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Appears in Collections:Psychology Journal Articles
Peer Review Status: Refereed
Title: Misperception of aspect ratio in binocularly viewed surfaces
Authors: Hibbard, Paul
Goutcher, Ross
O'Kane, Lisa
Scarfe, Peter
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Keywords: Horizontal–vertical illusion
Binocular disparity
Aspect ratio
Issue Date: Oct-2012
Publisher: Elsevier
Citation: Hibbard P, Goutcher R, O'Kane L & Scarfe P (2012) Misperception of aspect ratio in binocularly viewed surfaces, Vision Research, 70, pp. 34-43.
Abstract: The horizontal–vertical illusion, in which the vertical dimension is overestimated relative to the horizon- tal direction, has been explained in terms of the statistical relationship between the lengths of lines in the world, and the lengths of their projections onto the retina (Howe & Purves, 2002). The current study shows that this illusion affects the apparent aspect ratio of shapes, and investigates how it interacts with binocular cues to surface slant. One way in which statistical information could give rise to the horizontal– vertical illusion would be through prior assumptions about the distribution of slant. This prior would then be expected to interact with retinal cues to slant. We determined the aspect ratio of stereoscopically viewed ellipses that appeared circular. We show that observers’ judgements of aspect ratio were affected by surface slant, but that the largest image vertical:horizontal aspect ratio that was considered to be a surface with a circular profile was always found for surfaces close to fronto-parallel. This is not consistent with a Bayesian model in which the horizontal–vertical illusion arises from a non-uniform prior proba- bility distribution for slant. Rather, we suggest that assumptions about the slant of surfaces affect appar- ent aspect ratio in a manner that is more heuristic, and partially dissociated from apparent slant.
Type: Journal Article
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Rights: Published in Vision Research by Elsevier; Elsevier believes that individual authors should be able to distribute their accepted author manuscripts for their personal voluntary needs and interests, e.g. posting to their websites or their institution’s repository, e-mailing to colleagues. The Elsevier Policy is as follows: Authors retain the right to use the accepted author manuscript for personal use, internal institutional use and for permitted scholarly posting provided that these are not for purposes of commercial use or systematic distribution. An "accepted author manuscript" is the author’s version of the manuscript of an article that has been accepted for publication and which may include any author-incorporated changes suggested through the processes of submission processing, peer review, and editor-author communications.
Notes: This work was funded by BBSRC Grant BB/C005260/1.
Affiliation: University of St Andrews
University of Stirling
University of Cambridge

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