Michelle Craske & colleagues from the Anxiety Disorders Research Center of UCLA have, for many years, been publishing careful, challenging research on underlying mechanisms & on ways of boosting the effectiveness of exposure therapies for different forms of anxiety.  Craske's list of publications & research presentations runs to 31 pages and begins with a study on musical performance anxiety published in 1984.  As the presentation titles on her list show, for some years the majority of her many lectures at prestigious conferences all over the world have revolved around the theme of how to take evolving scientific findings about fear learning and use them to optimize exposure treatments for anxiety disorders.  Her recent paper "Maximizing exposure therapy: An inhibitory learning approach" is something of a tour de force in this area.  Its abstract reads "Exposure therapy is an effective approach for treating anxiety disorders, although a substantial number of individuals fail to benefit or experience a return of fear after treatment.  Research suggests that anxious individuals show deficits in the mechanisms believed to underlie exposure therapy, such as inhibitory learning. Targeting these processes may help improve the efficacy of exposure-based procedures.  Although evidence supports an inhibitory learning model of extinction, there has been little discussion of how to implement this model in clinical practice.  The primary aim of this paper is to provide examples to clinicians for how to apply this model to optimize exposure therapy with anxious clients, in ways that distinguish it from a ‘fear habituation’ approach and ‘belief disconfirmation’ approach within standard cognitive-behavior therapy.  Exposure optimization strategies include 1) expectancy violation, 2) deepened extinction, 3) occasional reinforced extinction, 4) removal of safety signals, 5) variability, 6) retrieval cues, 7) multiple contexts, and 8) affect labeling.  Case studies illustrate methods of applying these techniques with a variety of anxiety disorders, including obsessive-compulsive disorder, posttraumatic stress disorder, social phobia, specific phobia, and panic disorder."

If you don't have a subscription to the journal of Behavior Research and Therapy, it will cost you $19.95 to get access to the full text of "Maximizing exposure therapy".  My usual work-arounds are to visit the university department website to check if they have a list of downloadable PDF's or to write appreciatively to the corresponding author asking if they will email a full copy of the article.  You can get much of the same information freely through Research Gate with the full text of their 2012 publication "Role of inhibition in exposure therapy" (although this paper doesn't provide the helpful illustrative case examples found in the 2014 article).  The abstract of this latter paper reads "While many researchers have largely focused on principles of systematic desensitization and habituation in explaining fear extinction, these processes have mixed evidence at best.  In particular, these models do not account for spontaneous recovery or reinstatement of fear, nor do they explain the context dependency of extinction or rapid reacquisition.  This may in part account for the significant number of patients who fail to respond to our available treatments which rely on these principles in designing exposure sessions.  However, recent research is converging to suggest that an inhibitory model of fear reduction, in which the original feared association (CS-US) remains but is inhibited by a newly formed association (CS-noUS) representing safety, holds promise in explaining the long-term attenuation of fear and anxiety.  This paper reviews research in a number of areas, including neuroimaging, psychophysiology, and psychopharmacology that all provide support for the inhibition model of anxiety.  Limitations to this body of research are discussed, along with recommendations for future research and suggestions for improving exposure therapy for fear and anxiety disorders.  Clinical implications discussed in this paper include incorporating random and variable practice in exposure sessions, multiple contexts, and pharmacological aides, among others."

Exposure-based methods for treating anxiety disorders are so central to the "bread-and-butter" skills of CBT therapists, it seems very important that we take on board any useful developments in this area.  In their 2014 paper, Craske & colleagues come up with a series of eight "strategies for enhancing inhibitory learning".  In a helpful table, they list each strategy with a brief description and a memory-jogging "catch-phrase" they have found useful in expressing the strategy's rationale to clients.  The eight strategies are: 

1.)  Expectancy violation.  Design exposures to violate specific expectations.  Test it Out.

2.)  Deepened extinction.  Present two cues during the same exposure after conducting initial extinction with at least one of them.  Combine It.

3.)  Reinforced extinction.  Occasionally present the US during exposures.  Face Your Fear.

4.)  Variability.  Vary stimuli and contexts.  Vary It Up.

5.)  Remove safety behaviors.  Decrease the use of safety signals and behaviors.  Throw It Out.

6.)  Attentional focus.  Maintain attention on the target CS during exposure.  Stay With It.

7.)  Affect labeling.  Encourage the clients to describe their emotional experience during exposure.  Talk It Out.

8.)  Mental reinstatement/retrieval cues.  Use a cue present during extinction or imaginally reinstate previous successful exposures.  Bring It Back.

In the summary to their paper Craske & colleagues conclude: "The translation from extinction learning to exposure therapy for fear and anxiety disorders involves directly targeting the initial acquisition, consolidation, and later retrieval of new learning.  While the focus of the exposure may differ depending on the psychological condition being treated, in each case exposure therapy will generally contain the following elements.  First is the specific goal of the exposure therapy: together, the therapist and client decide on the specific goal of the practice in terms of duration or behavioral goals in specific and measurable terms.  Second is the anticipated negative outcome: the therapist elicits from the client the particular feared outcome of engaging in the task.  Exposures are then designed in such a way and proceed until a given anticipation or expectation is violated.  Third is recognition and consolidation of the non-occurrence of the anticipated event: following completion of an exposure practice, therapists aid clients in discussing the non-occurrence of the feared event.  This reflects consolidating the new learning regarding the non-contingent relationship between the conditional stimulus and the unconditional stimulus.  In addition, exposure includes “inhibitory learning enhancement and inhibitory regulation enhancement strategies”, including deepened extinction (or exposure to multiple feared cues), occasionally reinforced extinction (or occasional exposure to aversive outcomes), weaning from safety signals, stimulus and response variability, retrieval cues, multiple contexts, and affect labeling ... Framing exposure within a modern learning theory perspective holds numerous advantages including providing a parsimonious explanation for shared elements of traditional exposure (or, behavioral experiments), while simultaneously explaining their shortcomings.  In addition, it ties clinical research to the wealth of research on learning theory in animal and human populations.  Third, it holds promise for improving the efficacy of exposure- based procedures through selective targeting of associative learning mechanisms.  Associative learning theories provide a parsimonious explanatory model from which to situate exposure processes.  However, additional translational research is needed to further elucidate the optimal conditions necessary for enhancing inhibitory regulation and the precise methods for implementing these strategies in routine clinical care."