Self-report questionnaires that claim to measure mindfulness as a personality trait face serious, possibly intractable problems. These include a lack of external benchmarks to verify what the scales actually measure, poor content validity, and evidence that people's self-ratings do not match their actual behavior. Different mindfulness scales fail to agree with each other, and responses are biased by a person's experience with meditation. The scales may distort and trivialize the original Buddhist concept of mindful awareness, harming both research and the development of mindfulness-based interventions. A deeper understanding of mindfulness, grounded in direct, long-term meditative practice and Buddhist phenomenology, is needed before psychologists attempt to quantify it.
A randomized trial with 130 participants tested whether the Five Facet Mindfulness Questionnaire (FFMQ) validly measures dispositional mindfulness. The study included three groups: mindfulness-based stress reduction (MBSR), an active control condition (Health Enhancement Program, HEP) that did not teach mindfulness meditation, and a waitlist control. At baseline, FFMQ facets correlated with measures of psychological symptoms and well-being, providing partial evidence for convergent validity. FFMQ scores increased for MBSR relative to the waitlist, but they also increased for HEP relative to the waitlist, and MBSR and HEP did not differ from each other. The FFMQ thus failed to show discriminant validity, raising questions about its ability to specifically measure mindfulness.