Categorical perception of tactile distance

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Le Cornu Knight, Frances; Longo, M. R. and Bremner, Andrew J.. 2014. Categorical perception of tactile distance. Cognition, 131(2), pp. 254-262. ISSN 0010-0277 [Article]

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Abstract or Description

The tactile surface forms a continuous sheet covering the body. And yet, the perceived distance between two touches varies across stimulation sites. Perceived tactile distance is larger when stimuli cross over the wrist, compared to when both fall on either the hand or the forearm. This effect could reflect a categorical distortion of tactile space across body-part boundaries (in which stimuli crossing the wrist boundary are perceptually elongated) or may simply reflect a localised increased in acuity surrounding anatomical landmarks (in which stimuli near the wrist are perceptually elongated). We tested these two interpretations across two experiments, by comparing a well-documented bias to perceive mediolateral tactile distances across the forearm/hand as larger than proximodistal ones along the forearm/hand at three different sites (hand, wrist, and forearm). According to the ‘categorical’ interpretation, tactile distances should be elongated selectively in the proximodistal axis thus reducing the anisotropy. According to the ‘localised acuity’ interpretation, distances will be perceptually elongated in the vicinity of the wrist regardless of orientation, leading to increased overall size without affecting anisotropy. Consistent with the categorical account, we found a reduction in the magnitude of anisotropy at the wrist, with no evidence of a corresponding localised increase in precision. These findings demonstrate that we reference touch to a representation of the body that is categorically segmented into discrete parts, which consequently influences the perception of tactile distance.

Item Type:

Article

Identification Number (DOI):

https://doi.org/10.1016/j.cognition.2014.01.005

Additional Information:

This research was supported by an award from the European Research Council under the European Community’s Seventh Framework Programme (FP7/2007-2013) (ERC Grant Agreement No. 241242) to AJB.

Keywords:

Self perception; Body representation; Tactile perception; Categorical perception; Tactile acuity

Departments, Centres and Research Units:

Psychology

Dates: