سه آزمایش تصادفی بر روی اثرات طولی روش متعالی مدیتیشن بر روی شناخت

Three studies on 362 high school students at three different schools in Taiwan tested the hypothesis that regular practice of the Transcendental Meditation (TM) technique for 15–20 min twice a day for 6 to 12 months would improve cognitive ability. The same seven variables were used in all studies: Test for Creative Thinking-Drawing Production (TCT-DP); Constructive Thinking Inventory (CTI); Group Embedded Figures Test (GEFT); State and Trait Anxiety (STAI); Inspection Time (IT); and Culture Fair Intelligence Test (CFIT). Univariate testing showed that TM practice produced significant effects on all variables compared to no-treatment controls (Ps ranged from .035 to <.0001). Napping for equivalent periods of time as TM practice had no effect. Contemplation meditation improved inspection time and embedded figures, but not the other variables. The TM technique was superior to contemplation meditation on five variables. The effect sizes for TM practice were in the order of the variables listed above.

The hypothesis for the present research was that regular experience of the wakeful hypometabolic state produced by the Transcendental Meditation program develops general cognitive ability Alexander et al., 1990, Dillbeck & Alexander, 1989, Orme-Johnson et al., 1997 and So, 1995. This state is called “wakeful hypometabolic” or “restful alertness” because it is a combination of markedly decreased metabolism, heart rate, respiration rate, etc., as in sleep, together with mental alertness, as indicated by increased EEG alpha power and coherence Dillbeck & Orme-Johnson, 1987, Jevning et al., 1992, Orme-Johnson, 1973, Travis & Wallace, 1999, Wallace, 1970 and Wallace, 1986. A number of physiological changes during the TM technique predict cognitive improvement, such as increased blood flow to the brain Jevning et al., 1996 and Jevning et al., 1978 and increased EEG coherence in parameters that are correlated with cognitive improvement Dillbeck & Araas-Vesely, 1986, Dillbeck & Bronson, 1981, Levine, 1976, Nidich et al., 1983 and Orme-Johnson & Haynes, 1981. Studies of the effects of the TM program on event-related potentials show shorter latency, higher amplitude, and broader cortical representation of sensory and cognitive evoked responses, all predictive of improved cognitive performance Banquet & LeSevre, 1980, Cranson et al., 1990, Goddard, 1989, Kobal et al., 1975, Lyubimov, 1994 and Wandhofer et al., 1976. TM practice has been shown to increase the neuropeptide vasopressin (O'Halloran et al., 1985) and to improve memory Dillbeck, 1982 and Pagano & Frumkin, 1977, which could be expected, since there is evidence that increased vasopressin enhances memory (Van Londen et al., 1998). TM practice also reduces the major stress hormone cortisol, both during meditation (Jevning, Wilson, & Davidson, 1978) and longitudinally outside of meditation MacLean et al., 1997, Walton & Levitsky, 1994 and Walton et al., 1995. The relevance of this to cognition is that studies have shown that increasing cortisol levels impair memory (Lupien & McEwen, 1997), and that prolonged cortisol elevation may induce hippocampal atrophy with associated deficits in hippocampal-dependent memory tasks (Lupien et al., 1998).