Psychological Effects of Meditation for Healthy Practitioners: an Update

In recent years, interest in the effects of meditation has increased considerably, which might have had an impact on the outcomes as well as on the methods used. The present meta-analysis summarizes the effects of meditation for healthy practitioners for the years 2011 to 2015, thereby complementing a previous summary that covered the four decades before. We found a global effect size for studies with conventional controls (r) over bar = .27 (n = 54), comparable to the earlier analysis, as well as a smaller but apparently stable effect (r) over bar = .17 when meditation groups were compared to active controls (n = 16 studies). As in the previous summary, results were strongest for relationship issues and relatively strong for measures of intelligence and the self-concept, but effects were markedly smaller for negative emotions and anxiety. Also, in contrast to the previous analysis, meditation experience and length of meditation training correlated positively with the strength of meditation effects. Unfortunately, most studies still appear to have been conducted without sufficient theoretical background, and dependent measures seem largely to have been chosen ad hoc. We emphasize that meditation research will only make real progress if more effort is spent on developing precise theories and measurement devices.