The psychological effects of meditation: A meta-analysis.

A meta-analysis of 163 studies on meditation in nonclinical adults found medium average effects (r = .28) on psychological variables, not explainable by relaxation or cognitive restructuring alone. Effects were strongest for emotionality and relationships (medium to large), medium for attention, and small to medium for cognitive measures. Results varied by meditation type (transcendental, mindfulness, other). Meditation experience only partially predicted long-term impact. Most of 595 initial studies were excluded due to methodological problems, and many lacked theoretical grounding. The authors call for more precise theories and measurement tools to understand how meditation works.

Study at a glance

Abstract

In this meta-analysis, we give a comprehensive overview of the effects of meditation on psychological variables that can be extracted from empirical studies, concentrating on the effects of meditation on nonclinical groups of adult meditators. Mostly because of methodological problems, almost ¾ of an initially identified 595 studies had to be excluded. Most studies appear to have been conducted without sufficient theoretical background. To put the results into perspective, we briefly summarize the major theoretical approaches from both East and West. The 163 studies that allowed the calculation of effect sizes exhibited medium average effects (r = .28 for all studies and r = .27 for the n = 125 studies from reviewed journals), which cannot be explained by mere relaxation or cognitive restructuring effects. In general, results were strongest (medium to large) for changes in emotionality and relationship issues, less strong (about medium) for measures of attention, and weakest (small to medium) for more cognitive measures. However, specific findings varied across different approaches to meditation (transcendental meditation, mindfulness meditation, and other meditation techniques). Surprisingly, meditation experience only partially covaried with long-term impact on the variables examined. In general, the dependent variables used cover only some of the content areas about which predictions can be made from already existing theories about meditation; still, such predictions lack precision at present. We conclude that to arrive at a comprehensive understanding of why and how meditation works, emphasis should be placed on the development of more precise theories and measurement devices.