Enhancing Inhibitory Learning: The Utility of Variability in Exposure

Abstract

Exposure therapy has strong empirical support as a treatment for anxiety and related disorders, yet not all participants see clinically meaningful reduction in symptoms, and some experience return of fear. In this review, we examine the theoretical models of exposure therapy, from early precursors to the contemporary inhibitory learning model. The inhibitory learning model is applied to examine one potential method of improving outcomes in exposure therapy: increasing variability in the progression of the exposure hierarchy. We explore mechanisms that support the use of variability in exposure, including the violation of expectancies to enhance learning. In addition, the role of intolerance of uncertainty in anxiety is examined; variable exposure therapy could target this transdiagnostic mechanism in anxiety and related disorders. Suggestions for future research are then offered.

Keywords: Exposure therapy; Inhibitory learning; Intolerance of uncertainty.

Figure 1.

The inhibitory learning model. The weight of the bar pairing the conditioned stimulus (CS) and unconditioned stimulus (US) depicts the strength of the association. A client with a spider phobia may initially associate spiders with receiving a painful bite, based on either past experience or imagined consequences. After fear learning, the spider alone will evoke fear, even without negative consequences. During repeated exposure, the client learns that seeing a spider is unlikely to result in a spider bite – most spiders are harmless and spend their time in webs, not attacking people. This is the CS-no US association. The original CS-US pairing is still intact, because the client knows that some spiders might bite, and there is a remote possibility she could come in contact with one. However, this association has been weakened, because the client has interacted with spiders in a variety of contexts and knows that the chances of a negative outcome are slim and not as severe as she imagined.

Figure 2.

Kate’s exposure hierarchy, variable exposure, and SUDS.

Figure 3.

Laura’s exposure hierarchy, variable exposure, and SUDS.

Figure 4.

Matthew’s exposure hierarchy, variable exposure, and SUDS.