Limited Validity of Breath-Counting as a Measure of Mindfulness in Ruminative Adolescents.

Objective measurement of mindfulness could help us understand the mechanisms of meditation interventions and how individuals vary in their disposition to be mindful. One proposed measure is the breath-counting task (BCT), which measures how accurately one can count cycles of their breath. Breath counting, which involves sustained attention, meta-awareness, and an internal locus of attention, has been shown in adults to be related to measures of mindfulness even when controlling for established attentional measures. In this study, we test the psychometrics of the BCT in a convenience sample of 78 adolescents with elevated rumination. In preregistered analyses, we related breath-counting measures, including novel objective respiration measures, to a suite of self-report measures as well as the sustained attention to response task (SART). While breath-counting performance showed fair split-half reliability and similar distributions to studies in adults, it did not show the expected positive associations with self-reported mindfulness measures (neither trait nor EMA). Surprisingly, breath-counting accuracy showed negative correlations with a subscale measuring observing of emotions and body sensations, negative correlations with nonreactivity, and performance decrements were larger for individuals scoring more highly on mindfulness in general. The SART showed a small negative correlation with breath-counting resets (an index of mind-wandering). Finally, breath-counting performance was not related to other theoretically relevant clinical, personality, and executive functioning criteria. Our results suggest that, at least in ruminative adolescents, breath-counting may measure a very narrow, contextual form of sustained attention, may not capture other qualities of mindfulness, and may lack predictive validity.