Abstract
In 2017, Lindsay and Creswell proposed the Monitor and Acceptance Theory (MAT) of mindfulness, which proposed a unified and testable framework for interpreting and predicting different mindfulness effects on attention, affective reactivity, emotion regulation, and health-related variables. MAT identifies two basic mindfulness skills: attention monitoring and acceptance. The theory is articulated in two main tenets, affirming that attention monitoring increases present-moment awareness and emotional reactivity (Tenet #1) while acceptance regulates the affective experience (Tenet #2). Therefore, MAT proposes that monitoring per se could also have a negative psychological outcome, while it should lead to positive outcomes when combined with acceptance. Even though MAT is founded on a reasonable basis and is apparently supported by the existing literature, we identify four main issues in the literature cited in support of MAT. In particular, the main issues regard the way in which MAT skills were defined and measured (Issue #1), the inconsistent effect of monitoring alone on emotional reactivity (Issue #2), the inconsistent moderation effect of acceptance on monitoring in determining (positive) health-related outcomes (Issue #3), and the current absence of substantial testing on MAT Tenet 2, considering the effect of acceptance alone on mindfulness interventions (Issue #4). In this manuscript, we review the main contributions to each of these points and show a number of results that do not support MAT or contrast its tenets. In particular, we focus on the recent intervention studies aiming at dismantling the effect of mindfulness on mental health. After a close analysis, we concluded that they failed in testing the MAT tenets and thus provide only insubstantial or incomplete evidence in favor of or against MAT. While we support the aim of MAT theory and its tentative systematization of the vast literature on mindfulness, we would like to highlight its weak or controversial points so to further promote its development and testing with more compelling methods.