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Jan Drewes; Oscillations in behavioral performance for rapidly presented natural scenes. Journal of Vision 2015;15(12):1402. doi: 10.1167/15.12.1402.
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© 2017 Association for Research in Vision and Ophthalmology.
Humans are capable of rapidly extracting object and scene category information from visual scenes, raising the question of how the visual system achieves this high speed performance.
Recently, several studies have demonstrated oscillatory effects in the behavioral outcome of low-level visual tasks, hinting at a possibly cyclic nature of visual processing. Here we present evidence that these oscillatory effects may also be manifest in a more complex target discrimination task using natural scenes as stimuli. In our experiment, a stream of neutral images (containing neither vehicles nor animals) was rapidly presented centrally at 20 ms/image. Embedded in this image stream were one or two presentations of a target image randomly selected from two categories (vehicles and animals) and subjects were asked to decide the target image category. On trials with two presentations, the ISI was varied systematically from 0 to 600ms. At a varying time prior to the first target presentation, the screen background was flashed with the intent of creating a phase reset in the visual system. When sorting trials by the temporal distance between flash and first target presentation, a strong oscillation in behavioral performance emerged, peaking at 10Hz, consistent with previous studies showing an oscillation in detection threshold. On trials with two targets, longer ISIs between the led to reduced detection performance, implying a temporal integration window for object category discrimination. However, the “animal” trials additionally exhibited a significant oscillatory component at around 5Hz. These findings suggest that there are alternating optimal and non-optimal time periods for which stimulus repetition and integration can improve visual recognition, perhaps due to recurrent processing in complex visual scene perception.”
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