The occlusion illusion: partial modal completion or apparent distance?

Palmer, S.E. and Brooks, Joseph L and Lai, K.S. (2007) The occlusion illusion: partial modal completion or apparent distance? Perception, 36 (5). pp. 650-669. ISSN 0301-0066. (Full text available)

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http://dx.doi.org/10.1068/p5694

Abstract

In the occlusion illusion, the visible portion of a partly occluded object (eg a semicircle partly hidden behind a rectangle) appears to be significantly larger than a physically identical region that is fully visible. This illusion may occur either because the visual system 'fills in' a thin strip along the occluded border (the partial-modal-completion hypothesis) or because the partly occluded object is perceived as farther away (the apparent-distance hypothesis). We measured the magnitude of the occlusion illusion psychophysically in several experiments to investigate its causes. The results of experiments 1-3 are consistent with the general proposal that the magnitude of the illusion varies with the strength of the evidence for occlusion, supporting the inference that it is due to occlusion. Experiment 4 provides a critical test between apparent-distance and partial-modal-completion explanations by determining whether the increase in apparent size of the occluded region results from a change in its perceived shape (due to the modal extension of the occluded shape along the occluding edge, as predicted by the partial-modal-completion hypothesis) or from a change in its perceived overall size (as predicted by the apparent-distance hypothesis). The results more strongly support the partial-modal-completion hypothesis.

Item Type: Article
Subjects: B Philosophy. Psychology. Religion > BF Psychology
Divisions: Faculties > Social Sciences > School of Psychology
Faculties > Social Sciences > School of Psychology > Cognitive Psychology
Depositing User: Joseph Brooks
Date Deposited: 29 Mar 2012 00:08
Last Modified: 26 Sep 2013 12:37
Resource URI: http://kar.kent.ac.uk/id/eprint/29188 (The current URI for this page, for reference purposes)
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