Overlapping features can be parsed on the basis of rapid temporal cues that produce stable emergent percepts.
When two overlapping displays alternate rapidly, it is difficult to resolve the temporal coincidence of objects, parts, or features. However, under certain conditions (at least for luminance-based stimuli) rapid temporal coincidence can be detected on the basis of stable emergent percepts in which parts that oscillate in phase appear more strongly grouped than (or appear distinct from) parts that oscillate out of phase. These emergent percepts appear as depth segregation, enhanced slow orientation rivalry, and oriented shimmer (a new phenomenon that cannot be explained in terms of conventional apparent motion or temporal contrast illusions). These percepts resulted in up to an eightfold decrease in the coincidence detection threshold (alternations as fast as 20 ms/frame or 25 Hz) relative to control conditions that did not yield them; these sensitivity enhancements are unlikely to be due to temporal probability summation. The results provide psychophysical evidence that temporal-phase information can contribute to the parsing of overlapping patterns.
Suzuki
Satoru
S
Department of Psychology, Northwestern University, 2029 Sheridan Road, Evanston, IL 60208, USA. satoru@northwestern.edu
Grabowecky
Marcia
M
D003463:Cues; D004192:Discrimination, Psychological / Q000502:physiology; D006801:Humans; D008029:Lighting; D009903:Optical Illusions / Q000502:physiology; D009949:Orientation / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology*