Three experiments are reported comparing different biofeedback displays in a heart rate speeding task. The first experiment examined the effects of heart rate feedback presented at three frequencies in a fixed-time format. Information was given at 0.5-sec, 2-sec and 8-sec intervals. Results indicated that both the 0.5-sec and 8-sec groups' speeding performances were superior to that of the 2-sec group. The second experiment compared a 1-sec fixed-time group with groups receiving displays in which feedback was presented synchronously with systole. Feedback was synchronized either with every heart beat or every tenth beat. The one-beat group was superior to both the 1-sec and 10-beat groups. Experiment III again presented displays which terminated with every beat or every tenth beat. However, in the previous experiment heart interval information was presented only briefly at the systole ending the sample period. In Experiment III, criterion terminations remained on the feedback screen throughout the subsequent interval. Thus, subjects did not have the additional task of attending to very briefly presented information. Nevertheless, speeding performances of the one-beat group were again superior to that attained by the 10-beat group. In all experiments a relationship between increased respiratory and skin conductance levels and heart rate speeding performances was found, suggesting that heart rate speeding was part of a generalized pattern of arousal. It was concluded that instructed heart rate speeding is highly sensitive to changes both in the frequency of feedback presentation, and to the type of display (fixed-time or heart-time) presented.