Differentiating self-touch from social touch

Humans need to be able to differentiate between signals they produce themselves and signals that arise from non-self-causes. It has long been discussed that the brain uses a copy of the motor command, an efference copy, to predict the sensory outcomes of one’s own action — and to attenuate these. While studies in humans suggest that cerebellum and supplementary motor area play crucial roles in the attenuation, a study in mice suggests a global suppression during self-touch. However, the sensory percepts of self-touch are not fully cancelled out. Humans touch themselves frequently suggesting a behavioral relevance of self-touch, as to refocus attention, to calm oneself down during stress, to itch or for self-enjoyment. We discuss studies on sensory attenuation as well as the behavioral relevance of self-touch and open questions for future research.