Smartphone-enabled pulse rate variability: An alternative methodology for the collection of heart rate variability in psychophysiological research

• Published in: International journal of psychophysiology 2013-09, Vol.89 (3), p.297-304
• Main Author: Heathers, James A.J.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Attention; Electrocardiography; Exercise - physiology; Female; Heart Rate - physiology; Heart rate variability; Humans; Inhibition (Psychology); Internet; Male; Neuropsychological Tests; Photoplethysmography; Psychophysiology; Pulse transit time; Reaction Time - physiology; Rest - physiology; Smartphone; Spectrum Analysis; Young Adult
• ISSN: 0167-8760; 1872-7697
• DOI: 10.1016/j.ijpsycho.2013.05.017

Heart rate variability (HRV) is widely used to assess autonomic nervous system (ANS) function. It is traditionally collected from a dedicated laboratory electrocardiograph (ECG). This presents a barrier to collecting the large samples necessary to maintain the statistical power of between-subject psychophysiological comparisons. An alternative to ECG involves an optical pulse sensor or photoplethysmograph run from a smartphone or similar portable device: smartphone pulse rate variability (SPRV). Experiment 1 determined the simultaneous accuracy between ECG and SPRV systems in n=10 participants at rest. Raw SPRV values showed a consistent positive bias, which was successfully attenuated with correction. Experiment 2 tested an additional n=10 participants at rest, during attentional load, and during mild stress (exercise). Accuracy was maintained, but slightly attenuated during exercise. The best correction method maintained an accuracy of +/−2% for low-frequency spectral power, and +/−5% for high-frequency spectral power over all points. Thus, the SPRV system records a pulse-to-pulse approximation of an ECG-derived heart rate series that is sufficiently accurate to perform time- and frequency-domain analysis of its variability, as well as accurately reflecting change in autonomic output provided by typical psychophysiological stimuli. This represents a novel method by which an accurate approximation of HRV may be collected for large-sample or naturalistic cardiac psychophysiological research. •This work develops an accurate platform for the mass collection of heart rate.•The accuracy of this monitor was tested at rest and during experimental stress.•The monitor returns acceptable raw values which are improved by correction.•Margin of error is smaller than ≈5% for all heart rate variability measures.•This has the potential to greatly increase HRV data collection capacity.