Visuoproprioceptive conflict in hand position biases tactile localization on the hand surface.

The location of touch can be represented in a somatotopic reference frame and, combined with proprioceptive information, in an external reference frame. There is evidence that body position influences where individuals feel touch on the skin surface, indicating that proprioceptive information affects tactile localization in a somatotopic reference frame. In conditions with visual and proprioceptive mismatch of body position, where do individuals feel touch on the body? We used the mirror box illusion to address this question. Participants placed 1 hand on each side of a mirror aligned with the body midline, such that the hand reflection in the mirror looked like the hand hidden behind the mirror. The illusion creates a spatial mismatch between the actual hidden hand position and where the participant perceives their hand to be (the mirror image location). Across three experiments, localization judgments on the hidden hand were consistently and systematically biased toward the actual hand position relative to the viewed hand position. These findings provide evidence that proprioceptive estimates of limb position influence tactile localization and are discussed in relation to two models of tactile localization. (PsycInfo Database Record (c) 2021 APA, all rights reserved).