“…Studies of muscle-action potential (MAP) have shown that several conditions of goal-directed activity increase its amplitude: (a) the duration of the task (Bartoshuk, 1955;Davis, 1937;Smith, 1953;Stennett, 1957); (b) increasing nearness of the goal or of the end of the task (Bartoshuk, 1955;Davis, 1937;Malmo, Shagass, & Davis, 1951;Smith, 1953); (c) the difficulty of the task (Belanger, 1957;Davis, 1938;Shaw & Kline, 1947;Surwillo, 1956); (d) the presence of distracting stimuli (Davis, 1937); (e) the value of the incentive offered to 5 (Surwillo, 1956); (/) the intelligence of S (Shaw & Kline, 1947); and (g) a previous failure, rather than a success, by 5 (Klein, 1951;Leshner, 1961). The latter occurs with task-oriented 5s but not with ego-oriented ones (Reuder, 1956).…”