Individual differences in visual imaging and the voluntary control of heart rate.

The role of visual imagery in the bidirectional control of heart rate (HR) was explored in 24 subjects. While voluntary HR increases were reliably demonstrated with and without HR feedback, appropriate HR decreases were modest and inconsistent. Changes in respiration rate (RR) generally paralleled the alterations in HR. Eighteen of the subjects reported conventionally using visual imagery to effect HR changes. For these subjects, vividness of visual imagery scores and the extent of HR change showed indications of a direct relationship in the HR increase condition. However, in the HR decrease condition, it was concomitant RR changes which were associated with the vividness and the control of imagery production. The remaining six subjects, who reported not employing visual imagery, demonstrated superior HR acceleration to the imaging subjects. Further, while the imaging subjects did not benefit from the introduction of feedback, the six non-imaging subjects showed reliably greater HR acceleration as a result of feedback introduction.