Concurrent assessment of heart rate discrimination and control

A procedure was devised to investigate discrimination and control of heart rate (HR) concurrently. Eighteen volunteers were divided into two equal groups instructed either to increase or to decrease HR during four experimental sessions. In addition, subjects were required to indicate whenever they thought they were successful during the HR control task by pressing a switch. Activation of the switch automatically enabled the presentation of a feedback tone provided that the HR level at that moment, met a preset criterion of change. The feedback was not available during pre- and post-training testing periods. Responses to bidirectional HR control instructions alone were also investigated. Respiration volume and general movement were recorded throughout. While the group given HR increase instructions improved both their discrimination and control performances, the group instructed to decrease HR did not improve. It is suggested that the optimal procedures for training HR increases and decreases may differ, but that the relationship between discrimination and control posited by the calibration model can accommodate these differences.