Motion capture of luminance stimuli by equiluminous color gratings and by attentive tracking.
Two experiments demonstrated motion capture of luminance-defined dots by gratings with no net luminance-based motion. In a series of two-frame experimental trials, we superimposed bright dots and a color grating rotating in opposite directions. Capture was observed at equiluminance and was facilitated by the presence of color in gratings over a range of luminance contrasts. In a second experiment, observers noted that when a counterphase grating was tracked in either direction with attention, the superimposed dots were captured in that direction. These results suggest motion capture is supported not only by luminance-based motion, but also by color- and attention-based motion. Indeed, we suggest that the most parsimonious explanation is that all capture is mediated by attention.
Department of Psychology, Harvard University, Cambridge, MA 02138.
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JC
Culham
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Cavanagh
D001288:Attention; D003118:Color Perception / Q000502:physiology*; D005403:Fixation, Ocular; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D009903:Optical Illusions / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011594:Psychometrics; D012684:Sensory Thresholds / Q000502:physiology