Article

Is there an interaction between perceived direction and perceived aspect ratio in stereoscopic vision?

Attention Perception & Psychophysics (Impact Factor: 2.15). 04/2012; 62(5):910-926. DOI: 10.3758/BF03212077

ABSTRACT In monocular vision, the horizontal/vertical aspect ratio (shape) of a frontoparallel rectangle can be based on the comparison
of the perceived directions of the rectangle’s edges. In binocular vision of a typical three-dimensional scene (when occlusions
are present), this is not the case: Frontoparallel rectangles would be perceived in a distorted fashion if an observer were
to base perceived aspect ratio on the perceived directions of the rectangle’s edges. We psychophysical^ investigated stereoscopically
perceived aspect ratios of frontoparallel occluding and occluded rectangles for various distances and fixation depths. We
found that observers did not perceive the distortions that would be predicted on the basis of the above-mentioned comparison
of the perceived visual directions of the edges of the rectangle. Our results strongly suggest that the mechanism that determines
perceived aspect ratio is dis-sociated from the mechanism that determines perceived direction. The consequences of the findings
for the Kanizsa, Poggendorff, and horizontal/vertical illusions are discussed.

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