Meditation is generally defined as a class of techniques designed to influence an individual's consciousness through the regulation of attention. However, there is less agreement on its conceptualization than is commonly thought. Necessary procedural elements seem to be: (1) to lie quietly or to sit in a particular position, (2) to attend to one's breathing but not necessarily to try to slow it, (3) to adopt a passive attitude, (4) to be at ease, and, sometimes, (5) to repeat aloud or to oneself a word or phrase, referred to as a mantra. What is less clear is whether one's mind should be directed to an idea of a Supreme Being or to a less theistic notion of the universality of existence, or whether the mind should be “empty,” except perhaps for the repetition of the mantra. An additional controversy is whether the practice of meditation has to be but one part of a particular life-style, as was and is the case on the Indian subcontinent, where yogic practices and philosophies originated.
One of the problems in evaluating the importance of an overall life-style is that those who are well practiced in meditation (of whatever kind, except perhaps for Westernized versions; see below) are generally the ones who serve as subjects in experiments. Perhaps that is as it should be, given that considerable dedicated practice is asserted to be necessary for doing it “right”; however, that characteristic makes it difficult to separate specific techniques from a firmly held belief system. In this respect, research on meditation is similar to research on such topics as psychoanalysis and related approaches to clinical treatment.
There are three streams in the history of meditation. First, meditation is central to various forms of eastern mysticism, especially Buddhism,
the central principle of which is that God is knowable through proper meditation. An insight unknowable except to the faithful can also lead to greater physical strength, long life, and a general contentment (“Nirvana”). The proper practice of meditation, however, is said to require a withdrawal from the everyday world, although the dramatic experience of Buddhist Vietnamese monks immolating themselves with fire as a political protest in the early 1970s indicates that such priestly withdrawal is not incompatible with deep concern for everyday realities.
Second, in the late 1950s a wise man from India known as the Maharishi Mahesh Yogi introduced transcendental meditation to the West, especially the United States. The Maharishi stated that transcendental meditation was a method based on scientific principles that could be studied systematically, and that its conscientious practice could lead to a deep and complete understanding of nature and to general benefits for humankind (Maharishi Mahesh Yogi, 1966). Unlike Buddhist meditation, transcendental meditation did not require radical life-style changes or extended practice, and it placed greater emphasis on “destressing ” people than it did on spiritual enlightenment or contact with a Supreme Being. The 1960s was conducive to the spread of transcendental meditation among both lay people and scientists; the work of the latter group is reviewed below.
A third stream in humankind's long-standing interest in meditation can be found in some Western mystical traditions, both Christian and Jewish. Among Hasidic Jews, for example, there is a tradition of dancing and chanting for long periods of time in order to achieve an altered state in which the teachings of God can be more readily received.
Thus, people in many parts of the world have for centuries been drawn to practices that, without drugs or other direct physical manipulations, are believed to lead to altered states of consciousness. These practices are also believed by some to put one in contact with higher truths or with God, and sometimes to bring more earthly benefits, such as better physical and emotional well-being.
SCIENTIFIC EVALUATIONS OF MEDITATION
Divine or spiritual revelation represents one time-honored way to know one's world and one's place in it. It is different from scientific ways of knowing, however, and it is the latter epistemology that guides our evaluation of meditation. Over the past 30 years considerable scientific attention has been directed to various meditative practices.
From a rational point of view, the practice of meditation may lead to psychological and physical benefits by distracting a person from stressors, whether they are environmental or self-generated. (There is a
school of thought that an external event is a stressor only if it is appraised or evaluated as such; see Lazarus, 1966.) If a person seeks out a quiet place, closes his or her eyes, and repeats a mantra, there is every reason to expect that the person's cognitive apparatus will become less occupied with processing negative information. Generations of insomniacs have been instructed to lie quietly and count sheep. It is doubtful that this homespun remedy for sleeplessness would persist over the years if it did not help some people some of the time.
The problem, from a scientific perspective, concerns proper experimental controls. Controls for distraction or for just sitting or lying quietly and undisturbed are seldom found in the many studies that demonstrate positive benefits, such as reduction in respiration and heart rate, and in experiences of stress, such as anxiety or anger (Cheaper and Giber, 1978; Delmonte, 1985). Indeed, when resting-only controls are present, there is virtually no evidence that reductions in somatic arousal (heart rate, respiration rate, skin conductance fluctuations, blood pressure) are any less than those found in experienced meditators who are meditating (Holmes, 1984). There are some reports of benefits in blood pressure reduction for borderline hypertensives (e.g., Benson, 1975; Patel, 1973), but the combined use of other techniques, such as relaxation, in most studies precludes a clear attribution of any positive effects to meditation by itself (Delmonte, 1984, as cited in Brener and Connally, 1986). Patel (1976) for example, says that in addition to meditation, patients must make life-style changes to reduce conflict, a sensible enough conclusion and one that is consistent with the growing recognition that successful interventions must usually be multifaceted (Davison and Neale, 1990).
Overall, our assessment of the scientific research on mediation leads to the conclusion that it seems to be no more effective in lowering metabolism than are established relaxation techniques; it is unwarranted to attribute any special effects to meditation alone. The rest of this section discusses several kinds of studies that underlie our conclusions.
The Pit Burial Studies
The most striking presumed benefits of meditation are found in reports from “pit burial” studies. There is a tradition in India that certain highly regarded yogis can perform superhuman feats. One such feat is to be buried alive for 1 or 2 days. Special importance is attributed to the mystique of the meditation and the yogis' general life-style. In a pit burial, the person lies supine in a board-covered pit underground or in an airtight box above the ground. The longest recorded period survived by a human being was reported by Vakil (1950). After 62 hours, the man emerged stuporous but alive. So startling were these reports that in
1960 the government of India established a committee to study yogic practices as part of an investigation of indigenous medicine. Most controlled research in the West has been conducted in conjunction with this Indian effort.
Mammals, of course, produce carbon dioxide when they exhale, and it is normal for the respiration rate to increase as carbon dioxide concentrations increase. Thus, breathing in an airtight box gradually uses up oxygen at the same time it produces carbon dioxide; the trick is to breathe as slowly as possible, thus using up the least amount of oxygen, but this requires that one suppress the normal mammalian reflex to breathe more rapidly as carbon dioxide increases. In this connection, we note that evidence supports the assertion that meditation reduces metabolic rate, probably through a reduction in respiration rate.
In one study, an experienced yogi instructor had a lighted candle with him in an airtight box. The candle went out after 3 hours, but the yogi remained there for an additional 5 hours. On another occasion he spent 10 hours alone in the box. It was found that his oxygen intake decreased by 40 to 50 percent. At the end of his ordeal, the air he was breathing contained 15.8 percent oxygen and 4.4 percent carbon dioxide; the proportions for air at sea level are 20 percent and less than 2 percent, respectively. Thus, the actual air available for consumption was not very different from regular air. Another study showed that as long as carbon dioxide concentrations did not exceed 7 percent and as long as oxygen concentration was at least 12 percent, a person could remain alive in a box.
In our view the renowned yogic feat is probably due not to special properties of meditation, but rather to confidence in one's ability to slow down one's respiration rate and to the faith that one can survive the ordeal if only one does not panic (and thereby use up more oxygen than normal). For a nonmystical Westerner, it would seem that what is required is knowledge of the scientific facts as summarized above and a confidence in one's skills to lie still and reduce one 's respiration rate. Faith in one's “captor” would also seem important, as would the availability of a “panic button” to gain early release if one felt the need to ask for it. It is well known and reported in the committee's earlier report (Druckman and Swets, 1988) that perceived control and predictability are inherently anxiety-reducing. Religious faith and patriotism may well be powerful forces that enable people to cope under highly stressful circumstances; these possibilities remain to be investigated.
The Generalization Problem
A central problem for any intervention is whether benefits such as reduced anxiety, achieved during a therapeutic or training session, generalize to everyday situations. Consideration of the value of any stress
management method must include the conditions of its application. For example, if a person's task is to lie still in a confined space and “just” control his anxieties so that he does not panic after hours or days, then meditation, relaxation, or prayer can be useful. We have seen from the pit burial studies that enough oxygen is available even in an airtight space for a person to survive for hours—provided the person maintains a low respiration rate—and this goal is achieved more readily if the person does not panic. But if the situation calls for performing a complex sensorimotor task, such as firing a rifle or reading a radar screen, engaging in meditation would seem impossible if not counterproductive, and there are no data suggesting otherwise.
The most supportive data come from relaxation/meditation/biofeedback studies that show lasting reductions in blood pressure following proper training (DiTomasso, 1987). However, the issue here is what accounts for this generalization of effects: Does the person take time out during the day to relax or meditate, or is there some more enduring, systemic reduction in arousal level that does not require conscious attention and practice? Other explanations of lasting reductions would consider changes brought about by the person's lowered reactivity or anger and the positive social-environmental effects that such internal changes might cause. In addition, any consideration of meditation would have to include the religious component, at least insofar as it would seem to provide a strong motivation to practice and apply the techniques.
We conclude that data do not exist to answer the generalization question. The laboratory findings that do exist fail to demonstrate that meditation itself enhances a person's ability to reduce arousal from a stressor (Holmes, 1984). Similar criticisms can be made of the effects of relaxation alone, that is, training and encouraging people to relax their muscles and calm their minds. Although there is overlap with some meditation techniques, relaxation training is readily distinguishable insofar as it does not try to teach a person to gain philosophical-religious insights or to get close to a supreme being. But as with meditation, the interesting and still unanswered question is how generalization is achieved—perhaps a person must be taught to relax differentially in actual stressful situations (see Goldfried and Davison, 1976:98). Or, as with meditation, an answer might be found in the establishment of a more supportive environment and life-style. For example, learning to relax and to enjoy good feelings may prompt a person to make positive changes in his or her work and personal situation, thereby reducing the general stressfulness of the social environment.
Another possibility for most meditation practices relates to the philosophical context. It may be that meditation and relaxation, including
relaxation achieved with certain forms of biofeedback, effect cognitive change. Recent evidence in support of this is available in a report by Davison et al. (in press), who found that intensive relaxation training reduced blood pressure in hypertensives more so than in a group given nonpharmacological medical information and also reduced anger and hostility in subjects' thoughts. Moreover, reductions in hostility and anger were positively correlated with reductions in cardiovascular activity, which is consistent with the hypothesis that cognitive changes brought about, in part, by relaxation training contribute to reductions in hypertension.
Review of the Literature
In 1986 the Army Research Institute commissioned a review of the literature on meditation by Brener and Connally of the University of Hull in England. In this section we summarize the key conclusions reached by the authors, note what research is needed, and discuss possible implications for performance. In the next section we present and comment on a specially commissioned critique of the review.
The Brener-Connally review concentrates primarily on the role of meditation in reducing stress and hypertension. They find that research to date supports claims that meditation produces relaxation or stress reduction. The effects of meditation are unlikely to be due to “ exotic” factors: subjective effects (e.g., relaxed feelings) may be the result of alterations in blood chemistry brought about naturally through normal bodily processes. They find it is difficult to separate the “unique” effects of meditative procedures from more general “atmosphere” effects including the patient's (meditator's) beliefs and the therapist's (instructor's) confidence. Overall, there are few cases in which meditation is shown to be more effective than other treatments for stress and anxiety.
Brener and Connally conclude that reported feats of endurance such as pit burials are likely to be due to the effect of meditation or deep relaxation on metabolism. A lowered metabolism may allow for survival under conditions of restricted oxygen availability. Effects on metabolism can be produced by controlling respiration in the manner practiced by yogis.
Many promoters of meditation are more concerned with demonstrations of the experience than with experimental evaluations of the procedure. Little progress has been made in attempts to understand the underlying mechanisms for observed effects of meditation. Experimental
work to date is characterized by weak designs: a lack of control for subject selection, experimenter biases, expectancies, and atmosphere effects. Work on meditation has led to speculations regarding presumed links between psychological processes (e.g., states of nonanalytical thought) and physiological processes (e.g., neural activity, blood pressure).
Like the research literature on various forms of psychotherapy, the study of meditation would benefit from better experimental designs with proper controls and baselines for judging change. A promising area of investigation is an examination of the pathways through which psychological manifestations of meditation are produced. The better resolutions provided by new brain-scanning technologies may elucidate what happens in the brain during meditation.
Further work is needed on the psychological or institutional context for the practice of meditation. Particular attention should be paid to the Army context in relation to adoption of nontraditional training techniques. More attention should also be paid to the medically-relevant claims for the treatment of anxiety, pain, and disease as well as the medical implications of sustained attention. Finally, linkage between the documented effects of meditation and performance remains an uncharted topic: are there “unique” effects of meditation on performance that differ from those shown to result from other (nonmeditative) procedures that reduce stress?
Implications for Performance
The Brener-Connally review makes clear how little we know about relationships between physiological measures (e.g., electroencephalogram, heart rate) and psychological changes such as attitudes reported for meditation and performance in any situation. Experiments are needed that explore hypothesized relationships between changes in the physiological or psychological variables and changes in the way people perform on well-defined tasks. A start along these lines is the work done by Beatty and his colleagues in the 1970s (e.g., Beatty et al., 1974; Beatty and O'Hanlon, 1979). They focused on vigilance performance as manifested in such tasks as radar monitoring. They did not, however, examine links between meditation effects and motor or cognitive performance.
The review discusses the many complex issues that surround evaluations of meditative practices. It also points to the conclusion that a good deal of research is needed to document the possible links to performance. On the basis of this conclusion, it would seem appropriate to
pursue a program of basic research designed to relate meditative practices to performances on relevant tasks. If the effects of meditation reviewed in the Brener and Connally paper are replicable, there is reason to believe that those effects would intervene between the procedures and observed performances. There may, however, be some gaps in their coverage of meditation as noted in the next section.
CRITIQUE OF THE LITERATURE REVIEW
In an effort to give as much consideration as possible to the military application of meditation, the committee commissioned David Shannahoff-Khalsa, a practitioner of yogic techniques, to write a critique of the Brener and Connally review paper.
The critique by Shannahoff-Khalsa (1990) contains four major points. First, the Brener-Connally paper covers only 300 of 1,200 published studies on meditation and relies on texts written by people who are not “masters.” There is also too much focus in the review on the Buddhist meditation method. Second, Brener and Connally also lack familiarity with certain yogic practices, most especially Kundalini Yoga, as learned by Shannahoff-Khalsa from the Yogi Bhajan. Third, in an extended discussion and description of Kundalini Yoga techniques, Shannahoff-Khalsa notes that they are reported to be very effective for controlling stress, pain, and fatigue; it is claimed these techniques cure various mental disorders and generally enhance human performance through the development of a powerful mind and body. Included is a technique “for developing a penetrating force that cannot be matched by any contemporary techniques available in the military today” (1990:28). Fourth, Shannahoff-Khalsa makes proposals for research along with the caution that knowledge of the techniques not be disseminated widely because of their great power.
Great emphasis is placed by Shannahoff-Khalsa on a book by Murphy and Donovan (1988) that reviews more than 1,200 meditation studies, many more than those covered by Brener and Connally. Furthermore, the authors are self-labelled meditation devotees, while Brener and Connally avowedly are not. He goes on to say that another meditation expert, Deane Shapiro, asserts that the Murphy-Donovan book “gives a fair analysis of this literature.”
Although Shannahoff-Khalsa says that Brener and Connally are fair in their appraisal, he asserts that they have overgeneralized from a limited source base, although he admits that no one can assimilate all the
literature on meditation. One glaring weakness is in their treatment of the yogic perspective. According to Shannahoff-Khalsa, their coverage is adequate for Buddhist-Vipassana, transcendental, and Zen meditation, but not for Kundalini Yoga. Nevertheless, he tends to agree with Brener and Connally's overall judgment that there is no consensus on how to define meditation, how to do it, whether its results are superior to other psychological techniques such as relaxation, and whether the published studies contain too many methodological flaws to permit clear conclusions.
Shannahoff-Khalsa is critical, however, of Brener and Connally's reliance on transcendental meditation and related work by Benson (1975) on “the relaxation response.” Both transcendental meditation and Benson's procedure, he asserts, make a person “overly sensitive” to the extent that they become passive and withdrawn. Yogi Master Bhajan concluded this from transcendental meditation practitioners who came to study with him, and Shannahoff-Khalsa agrees on the basis of his own 2-year experimentation with transcendental meditation, during which time he found himself becoming temperamental and touchy. He concludes that even if performed only 20 minutes a day, as the Maharishi and Benson suggest, such practice harms the person in that it induces a retreat into a silent realm, produces a passive attitude toward the external world, and reduces active coping. In general, he is critical of silent meditation and any form that does not require sitting with an erect spine and that is not more complex and structured than transcendental meditation. The problematic evidentiary bases of these conclusions are clear.
According to Shannahoff-Khalsa, the biggest omission of Brener and Connally has to do with yogic techniques from India and the Chi-gong (life-force) techniques from China. While there is no clear division between meditation and yoga, the former requires less motor activity. He says that the parent of all yogic practices is Kundalini Yoga as taught by Yogi Bhajan. Much of Shannahoff-Khalsa's paper contains excerpts from his other writings that detail Kundalini techniques and physiological rationale and provide recommendations for their use by the military. In his paper on stress technology medicine, he argues that the nasal cycle is a simple parameter for assessing autonomic-central nervous system interrelationships as well as a means of determining left- and right-brain dominance. Stress, he asserts, results from how long and how frequently a swing in homeostatic imbalance is maintained. Moreover, nasal obstruction in the left or right nostril can be related to psychopathology and stress.
On the basis of these neurophysiological speculations, Shannahoff
Khalsa proposes numerous exercises, many of which entail unilateral forced nostril breathing. He cites some of his own studies that purport to show that unilateral forced breathing could stimulate the contralateral hemisphere, producing relatively greater amplitudes in the electroencephalogram. He says that this effect is consistent with relationships of the nasal cycle and cerebral rhythm from yogic medicine. He also says recent data of his group purport to show that such breathing has predictable positive effects on cognitive performance by rectifying imbalance in the autonomic nervous system.
The committee finds these claims unwarranted. Specifically, the idea that too much left-brain activity and right sympathetic dominance may be what we think of as stress cannot be supported by any empirical data. Furthermore, this assertion is not consistent with contemporary scientific theories about the neuroendocrinology of stress (e.g., Weiner et al., 1989). One empirical study has attempted to address the possibility that one hemisphere may participate to a greater extent than the other in triggering the cascade of cognitive, affective, and biochemical events that we call stress. Using salivary cortisol secretion as a biologic marker of stress response, Wittling and Pfluger (1990) found that the right hemisphere (and not the left, as predicted by Shannahoff-Khalsa, 1991) is differentially active in producing the stress response.
Would the techniques recommended by Shannahoff-Khalsa, if indeed they had the proposed effect, influence the perception of stress and its biologic concomitants? There exists in the neuropsychology literature a small and inconclusive group of studies that have examined the relationship between unilateral forced nostril breathing and how it may influence behavior and indices of brain function (e.g., electroencephalogram). These empirical studies (Werntz et al., 1983; Werntz, 1987; Klein et al., 1986; Block et al., 1989) contain some support for the notion that unilateral nostril breathing may have an effect on cognitive performance and electroencephalogram activity. Overall, however, this literature raises many more questions than it answers.1 Moreover, the committee queries whether the effects, if any, have application to complex behavioral tasks that are encountered in the real world.
Shannahoff-Khalsa also describes in some detail a number of yogic exercises taught to him by Yogi Bhajan. Though not yet proven valid by science, these exercises are effective for many purposes, he says, including stress management and control of some psychopathologies such as obsessive-compulsive disorder (one of the most difficult nonpsychotic disorders to treat). He believes that “our future holds the possibility for developing a near stress-resistant and disease-resistant individual” (1990:47) if such techniques are properly taught and faithfully practiced.
In another paper on advanced neuropsychological technology pro-
grams, Shannahoff-Khalsa (1987) asserts that Kundalini Yoga can make soldiers markedly resistant to the highest stress; he strengthens this assertion with references to Tibetan monks carrying out extreme activities, such as being isolated for 3 years. He proposes training programs and research and sees Kundalini Yoga as the best way to prepare military personnel for the extreme mental and physical challenges of modern and future warfare.
Shannahoff-Khalsa concludes by asserting that, of all the forms of meditation, Kundalini Yoga has the most promising implications for the military, that its skilled application can help develop “the soldier-saint” in whom is deeply instilled the desire to excel in the art of warfare. So convinced is he of the power of these techniques that he urges great caution in their dissemination. This caveat assumes that Kundalini Yoga is as powerful as he asserts. The committee does not find evidence to support that conclusion.
A CAUTIONARY NOTE ON EPISTEMOLOGY
It must be noted that it is very difficult for nonmeditation experts and thoroughly Western scientists like the members of the committee to evaluate many of the claims like those of Shannahoff-Khalsa. He is deeply immersed in Kundalini Yoga and conducts both his personal and professional life in keeping with the philosophical and procedural requirements of that practice. He asserts, as do some psychoanalysts, that one cannot know a complex and powerful system unless one experiences it in a deep and thoroughgoing way. No one on our committee has done this with Kundalini Yoga or, for that matter, with the other meditation practices we have reviewed. This epistemological issue has important policy implications. Contemporary science is but one way of knowing. It is, however, the way of knowing that characterizes the work of this committee. At the same time, it seems appropriate to be mindful of the constraints that science, as well as culture, background, and personal life experience, places on how the committee views the field of meditation.
The scientific literature on meditation indicates that controls for distraction or for just sitting or lying quietly and undisturbed are seldom to be found in the many studies that demonstrate positive benefits from meditation. When appropriate controls are present, no evidence supports the notion either that meditation reduces arousal any more than does simply resting quietly or that meditation permits a person to better cope with a stressor. When meditation has been found to be effective for such
things as reducing hypertension, the combined use of other techniques, such as relaxation training, precludes a clear attribution of any positive effects to meditation itself. Life-style changes to reduce conflict are also apparently instrumental, a sensible enough conclusion and one that is consistent with the growing recognition that successful interventions must usually be multifaceted.
The highly publicized feats of some yogis who can remain buried for many hours without suffocating are probably due not to any special properties of meditation, but rather to confidence in their ability to slow down their respiration rate as well as faith that they can survive the ordeal if only they do not panic and use up more oxygen than normal. Consistent with findings from the committee's earlier report, perceived control and predictability are inherently anxiety-reducing. A related possibility concerns the philosophical context for most meditation practices. It may be that meditation and relaxation (and perhaps also relaxation achieved with certain forms of biofeedback) effect cognitive change, not the least of which may be an enhanced sense of self-efficacy, a belief that one can control one's stress reactions to some extent.
A particular challenge to those who advocate meditation is whether in-session benefits generalize to everyday situations or to conditions of special challenge. Does a person take time out during the day to meditate, or is there some more enduring, systemic reduction in arousal level which does not require conscious attention to practice? Perhaps interpersonal, social context changes are brought about by the person's lowered reactivity to challenge, and these positive social-environmental shifts present the individual with a less stressful environment. We do not believe that data exist to answer this question.
There is no scientific evidence to support the assertion that the proper application of Kundalini Yoga can help develop “the soldier-saint ” in whom is instilled the superhuman desire and ability to excel in the art of warfare.
1. Block et al. (1989) found that unilateral forced nostril breathing influences spatial and verbal performance, but with opposite results for males and females. Werntz and his colleagues (Werntz et al., 1983; Werntz, 1987) employed the unusual assumption that greater integrated electroencephalogram amplitude over a particular hemisphere indicates that it is dominant at the time. (The traditional interpretation is that fast, low voltage activity reflects decreased cortical activation.) Furthermore, in the Werntz et al. study, there were five subjects, only one of which showed shifts in EEG symmetry. Klein et al. (1986) found that free breathing subjects showed a small correlation between nostril dominance and cognitive performance and that unilateral nostril breathing does not influence cognitive performance. Based on this evidence it would seem premature to suggest that this approach be used for stress reduction.
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