Auditory capture of visual motion
Single Paper Presentation

Mark McCourt
Department of Psychology, North Dakota State University

Brian Pasieka
Department of Psychology, North Dakota State University

     Abstract ID Number: 133
     Full text: Not available
     Last modified: May 20, 2003

Abstract
Visual perception is altered by auditory stimuli. We asked: 1) if the perceived direction of visual motion could be influenced by auditory signals; and 2) if motion detection thresholds were altered by concurrent sound motion. The visual stimulus was a spatiotemporally vignetted sinewave grating. Grating "frames" were combined into short movies (3 frames, 375 ms duration). Between successive frames the spatial phase of the grating was altered: interframe phase shifts of 180 deg produced grating motion that was ambiguous and bistable owing to equal rightward and leftward motion energy. Interframe phase shifts of 90 or 270 deg produced unambiguous unidirectional apparent motion. Visual motion was paired with binaural amplitude-gated bursts of pink noise to create sounds whose motion in 3D auditory space could be manipulated (rightward sound motion, leftward sound motion, static sound, and no sound). Observers judged the direction of visual motion. Contrast thresholds for detecting rightward grating motion were obtained under similar auditory conditions. The perceived direction of visual motion was strongly influenced by concurrent auditory motion: auditory motion “captured” ambiguous visual motion. Visual motion detection thresholds were not, however, influenced by auditory motion. The level at which auditory-visual interactions occur is discussed.