PRINCIPLES FOR LEARNING SINGLE-JOINT MOVEMENTS .2. GENERALIZING A LEARNED BEHAVIOR

The previous paper in this series showed that changes both within and between experimental sessions can be understood in the framework of th e dual-strategy hypothesis of motor control, with a modification somet imes required for the timing of the antagonist muscle. The present pap er extends these findings by determining how practicing movements at o ne distance generalizes to changes in performance at other distances. Five subjects made elbow flexion movements over five different distanc es (pretest). They then performed 1400 movements (seven sessions of te n blocks of 20 trials) at only one of those distances. The subjects th en repeated the flexion movements over the five different distances (p osttest). On the posttest, subjects decreased their average movement t ime by 20 ms. In addition, their movements became less variable. The e lectromyographic pattern of the faster movements was characterized by a more rapidly rising electromyogram, for three of the subjects, and a n antagonist latency that decreased.