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Abstract

Stored representations of body size and shape as derived from somatosensation are considered to be critical components of perception and action. Recent research has shown the presence of large hand distortions in proprioceptive localization tasks consisting of an overestimation of hand width and an underestimation of finger length. Those results were interpreted as reflecting specific somatosensory perceptual distortion bound to a body model underlying position sense. One important prerequisite to this interpretation is that measured localization task distortions actually stem from body representation. In this study, we re-examine hand distortions underlying positon sense and investigate whether these distortions are body specific or due to non-perceptual factors, e.g. conceptual knowledge. Participants made localization judgments regarding the spatial position of various landmarks on occluded items including their own hand. Our results show that larger hand distortions in localization tasks are likely to be induced by participants' incorrect conceptual knowledge about hand landmarks rather than proprioceptive or somatosensory influences. Moreover, we show that once we account for such incorrect conceptual knowledge, hand distortions in localization tasks are statistically similar to those of other objects. These results suggest that localization task distortions are not specific to the hand and call for caution when interpreting localization task distortions in terms of body specific effects.