A "mind-reading" technique, muscle reading depends on careful attention to involuntary muscle movement. A blindfolded percipient interprets the pressure of a subject's hand on his shoulder as he approaches an object silently thought of in advance by the subject, whereas an unbound percipient watches the subject's face for unintentional signals indicating whether he has made a correct guess. Muscle reading is not considered a psychic ability but a parlor trick that can be picked up with sufficient practice.