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ERIC Number: EJ934350
Record Type: Journal
Publication Date: 2011-Jun
Pages: 7
Abstractor: As Provided
ISSN: ISSN-0096-1523
Weber's Illusion and Body Shape: Anisotropy of Tactile Size Perception on the Hand
Longo, Matthew R.; Haggard, Patrick
Journal of Experimental Psychology: Human Perception and Performance, v37 n3 p720-726 Jun 2011
The perceived distance between touches on a single skin surface is larger on regions of high tactile sensitivity than those with lower acuity, an effect known as "Weber's illusion". This illusion suggests that tactile size perception involves a representation of the perceived size of body parts preserving characteristics of the somatosensory homunculus. Here, we investigated how body "shape" is coded within this representation by comparing tactile distances presented in different orientations on the hand. Participants judged which of two tactile distances on the dorsum of their left hand felt larger. One distance was aligned with the proximodistal axis ("along" the hand), the other with the mediolateral axis ("across" the hand). Across distances were consistently perceived as larger than along ones. A second experiment showed that this effect is specific to the hairy skin of the hand dorsum and does not occur on glabrous skin of the palm. A third experiment demonstrated that this bias reflects orientation on the hand surface, rather than an eye- or torso-centered reference frame. These results mirror known orientational anisotropies of both tactile acuity and of tactile receptive fields (RFs) of cortical neurons. We suggest that the dorsum of the hand is implicitly represented as wider than it actually is and that the shape of tactile RFs may partly explain distortions of mental body representations. (Contains 4 figures and 1 footnote.)
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Publication Type: Journal Articles; Reports - Evaluative
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A