Defusion techniques on self-referential thought in laboratory-based experimental research: A meta-analysis of believability and discomfort outcomes

Background Negative self-referential thoughts often acquire aversive and rigid functions through relational framing, contributing to psychological inflexibility. Cognitive defusion techniques aim to alter these verbally derived functions by reducing the extent to which thoughts govern behavior or evoke distress. Despite their centrality in ACT, no meta-analysis has focused specifically on defusion procedures applied to self-referential stimuli or on functionally distinct outcomes such as believability and discomfort. Methods Experimental studies conducted with adult non-clinical samples employing an isolated defusion technique and assessing believability and/or discomfort pre–post intervention were eligible for inclusion. Searches were conducted in PubMed and EBSCOhost through October 30, 2025. Risk of bias was evaluated using the RoB 2 tool. Random-effects models were applied, and subgroup analyses examined differences across defusion procedures. Results Twelve studies (22 samples; n = 659) met inclusion criteria. Defusion produced large reductions in believability (Hedges’ g = 1.04, SE = 0.12) and discomfort (g = 1.12, SE = 0.17). Word repetition yielded larger effects on believability (g = 1.29) than other techniques (g = 0.59), with a similar pattern for discomfort (1.38 vs. 0.76). Discussion Defusion reliably alters both discriminative (believability) and eliciting (discomfort) stimulus functions of self-referential thoughts. Differences across techniques suggest that distinct defusion procedures engage different behavioral processes, highlighting the relevance of analyzing defusion as a procedure, a process, and an outcome within a process-based CBS framework.