Heart rate dynamics in subjects with different hypnotizability

Spectral analysis has been the principal technique used for investigating hypnotizability-related differences in heart rate variability. In contrast to this classical approach, the present study is based on recurrence quantification analysis (RQA), a non-linear method able to describe different features of heart rate dynamics. RQA was used to analyse heart rate data taken from 17 not hypnotized, highly hypnotizable (highs) and 17 low hypnotizable subjects (lows). The data were recorded while the subjects were paying attention to a non-emotional movie. Results showed higher absorption scores (TAS) in highs than in lows, only among males, higher attention to the movie in females, and no correlation between TAS and reported attention. Traditional spectral analysis was able only to reveal gender, but not hypnotizability-related differences in these data. RQA indices also detected gender, but not hypnotizability-related differences in the predictability of heart rate dynamics, and confirmed the parasympathetic prevalence observed in females through spectral analysis. Moreover, some RQA indices were modulated by present attention and not by absorption, changes that were not detected using spectral analysis. Thus, RQA of heart rate dynamics appears to be a useful tool for characterizing individual cognitive states. © 2014 British Society of Clinical and Academic Hypnosis.