Experiential avoidance as an early mechanism of an online mindfulness-based intervention for emotional distress: evidence from a behavioral paradigm in a randomized controlled trial

Given the substantial burden of global emotional distress and the proven efficacy of mindfulness-based interventions (MBIs), identifying early mechanisms of MBIs is critical for optimizing treatment adherence and outcomes. This study employed behavioral measures to investigate experiential avoidance as an early mechanism in an online MBI. Eighty-one participants experiencing high emotional distress were recruited. First, the image rating task was conducted at baseline to examine its convergent validity to assess participants’ experiential avoidance. Convergent validity was examined using established self-report measures of experiential avoidance (e.g., AAQ-II and BEAQ). Then, participants were randomly assigned to an 8-week online Mindfulness Intervention for Emotional Distress (MIED) group ( N = 41) or a waitlist control group ( N = 40). Experiential avoidance (both self-reported and behaviorally measured), general emotional distress, anxiety and depression were measured at baseline and week 3 of the 8-week intervention. Results indicated an avoidance-related response pattern, where participants responded faster to negative versus neutral images ( p < .001), and the difference in reaction times between negative and neutral images was significantly correlated with the scores of self-reported experiential avoidance (ps < 0.01). Compared to the waitlist control group, the participants in the MIED group showed significant reductions in general emotional distress, anxiety, depression, and both self-reported and behavioral measures of experiential avoidance at Week 3 ( p s < 0.01). Mediation analyses revealed that reductions in behavioral measures of experiential avoidance partially mediated the effects of the MIED on the reductions in emotional distress and anxiety but not depression at Week 3. The present study provides preliminary evidence for the convergent validity of the image rating task for assessing experiential avoidance. Furthermore, it provides preliminary behavioral evidence supporting a mediational account of experiential avoidance in the early stages of MBIs. These findings suggest that experiential avoidance is a promising early intervention target in MBIs. This study was prospectively registered at ClinicalTrials.gov (NCT05891015). The study was submitted to the registry on May 26, 2023, and first published on June 5, 2023.