Submission 683
Virtual Reality Hand Posture Eliminates the Crossed-Hands Deficit in Tactile Localization
Posterwall-08
Presented by: Elena Azanon
The integration of somatotopic and external spatial representations is fundamental for localizing tactile stimuli. When the hands are crossed, tactile temporal order judgments (TOJ) are typically impaired, reflecting a conflict between anatomical and external reference frames. Prior research demonstrates that this crossed-hands deficit can be modulated by visual information about limb posture, provided this information is embodied and temporally coupled with the observer’s own movements. In the present virtual reality study, participants performed tactile TOJ tasks under four conditions that independently manipulated real arm posture (crossed vs. uncrossed) and the posture of a pair of visuomotor-correlated virtual arms and hands (crossed vs. uncrossed). Replicating classic findings, the crossed-hands posture led to a robust deficit when visual input matched this configuration. Critically, however, the deficit was completely abolished when participants viewed uncrossed virtual limbs that moved in temporal synchrony with their real movements, despite their actual posture being crossed. Conversely, uncrossed arms showed a marked impairment when paired with crossed virtual limbs, approaching the magnitude of the classic crossed-hands deficit. These results demonstrate that visuomotor embodiment of limb posture can override proprioceptive signals in tactile remapping. The findings indicate that the brain flexibly prioritizes visual body configuration when establishing spatial coordinates for touch, and that this weighting is sufficient to fully realign tactile perception even under somatically conflicting conditions.