For decades many people have claimed meditation can change how we behave towards others and make us more compassionate.
But now new research has suggested meditation's role in making individuals better people is limited.
The study by scientists at Coventry University in the UK, Massey University in New Zealand, and Radboud University in the Netherlands, reviewed more than 20 studies that investigated the effect of various types of meditation, such as mindfulness and loving-kindness, on pro-social feelings and behaviours.
Initial analysis indicated that meditation did have an overall positive impact.
The researchers said meditation made people feel moderately more compassionate or empathic, compared to if they had done no other new emotionally-engaging activity.
However further analysis revealed that it played no significant role in reducing aggression or prejudice or improving how socially-connected someone was.
The most unexpected result of this study, though, was that the more positive results found for compassion had important methodological flaws -- compassion levels in some studies only increased if the meditation teacher was also an author of the published report.
Overall, these results suggest that the moderate improvements reported by psychologists in previous studies may be the result of methodological weaknesses and biases, said the researchers.
Their research - published today in Scientific Reports - only included randomised controlled studies, where meditators were compared to other individuals that did not meditate.
All these studies used secular meditation techniques derived from Buddhism, such as mindfulness and loving-kindness meditation, but not other related activities, like yoga or Tai-Chi.
Dr Miguel Farias, from Coventry University's Centre for Advances in Behavioural Science, said:
"The popularisation of meditation techniques, like mindfulness, despite being taught without religious beliefs, still seem to offer the hope of a better self and a better world to many. We wanted to investigate how powerful these techniques were in affecting one's feelings and behaviours towards others.
"Despite the high hopes of practitioners and past studies, our research found that methodological shortcomings greatly influenced the results we found. Most of the initial positive results disappeared when the meditation groups were compared to other groups that engaged in tasks unrelated to meditation. We also found that the beneficial effect of meditation on compassion disappeared if the meditation teacher was an author in the studies. This reveals that the researchers might have unintentionally biased their results.
"None of this, of course, invalidates Buddhism or other religions' claims about the moral value and eventually life changing potential of its beliefs and practices. But our research findings are a far cry from many popular claims made by meditators and some psychologists.
"To understand the true impact of meditation on people's feelings and behaviour further we first need to address the methodological weaknesses we uncovered -- starting with the high expectations researchers might have about the power of meditation."