A systematic review and meta-analysis of the evidence for unaware fear conditioning

•The available evidence for contingency unaware fear conditioning was assessed.•39 of the 41 included studies suffered from one or more methodological problems.•No evidence was found for moderators of contingency unaware fear conditioning.•P-curve analysis and funnel plot asymmetry indicated substantial publication bias.•We conclude that there is no evidence for contingency unaware fear conditioning. Whether fear conditioning can take place without contingency awareness is a topic of continuing debate and conflicting findings have been reported in the literature. This systematic review provides a critical assessment of the available evidence. Specifically, a search was conducted to identify articles reporting fear conditioning studies in which the contingency between conditioned stimuli (CS) and the unconditioned stimulus (US) was masked, and in which CS-US contingency awareness was assessed. A systematic assessment of the methodological quality of the included studies (k = 41) indicated that most studies suffered from methodological limitations (i.e., poor masking procedures, poor awareness measures, researcher degrees of freedom, and trial-order effects), and that higher quality predicted lower odds of studies concluding in favor of contingency unaware fear conditioning. Furthermore, meta-analytic moderation analyses indicated no evidence for a specific set of conditions under which contingency unaware fear conditioning can be observed. Finally, funnel plot asymmetry and p-curve analysis indicated evidence for publication bias. We conclude that there is no convincing evidence for contingency unaware fear conditioning.