Proprioceptive Discrimination of a Covert Operant without Its Observation by the Subject

Science  01 Mar 1963:
Vol. 139, Issue 3557, pp. 834-835
DOI: 10.1126/science.139.3557.834


When the subject occasionally emitted an invisibly small thumb twitch (detected electromyographically), he received a tone as a signal to press a key. After several conditioning sessions, the tone was progressively diminished to zero. The subject nevertheless continued to press the key whenever he emitted a thumb twitch, and he reported that he still heard the tone.