Psychophysiological Differences Between Meditators and Non-meditators During Anticipatory Stress

To further understand the psychophysiology of stress, the autonomic responses of experienced meditators (N=14) and non-meditators (N=14) were compared during Auditory Startle Response and Mental Arithmetic conditions. Meditators and controls motivational preferences were assessed using a Reversal Theory (Apter, 1988) questionnaire. Significant group differences were found where reduced eyeblink amplitudes for meditators, but not reduced eyeblink onset latency, provided partial support for the prediction that meditators would be less anxious than non-meditators. The prediction that meditators would demonstrate overall greater autonomic recovery than non-meditators was not supported, although vagal tone activation showed predicted differences. Questionnaire data supported the prediction that meditators would prefer lower arousal and be more Compliance dominant than non-meditators. Clinical implications of the present study and future directions for research are discussed. 39 Literature reviews have assessed research that compared physiological differences between meditation and relaxation (Dillbeck & Orme-Johnson, 1987), meditation with other self-control strategies (Shapiro, 1982), and the ability of meditation to reduce anxiety (Delmonte, 1985a). Results are equivocal for the efficacy of relaxation and for self-control strategies, and in general meditation is associated with reduced anxiety. A more relevant research question is whether meditation demonstrates unique effects under stressful or threatening conditions compared with controls (Morrell, 1986). Meditation and Autonomic Arousal Reduction Holme's (1984) literature review of meditation and its proposed ability to reduce physiological arousal found no evidence from the four studies he reviewed that meditators could achieve or maintain lower levels of arousal in threatening situations, compared with non-meditating controls. Three of the four studies Holmes reviewed used novice meditators. Shapiro (1982) made the point that conclusions generalised from novices contributed to flawed results in meditation research. The fourth study Holmes reviewed (Goleman & Schwartz, 1976) found experienced Transcendental meditators demonstrated increased physiological responses, heart rate (HR) and skin conductance response (SCR) to a stressor film, compared to non-meditating controls. The significant initial increase in HR reactivity followed by faster SCR habituation and faster recovery time was interpreted as a form of increased adaptive coping. In contrast, Holmes' interpretation was that meditators were not able to reduce somatic arousal under threat, particularly as SCR reduction only brought the meditators down from a high level of arousal to that of non-meditating controls. Morrell (1986) commented that 40 Holmes' dismissal of Goleman and Schwartz's (1976) results ran the risk of overlooking important clinical implications. Other studies have found meditators to have increased arousal under stress conditions (Lehrer, Schoickett, Carrington, & Woolfolk, 1980). The auditory startle response (ASR) has been used to induce anticipatory stress in meditation research. Orme-Johnson (1973) found meditators electrodermal responses habituated to an auditory startle stimuli (100 dB) faster than non-meditating controls, also meditators made fewer multiple electrodermal responses during habituation. The interpretation of results was that meditators may have greater autonomic stability in responding to stress. Lehrer, et al., (1980) found that meditators demonstrated increased HR and Frontalis electromyograph (EMG) activity, more frontal electroencephalograph (EEG) alpha, and fewer cognitive symptoms of cognitive anxiety than either a relaxation or resting control group, during ASR's (100 dB). Results were interpreted as supporting Goleman and Schwartz's (1976) proposal that heightened arousal under threat prepares meditators for stress coping. Anxiety and Startle Response Research Research indicates that anxiety and fear increase the magnitude of the startle response in animals (Brown, Kalish, & Faber, 1951) and humans (Anthony & Graham, 1985). Anticipatory anxiety has been measured objectively using a fear potentiated startle response in a paradigm not requiring any shock (Grillon, Ameli, Woods, Merikangas, & Davis, 1991). Clinical studies indicate that exaggerated ARSs have been associated 41 with current posttraumatic stress disorder, supporting the link between eyeblink amplitude and anxiety (Butler, Braff, Rausch, & Jenkins, 1990; Morgan, Grillon, Southwick, Davis, & Charney, 1996). The eyeblink component of the startle response has the advantage of being faster, more stable, and can be evoked at lower levels than a whole body response (Lang, Bradley, & Cuthbert, 1990). Cardiac Responses and Respiratory Sinus Arrhythmia (RSA) While it is well established that cardiac mechanisms are under dual sympathetic and parasympathetic neural control (Berntson, Cacioppo, & Quigley, 1993), meditation studies investigating stress reactivity have not differentiated these autonomic HR influences (English & Baker, 1983; Goleman & Schwartz, 1976; Heide, 1986; Lehrer et al., 1980). Polyvagal theory proposes that the two pathways of the vagus nerve operate independently and are responsible for divergent shifts in RSA and HR respectively, where an increase in HR will not necessarily be associated with a decrease in RSA (Porges, 1995). RSA measures the rhythmic fluctuations in beat-to-beat HR associated with respiration (Lane, Adcock, & Burnett, 1992), and even when alterations in parasympathetic tone are small, RSA remains sensitive to cardiac vagal tone (Grossman, Stemmler, & Meinhardt, 1990). Mental arithmetic as a laboratory stressor, has been found to simultaneously activate both autonomic branches (Muller, Schandry, Montoya, & Gsellhofer, 1992). 42 Motivation and Reversal Theory For meditation to be of therapeutic use, clinicians need to know when a technique is useful and for which patients (Shapiro, 1982). The motivational characteristics of meditators have received less attention than physiological responses. Since there are large drop-out rates among novices, experienced meditators may constitute a selfselected subgroup with specific motivational characteristics (Delmonte, 1984a). Reversal theory is increasingly being used to explain behaviour, including stress related and health promoting behaviours (Svebak & Apter, 1997). The theory proposes a relationship between metamotivational modes where arousal-seeking/arousal-avoiding behaviour is moderated by 'felt arousal' (high/low). In the arousal-seeking mode a person experiences increases in arousal as increasingly pleasant, or as increasingly unpleasant if in the arousal-avoiding mode, as it increases. Apter (1988) identified somatic emotions that are moderated by 'felt physiological arousal' and transactional emotions that reflect 'felt gain or loss' in response to transactions with people, situations or objects. The first pair of somatic modes are the Telic (goal-oriented, arousalavoiding) and Paratelic (playful/arousal-seeking) modes. Each pair member can be experienced at high or low arousal levels. Any emotion involving high arousal in the telic mode will be unpleasant, whereas in the paratelic mode high arousal will always be experienced as pleasurable. The second pair are the Compliance (agreeable) and Negativistic (rebellious) modes. Metamotivational modes blend to form mode combinations such as telic-compliance where goal-directed behaviour conforms to some external expectation, and is experienced at either high (anxiety) or low arousal levels (relaxation). The first pair of transactional emotions are the Mastery/Sympathy 43 pair. The mastery mode is oriented towards control and winning/losing, whereas the sympathy mode is care-oriented and involves sensitivity. The other transactional pair are the Autic (self-concerned) and Alloic (other-concerned) modes. Transactional modes combine at high/low levels of gain. For example, a low gain autic-mastery transaction (loss) is experienced as humiliation, whereas a high gain transaction (win) is experienced as pride. Each mode pair gives rise to two opposing emotions, resulting in an account of eight pairs of opposing emotions. According to Frey (1997) the majority of people have a dominant state involving preference for combinations of modes to which they are predisposed. Similarly, some emotions are more salient than others and underlie desire, behaviour and thinking. Mode dominance and emotional salience determine motivation, personality and emotional experience. Conclusion Meditation research suggests that meditators heightened physiological arousal under threat better prepares them for stress coping. Polyvagal theory suggests that negative experience such as stress, reduces RSA. Respiratory sinus arrhythmia is a sensitive index of parasympathetic cardiac control that has not previously been used in meditation research. Startle response research suggests eyeblink magnitude and onset latency vary with anticipatory anxiety levels. Based on evidence drawn from meditation research and startle response research it is proposed that meditators will demonstrate lower amplitude and greater latency in response to auditory startle stimuli than nonmeditators. Meditators will demonstrate overall greater ANS recovery from cognitive stress than non-meditators.