Precise tactile localisation of hair stimulation in humans

Hair is a salient feature of the bodies of humans and other mammals, which serves a variety of functions, including sensation. The sensory functions of hairs in humans, however, remain poorly understood. This study measured the ability to perceive the spatial location of stimulation of hairs without associated stimulation of the skin. We tested this ability body on the hand (Experiment 1) and the forearm (Experiment 2). Participants judged locations by clicking on a picture of their own hand/arm. We compared tactile localisation performance following hair stimulation to direct stimulation of the skin. Participants showed highly precise localisation of hair stimulation. The precision of localisation of hair stimulation is similar to that of stimulation of the skin. The results of this study show that human hairs provide rich spatial information which may complement tactile signals from the skin itself.