Heart rate variability and skin conductance biofeedback: A triple-blind randomized controlled study

High heart rate variability (HRV) and low skin conductance level (SCL) have been associated with low levels of stress. Biofeedback - providing an individual with online information about his or her own physiological state – may help to change these signals in the desired direction and herewith improve an individual’s physical or mental condition. While there is an abundance of biofeedback tools and therapies commercially available, there is a lack of well-controlled validation studies. We here compare changes in several physiological, affective and cognitive variables after administering either a fake or a genuine biofeedback protocol that was aimed at affecting HRV and SCL. Which participants belonged to the genuine biofeedback group and which participants belonged to the control group remained unknown to everyone involved in the study until the very last stage of analysis. We did not find any differences in treatment effect between the two groups of participants. We also did not find correlations between HRV and the physiological, affective and cognitive variables that we measured, but there was some indication of SCL being related to error percentage in a cognitive task. While our study can only show that the studied protocol is not effective on the selected effect measures for the studied group of participants, it adds to the doubt that biofeedback is effective above and beyond non-specific treatment effects.