Just seeing you makes me feel better: interpersonal enhancement of touch.

The human brain may contain "mirror systems" allowing mental simulation of the sensorimotor states of others. Most research has focused on interpersonal sharing of motor representations, with relatively little focus on sensation. Here we show that viewing the body of another person significantly enhances the spatial resolution of touch on the corresponding body part. Thirty subjects judged the orientation of gratings presented to the index finger tip, either when viewing their own hand, when viewing a neutral object presented in approximately the same location, or when viewing the undisguised hand of a third person standing behind them. Orientation discrimination was significantly more accurate when viewing one's own body compared to when viewing a neutral object. The same enhancement effect was found when viewing another's body. Performance when viewing one's own body did not differ significantly from performance when viewing the body of another person. This result suggests a purely sensory interpersonal sharing of body representations. It also suggests a specifically interpersonal modulation of primary sensory functions within the brain.