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Abstract
The horizontalvertical illusion, in which the vertical dimension is overestimated relative to the horizontal 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 horizontalvertical 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 frontoparallel. This is not consistent with a Bayesian model in which the horizontalvertical illusion arises from a nonuniform prior probability distribution for slant. Rather, we suggest that assumptions about the slant of surfaces affect apparent aspect ratio in a manner that is more heuristic, and partially dissociated from apparent slant.
Original language  English 

Pages (fromto)  3443 
Number of pages  10 
Journal  Vision Research 
Volume  70 
Early online date  19 Aug 2012 
DOIs  
Publication status  Published  1 Oct 2012 
Keywords
 Horizonalvertical illusion
 Slant
 Binocular disparity
 Aspect Ratio
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Dive into the research topics of 'Misperception of aspect ratio in binocularly viewed surfaces'. Together they form a unique fingerprint.Projects
 1 Finished

BB/C005260/1: Binocular vision and the statistics of binocular disparity
Hibbard, P. B. (PI)
1/01/05 → 31/12/08
Project: Standard