Figure 2.
a–c, Subjects' efficiencies in the NN, PN, and IPN conditions, respectively. Efficiency on an individual trial is defined as the ratio of a subject's performance (the amount of time that the object spent in the target region) to the average performance of the ideal actor. Black bars indicate a subject's efficiency during the first 30 trials of a session, whereas gray bars indicate the efficiency during the last 30 trials (error bars give the SEMs). In the NN condition, six of six subjects showed significant improvement in efficiency (two-tailed t test, p < 0.01), in the PN condition, five of six subjects showed significant improvement (p < 0.03), and, in the IPN condition, six of six subjects showed significant improvement (p < 0.03). d, Subjects' average control signals (based on the magnitude of these signals, not their signs) during the first and last 2 s of the final 30 trials (error bars show SEM). e, Typical control strategies during the last 30 trials of randomly selected subjects in the NN, PN, and IPN conditions.