Criterion level and instructional effects in the voluntary control of heart rate.

Two experiments are reported. In experiment 1 the effects of different punishment criteria on the acquisition of voluntary control of heart rate was studied in three groups of 10 subjects. Punishment criterion was manipulated so that the 10, 30 and 50% most extreme interbeat intervals in the opposite direction from the desired heart rate change were punished. Subjects received four training sessions, two directed at increasing heart rate, and two at decreasing. Substantial bidirectional heart rate changes were obtained very early in training. Some weak evidence of criterion effects was obtained. In a supplementary experiment modelled on experiment 1, the instructions plus feedback used in experiment 1 were compared with instructions alone. Feedback did not aid heart rate control. In both experiments there was evidence of skeletal involvement in the heart rate change.