The spacing illusion: a spatial aperture problem?

Mather, George, O'Halloran, A. and Anstis, Stuart (1991) The spacing illusion: a spatial aperture problem? Perception, 20 (3). pp. 387-392. ISSN 0301-0066

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Item Type:Article
Item Status:Live Archive


A geometrical illusion in which the horizontal spacing between adjacent parallel lines in a row is underestimated when the lines are tilted away from vertical in a chevron configuration was investigated in two experiments. The perceived spacing was found to decrease as the tilt angle increased, consistent with the idea that separation judgements are influenced by the normal spacing between lines ie at right angles to the line orientation. It is proposed that this illusion reveals an analogue in spatial perception to the well-known aperture problem in motion perception. In establishing the separation of nearby or overlapping shapes in an image, the visual system cannot only rely upon the normal separation of contours belonging to each shape (as would be visible through small spatial apertures or receptive fields), since this varies with contour orientation. The system is therefore faced with a spatial aperture problem. The spacing illusion may arise because information usually available to solve the problem is absent in the illusion figure, or it may reflect a bias in favour of the orthogonal, which is adopted in the face of the ambiguity.

Keywords:adult, article, attention, depth perception, discrimination learning, distance perception, female, human, male, orientation, psychophysics, visual illusion, Adult, Optical Illusions, Space Perception, Support, Non-U.S. Gov't
Subjects:B Subjects allied to Medicine > B140 Neuroscience
C Biological Sciences > C830 Experimental Psychology
Divisions:College of Social Science > School of Psychology
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ID Code:16135
Deposited On:03 Dec 2014 16:33

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