Relative Wnger position inXuences whether you can localize tactile stimuli

To investigate whether the relative positions of the Wngers inXuence tactile localization, participants were asked to localize tactile stimuli applied to their Wngertips. We measured the location and rate of errors for three Wnger conWgurations: Wngers stretched out and together so that they are touching each other, Wngers stretched out and spread apart maximally and Wngers stretched out with the two hands on top of each other so that the Wngers are interwoven. When the Wngers contact each other, it is likely that the error rate to the adjacent Wngers will be higher than when the Wngers are spread apart. In particular, we reasoned that localization would probably improve when the Wngers are spread. We aimed at assessing whether such adjacency was measured in external coordinates (taking proprioception into account) or on the body (in skin coordinates). The results conWrmed that the error rate was lower when the Wngers were spread. However, there was no decrease in error rate to neighbouring Wngertips in the Wngers spread condition in comparison with the Wngers together condition. In an additional experiment, we showed that the lower error rate when the Wngers were spread was not related to the continuous tactile input from the neighbouring Wngers when the Wngers were together. The current results suggest that information from proprioception is taken into account in perceiving the location of a stimulus on one of the Wngertips.