Ultra-short term heart rate variability as a tool to assess changes in valence.

Heart rate variability (HRV) is an index that has been extensively used in fields such as clinical cardiology, psychiatry, and psychology to assess affective experiences. Although traditionally The European Society of Cardiology and The North American Society of Pacing and Electrophysiology recommended to use either a recording length of 24-h (long-term) or five minutes (short-term), recent advances in the field have suggested the use of ultra-short term (<5 min) HRV measurements. In this study, we investigated whether ultra-short term HRV measurements can be used to investigate the temporal dynamics of experimentally induced emotions using pictures from the International Affective Picture System. We took electrocardiogram recordings from thirty-nine participants, and analyzed the root mean square of the successive differences of the R-R interval using a thirty-second moving window. No significant differences in HRV during positive and negative emotion induction were found. These results call into question the use of ultra-short term HRV as a tool for psychologists to measure changes in valence in affective studies.