Watching neutral and threatening movies: Subjective experience and autonomic responses in subjects with different hypnotizability levels E.L. Santarcangelo a, ⁎, G. Paoletti a , R. Balocchi b , E. Scattina a , B. Ghelarducci a , M. Varanini b a Department of Physiological Sciences, University of Pisa, Italy b Institute of Clinical Physiology, National Council of Research, Pisa, Italy abstract article info Article history: Received 4 October 2011 Received in revised form 26 December 2011 Accepted 10 January 2012 Available online 25 January 2012 Keywords: Hypnotizability Heart rate Heart rate variability Skin conductance Attention Emotion Subjects with high hypnotizability scores (Highs) have been considered more prone to experience negative affect and more vulnerable to its autonomic effects with respect to low hypnotizable individuals (Lows). The aim of the study was to analyze the subjective experience, tonic skin conductance (SC), respiratory fre- quency (RF), heart rate (HR) and heart rate variability (HRV) of healthy Highs and Lows during a long-lasting, emotionally neutral task (Session R, 46 subjects) and a moderately threatening one (Session T, 35 subjects). At the end of the relaxing Session R, all participants reported an increased relaxation. At the end of the threat- ening Session T, only 20 subjects reported a decreased relaxation (effective T: eT subsample). Highs and Lows of this subsample reported a similarly reduced relaxation and showed a similarly increased skin conductance. HR and HRV did not differ between the two sessions and between Highs and Lows. Among the subjects not reporting decreased relaxation at the end of Session T (ineffective T: iT subsample, n = 15), relaxation was deeper and associated with lower skin conductance in Highs, although HR and HRV did not differ between Highs and Lows. All together, the results do not support the hypothesis of higher proneness of Highs to ex- perience negative affect and to exhibit the autonomic correlates of negative emotion. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Hypnotizability is a cognitive, multidimensional trait related to the ability to accept hypnotic suggestions and is measured by scales (Green et al., 2005). The subjects obtaining high scores at hypnotizability scales (Highs) can behave according to suggestions and report involuntariness in action. In addition, recent evidence concerning sensory-motor integra- tion (Carli et al., 2008; Santarcangelo et al., 2008a, b; Menzocchi et al., 2010; Castellani et al., 2011) has shown that Highs and Lows (low hyp- notizable subjects) may differentially react to cognitive and physical stimulations even in absence of any suggestion and out of hypnosis. It has been claimed that Highs are particularly vulnerable to cogni- tively induced autonomic disease owing to their ability of deep involve- ment in mental images (Tellegen and Atkinson, 1974; Lichtenberg et al., 2004) inducing congruent autonomic patterns (Wickramasekera and Price, 1997). Yet, few studies have been conducted on the effects of cog- nitive/emotional stimulation in not hypnotized Highs and Lows (Harris et al., 1993; Ray et al., 2000, Zachariae and Jorgensen, 2000; Jorgensen and Zachariae, 2002; Sebastiani et al., 2003) and their results are not quite consistent. Most of them were focused on heart rate and on the spectral analysis of heart rate variability (HRV), whose Low (LF) and High (HF) Frequency components reflect the sympathetic and parasympathetic control of heart rate, respectively (Task Force, 1996). One of the studies showed that subjects with lower heart rate during baseline and greater heart rate increases during mood induction are more susceptible to hypnosis, and that approximately 40% of the vari- ability of hypnotic susceptibility can be accounted for by baseline cardi- ac vagal tone and heart rate reactivity during mood state (Harris et al., 1993). Other authors reported that hypnotic susceptibility in itself is not associated with peculiar aspects of either basal cardiac states or car- diac responses to cognitive stress (Ray et al., 2000; Zachariae and Jorgensen, 2000; Jorgensen and Zachariae, 2002), and that the auto- nomic response to psychological stressors seems to be predicted better by “absorption”– the involvement in one's own mental images (Tellegen and Atkinson, 1974) – than by hypnotizability (Zachariae and Jorgensen, 2000). In other experiments, during cognitive/emotional tasks both Highs and Lows exhibited a lower decrease of the absolute values of the respiratory-related component of heart rate variability with respect to medium hypnotizable individuals (Jorgensen and Zachariae, 2002). Nevertheless, the latter study did not report any sig- nificant hypnotizability-related difference in the normalized powers of the HRV components (HFn, LFn), that is HF and LF divided by their sum. Interestingly, Jorgensen and Zachariae (2002) found smaller in- creases in skin conductance levels in Highs than in medium and low hypnotizables during cognitive/emotional tasks, which is in line with their observation that Highs tend to underreport and Lows to overre- port the experienced stress. Finally, in a study focused on the guided im- agery of moderately unpleasant, fear-like scenes (Sebastiani et al., International Journal of Psychophysiology 84 (2012) 59–64 ⁎ Corresponding author at: Department of Physiological Sciences, University of Pisa, Via San Zeno, 31-56127 Pisa, Italy. Tel.: +39 050 2213465; fax: +39 050 2213527. E-mail address: enricals@dfb.unipi.it (E.L. Santarcangelo). 0167-8760/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.ijpsycho.2012.01.010 Contents lists available at SciVerse ScienceDirect International Journal of Psychophysiology journal homepage: www.elsevier.com/locate/ijpsycho