Meditation is a family of mental training practices that familiarize practitioners with specific mental processes. In age-matched participants, using functional MRI, activation in brain regions involved in sustained attention showed an inverted u-shaped curve: expert meditators with an average of 19,000 hours of practice had more activation than novices, but experts with an average of 44,000 hours had less activation. In response to distracter sounds, experts versus novices had less brain activation in regions related to discursive thoughts and emotions and more activation in regions related to response inhibition and attention. Correlation with hours of practice suggests possible plasticity in these mechanisms.
A behavioral measure of mindfulness, breath counting, was validated across four studies involving over 400 participants. Breath counting was reliable, correlated with self-reported mindfulness, distinguished long-term meditators from age-matched controls, and was distinct from measures of sustained attention and working memory. Greater skill in breath counting was associated with more meta-awareness, less mind wandering, better mood, and greater non-attachment. A randomized online training study found that four weeks of breath counting training improved mindfulness and decreased mind wandering compared to working memory training and no training controls. These findings support breath counting as a behavioral measure of mindfulness.