Illusory Shrinkage and Growth: Body-Based Rescaling Affects the Perception of Size

Department of Psychology, University of Virginia, 102 Gilmer Hall, Charlottesville, VA 22904, USA.
Psychological Science (Impact Factor: 4.43). 09/2010; 21(9):1318-25. DOI: 10.1177/0956797610380700
Source: PubMed


The notion that apparent sizes are perceived relative to the size of one's body is supported through the discovery of a new visual illusion. When graspable objects are magnified by magnifying goggles, they appear to shrink back to near-normal size when one's hand (also magnified) is placed next to them. When objects are "minified" by minifying goggles, the opposite occurs. The rescaling effect also occurred when participants who were trained in tool use viewed the tool next to the objects. However, this change in apparent size does not occur when familiar objects or someone else's hand is placed next to the magnified or minified object. Presumably, objects' apparent sizes shift closer to their actual sizes when one's hand is viewed because objects' sizes relative to the hand are the same with or without the goggles. These findings highlight the role of body scaling in size perception.

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Available from: Dennis R. Proffitt, Jun 18, 2014
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    • "Until recently, the methods that came closest to this requirement altered the apparent size of one’s hand either by zooming in and out on video-recorded displays (Marino, Stucchi, Nava, Haggard, & Maravita, 2010; Pavani & Zampini, 2007) or by using magnifying and minifying goggles (Linkenauger, Ramenzoni, & Proffitt, 2010). It has been shown that such visual distortion of the hand affects both the hand shape during object grasping (Marino et al., 2010) and size perception as measured by a size-matching task (Linkenauger et al., 2010). Interestingly, the latter study found that someone else’s hand does not induce this effect, which suggests that one’s own body or, at least, one’s own hand plays a special role in calibrating size perception. "
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    • "For each subject, we calculated the mean probability of reporting the distance on the upper arm as longer for all combinations of inter-point distances (P-Arm). We predicted that P-Arm would vary depending on the perceived size of the stimulated arm, in line with a context dependent bias, well documented in the field of visual perception [e.g.2930], and suggested also for haptic exploration [e.g.31; but see also32 for a different interpretation] and recently confirmed also for a visual3334 and a tactile distance perception task34. According to this bias, higher or lower P-Arm would indicate, respectively, that the upper arm is perceived as shorter or as longer. "
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    • "Following principles of ecological psychology and embodied perception in experimental psychology, recent research has further revealed that own-body representations may influence how an observer perceives an environment (Gibson, 1979; Neisser, 1988). It has thus been demonstrated that perceived lengths in a visually presented environment might be influenced by the seen scale of one's own body within such an environment (Witt et al., 2005; Linkenauger et al., 2010). Moreover, such altered own-body perceptions seem to be modulated by experimentally induced changes in body ownership (van der Hoort et al., 2011). "
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