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Time course of amodal completion revealed by a...
Journal article

Time course of amodal completion revealed by a shape discrimination task

Abstract

We measured the extent of amodal completion as a function of stimulus duration over the range of 15–210 msec, for both moving and stationary stimuli. Completion was assessed using a performancebased measure: a shape discrimination task that is easy if the stimulus is amodally completed and difficult if it is not. Specifically, participants judged whether an upright rectangle was longer horizontally or vertically, when the rectangle was unoccluded, occluded at its corners by four negative-contrast squares, or occluded at its corners by four zero-contrast squares. In the zero-contrast condition, amodal completion did not occur because there were no occlusion cues; in the unoccluded condition, the entire figure was present. Thus, comparing performance in the negative-contrast condition to these two extremes provided a quantitative measure of amodal completion. This measure revealed a rapid but measurable time course for amodal completion. Moving and stationary stimuli took the same amount of time to be completed (≈ 75 msec), but moving stimuli had slightly stronger completion at long durations.

Authors

Murray RF; Sekuler AB; Bennett PJ

Journal

Psychonomic Bulletin & Review, Vol. 8, No. 4, pp. 713–720

Publisher

Springer Nature

Publication Date

January 1, 2001

DOI

10.3758/bf03196208

ISSN

1069-9384

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