initials: VS
authors.lastname: Ramachandran
authors.forename: Shai
authors.initials: S
authors.lastname: Azoulai
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003118:Color Perception / Q000502:physiology*; D003463:Cues; D006801:Humans; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009903:Optical Illusions; D010468:Perceptual Disorders / Q000523:psychology*; D012684:Sensory Thresholds / Q000502:physiology