"All we have to fear is fear itself": Paradigms for reducing fear by preventing awareness of it.

Research on unconscious fear responses has recently been translated into experimental paradigms for reducing fear that bypass conscious awareness of the phobic stimulus and thus do not induce distress. These paradigms stand in contrast to exposure therapies for anxiety disorders, which require direct confrontation of feared situations and thus are distressing. We systematically review these unconscious exposure paradigms. A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-based search yielded 39 controlled experiments based on 10 paradigms that tested whether exposure without awareness can reduce fear-related responses. In randomized controlled trials of phobic participants, unconscious exposure interventions: (a) reduced behavioral avoidance (weighted mean d = 0.77, N = 469) and self-reported fear (d = 0.78, N = 329) during in vivo exposure to feared situations; (b) reduced neurobiological indicators of fear and enhanced such indicators of fear regulation (d = 0.81, N = 205); (c) had significantly stronger effects on reducing symptomatic behaviors and enhancing neurobiological indicators of fear regulation than did conscious exposure (d = 0.78, N = 342); and (d) produced these effects without inducing subjective fear. In fear-conditioned participants, unconscious exposureinduced extinction learning (d = 0.80, N = 420), even during sleep, and yielded somewhat stronger extinction learning than conscious exposure did (d = 0.44, N = 438). We organize these findings within a neuroscientific framework and evaluate alternative mechanisms for unconscious exposure. The use of incommensurate outcome measures across exposure paradigms and nonreporting of relevant statistics limited meta-analyses. Despite steps taken to address publication bias, 25.6% of included studies came from a single laboratory. We propose potential clinical applications of these findings. Future research should clarify underlying mechanisms, use common outcome measures, and explore effects on other anxiety disorders. (PsycInfo Database Record (c) 2024 APA, all rights reserved).