Abstract:
Four experiments were done to examine bi-directional control of heart rate using visual transformations of the heart beat as feedback reinforcement. Experiment 1 compared binary feedback from a success signal light with proportional feedback from a meter which showed changes in heart rate as deflections of a pointer. Findings confirmed and extended earlier work showing that proportional feedback exerts greater control of heart rate increase and heart rate decrease. The experiment also examined retention of heart rate control after feedback is withdrawn. In accord with earlier work there was no immediate decrement in performance on removal of feedback. Earlier work inferred from this effect that control is maintained in the no-feedback condition. In Experiment 1, however, control declined rapidly over four no feedback sessions. The process resembled operant extinction. Experiment 2 compared repeated instructions to control heart rate and practice over extended sessions with instructions plus proportional visual feedback. The addition of feedback reliably augmented control. Respiratory involvement during heart rate increase trials attenuated over sessions yet control was progressively enhanced. Experiment 3 examined long-term retention of heart rate control and the application of a generalisation procedure, namely the finger-felt wrist pulse. Control of heart rate progressively declined on retesting in a no-feedback or wrist-pulse feedback situation after seven months and after 16 months following acquisition. Wrist-pulse feedback did not assist in generalisation of heart rate control. Again the process resembled operant extinction. Experiment 4 compared continued feedback with wrist-pulse feedback and interpolated feedback over generalisation and retention sessions. After acquisition, the wrist-pulse feedback group progressively lost control over generalisation and retention in a curve resembling operant extinction. The interpolated feedback group maintained control over generalisation sessions containing progressively more no-feedback trials, a finding resembling the partial reinforcement effect. The interpolated feedback group also maintained substantial control over no-feedback retention sessions. The problem of what stimuli might be involved in this apparent generalisation is unanswerable from this research. The continued feedback group lost control rapidly over no feedback retention sessions in a way resembling operant extinction. After controlling for instructions, respiration and muscular mediation, it was inferred that the feedback used was effective for bi-directional control of heart rate. Large scale bi-directional control (>10 bpm) was found in all experiments for all feedback groups, even after subtraction of initial control to instructions alone. It was concluded that the bi-directional control achieved and the extinction-like and generalisation-like changes in the conditioned heart rate response are consistent with an operant conditioning model of visceral control.