Assessing mindfulness: Experimental support for the discriminant validity of breath counting as a measure of mindfulness but not self-report questionnaires.

The current study sought to examine the discriminant validity of 3 commonly used measures of mindfulness. The discriminative ability of the Mindful Attention Awareness Scale (MAAS), the Five Factor Mindfulness Questionnaire (FFMQ), and a breath counting task (BCT) was assessed in a randomized control trial involving an 8-week mindfulness training (MT) condition (n = 53) and an active control computerized attention training (CT) program (n = 33). No evidence to support the discriminant validity of MAAS or FFMQ scores was found, as these self-report measures responded to both the MT and CT conditions. Breath counting scores however demonstrated unique responsiveness to the MT program, suggesting this behavioral task may be useful in measuring changes in mindfulness as it closely resembles core cognitive processes trained during this practice. Implications of these findings for the construct validity of both self-report and behavioral measures of mindfulness are discussed, along with the suitability of current mindfulness-based interventions in studies aiming to assess mindfulness outcomes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).