Heart rate control and aversive stimulation

College students were required to train heart rate control (heart rate increase and decrease) with visual feedback for three sessions in a within-person design. In the second and third sessions a test period was added when electric shocks were delivered during half in the trials. Subjects had been grouped in advance in an Aware and an Unaware group on the basis of the Automatic Perception Questionnaire (APQ). The results contradicted some findings by other authors which claim that biofeedback can be used to ameliorate subjective effects of aversive stimulation. Alternative interpretations of the discrepant findings were discussed in terms of expectancy effects that may influence autonomically Aware subjects more strongly than Unaware subjects.