Shrinkage in the Apparent Size of Cylindrical Objects

A novel illusion in apparent size is reported. We asked observers to estimate the width and depth of vertically oriented elliptic cylinders depicted with texture or luminance gradients (experiment 1), or the height of horizontally oriented elliptic cylinders depicted with binocular disparity (experiment 2). The estimated width or height of cylinders showed systematic shrinkage in the direction of the gradual depth change. The dissimilarity of 2-D appearance amongst our stimuli implies a large variation in spatial-frequency components and brightness contrasts, eliminating the possibility that these parameters contributed to the illusion. Also, the mechanism inappropriately triggered by pictorial depth cues (eg size scaling) may be irrelevant, because the illusion was obtained even when binocular disparity alone specified the shape of the cylinders. The illusion demonstrated here suggests that our visual system may determine the size of 3-D objects by accounting for their depth structures.

[1]  T. A. Ryan,et al.  Significance tests for multiple comparison of proportions, variances, and other statistics. , 1960, Psychological bulletin.

[2]  J. P. Harris,et al.  Illusion-Destruction by Appropriate Scaling , 1975 .

[3]  S. Nakamizo,et al.  Evidence for the Correcting-Mechanism Explanation of the Kanizsa Amodal Shrinkage , 2005, Perception.

[4]  T. Oyama.  Japanese studies on the so-called geometrical-optical illusions. , 1960 .

[5]  R. Gregory.  Eye and Brain: The Psychology of Seeing , 1966 .

[6]  R. Gregory,et al.  Distortion of Visual Space as Inappropriate Constancy Scaling , 1963, Nature.

[7]  J T Todd,et al.  The Discriminability of Local Surface Structure , 1996, Perception.

[8]  F S Frome,et al.  Shifts in perception of size after adaptation to gratings. , 1979, Science.

[9]  Sakuichi Ohtsuka,et al.  Correct 3-D but illusory 2-D percepts linked to binocularly unpaired regions , 2002, SPIE ITCom.

[10]  R. W. Ditchburn.  Seeing is Deceiving: The Psychology of Visual Illusions , 1979 .

[11]  Apparent size and receptive field properties , 1988, Vision Research.

[12]  A. Parker,et al.  Effects of different texture cues on curved surfaces viewed stereoscopically , 1993, Vision Research.

[13]  M. Murtagh,et al.  Task and size effects in the Oppel-Kundt and Irradiation illusions. , 1984, The Journal of general psychology.

[14]  J. Todd,et al.  Perception of three-dimensional form from patterns of optical texture. , 1987, Journal of experimental psychology. Human perception and performance.

[15]  Hugh R. Wilson,et al.  Shifts in perceived size as a function of contrast and temporal modulation , 1983, Vision Research.