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Timothy Vickery, Marvin Chun; Warped spatial perception within and near objects. Journal of Vision 2010;10(7):1186. doi: 10.1167/10.7.1186.
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© ARVO (1962-2015); The Authors (2016-present)
We report that spatial perception is systematically distorted in the space in and around objects. Two dots placed inside a rectangular object's boundaries appeared farther apart than two equivalently spaced dots placed outside of the object. We measured this expansion effect by placing reference dots in one corner of a monitor (either inside an object or without an object present), and asking participants to match the spacing of dots in the opposite corner. In four different experiments, we found significant distortions of spatial distance judgment for reference dots inside objects compared to outside, ranging up to 15% greater in a rectangular object in one experiment (N=20). To test whether this effect is modulated by the strength of perceived organization, we compared the magnitude of illusory expansion across 1.) separated portions of a partially occluded rectangle compared with separated objects; 2.) within an illusory Kanizsa square compared to when the inducers were rotated 180 degrees; and 3.) within a single rectangle compared with two separate rectangles. In all three cases, the strong-structure conditions (the occluded rectangle, illusory square, and single object) showed a significantly greater expansion than weaker-structure conditions. This illusion could not be explained by a simple depth-based account, which would predict perceived contraction of space in the region occluding an object. However, the illusion did reverse to a contraction effect for dot spacings that were near the edges of the objects and larger than the object. In conclusion, space is systematically distorted by perceived structure. We propose that the allocation of attention to the surface of a selected object may result in distortions in spatial perception.
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