Psychophysiological investigations on transcendental meditation.

Two experiments were conducted to evaluate the psychophysiological changes reported to occur during the practice of transcendental meditation. In Experiment I, 47 volunteers solicited from the community were randomly assigned to transcendental meditation (TM), Benson's relaxation response (BRR), or no treatment (NT) instruction. Respiration rate, heart rate, electromyogram, electroencephalogram, and skin conductance level were recorded during the practice of each technique, approximately 1 week after terminating instruction. The results indicate that while BRR, TM, and NT exhibited different physiological patterns, none of the techniques showed a clear superiority in reducing tonic physiological arousal. In Experiment II, 30 volunteers with previous experience were assigned to one of the three groups based on their meditating experience (range 16-96 months). The same physiological signals as in Experiment I were also recorded in this experiment during TM practice. The results suggest that individuals with 1.5 years of meditation experience exhibited physiological arousal levels similar to those seen in persons with over 5 years' experience.