title: Dense sampling reveals behavioral oscillations in rapid visual categorization.
abstract: Perceptual systems must create discrete objects and events out of a continuous flow of sensory information. Previous studies have demonstrated oscillatory effects in the behavioral outcome of low-level visual tasks, suggesting a cyclic nature of visual processing as the solution. To investigate whether these effects extend to more complex tasks, a stream of "neutral" photographic images (not containing targets) was rapidly presented (20 ms/image). Embedded were one or two presentations of a randomly selected target image (vehicles and animals). Subjects reported the perceived target category. On dual-presentation trials, the ISI varied systematically from 0 to 600 ms. At randomized timing before first target presentation, the screen was flashed with the intent of creating a phase reset in the visual system. Sorting trials by temporal distance between flash and first target presentation revealed strong oscillations in behavioral performance, peaking at 5 Hz. On dual-target trials, longer ISIs led to reduced performance, implying a temporal integration window for object category discrimination. The "animal" trials exhibited a significant oscillatory component around 5 Hz. Our results indicate that oscillatory effects are not mere fringe effects relevant only with simple stimuli, but are resultant from the core mechanisms of visual processing and may well extend into real-life scenarios.
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento Corso Bettini 31, 38068 Rovereto TN, Italy.
authors.forename: Jan
authors.initials: J
authors.lastname: Drewes
authors.affiliation: School of Information Science, Yunnan University Cuihu Beilu, Kunming 650091, China.|Kunming Institute of Zoology Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming 650223, China.
authors.forename: Weina
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento Corso Bettini 31, 38068 Rovereto TN, Italy.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wutz
authors.affiliation: Center for Mind/Brain Sciences (CIMeC), University of Trento Corso Bettini 31, 38068 Rovereto TN, Italy.
authors.forename: David
authors.initials: D
authors.lastname: Melcher
mesh_terms: D001519:Behavior; D006801:Humans; D014796:Visual Perception