The categorical perception of tactile distance: a difference in acuity at anatomical landmarks?
Le Cornu Knight, F. and Bremner, A.J. and Longo, Matthew R. (2012) The categorical perception of tactile distance: a difference in acuity at anatomical landmarks? Seeing and Perceiving 25 , p. 42. ISSN 1878-4755.
Tactile distance judgments are prone to a number of physiological and perceptual distortions. One such distortion concerns tactile distances over the wrist being perceptually elongated relative to those within the hand or arm. This has been interpreted as a categorical segmentation effect: The wrist implicitly serves as a partition between two body part categories so that stimuli crossing the wrist appear further apart. The effect could alternatively be explained in terms of specialized acuity at anatomical landmarks (i.e., the wrist). To test these opposing explanations we presented participants with two tactile distances sequentially for comparison (one mediolaterally, across the arm, and the other proximodistally, along the arm). Points-of-Subjective-Equality (DV) were compared on the hand, wrist and arm, on dorsal and ventral surfaces between subjects. If the acuity account were true distances would be elongated in both axes at the wrist. If the categorical segmentation account were true there would be a selective perceived increase of the proximodistal distance at the wrist. A previously reported mediolateral bias was found on all body parts but, consistent with the categorical account, at the wrist the magnitude of the bias was either reduced (dorsally) or not found (ventrally) suggesting a selective proximodistal elongation. We found no evidence of increased acuity in the vicinity of the wrist in this task. Therefore we conclude that the segmentation of the body into discrete parts induces categorical perception of tactile distance.
|Keyword(s) / Subject(s):||body representation, categorical perception, acuity, Tactile perception|
|School:||Birkbeck Schools and Departments > School of Science > Psychological Sciences|
|Research Centre:||Brain and Cognitive Development, Centre for (CBCD)|
|Date Deposited:||29 Jan 2014 14:38|
|Last Modified:||02 Dec 2016 11:52|
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