Treatment response rates for cognitive behavioral therapy (CBT) across anxiety disorders average approximately 50% post-treatment (Loerinc et al, 2015), evidencing significant 'return of fear', the re-emergence of a partially or fully extinguished fear (Rachman, 1989). Thus, recent research has amplified efforts toward improving treatment methodology in an attempt to optimize clinical outcomes. Many efforts have targeted exposure therapy, an evidence-based behavioral technique during which a patient is strategically and repeatedly exposed to his or her feared stimulus in an effort to generate new non-fear associations with that stimulus. One such effort involves mental rehearsal, where information is reinstated using either a cue from extinction training or imaginal recounting of previous successful exposures (Craske et al, 2014). Prior research has assessed the effects of mental rehearsal via reinstatement of the extinction context (i.e., treatment context) or of cues/items from the treatment context that may indicate safety (e.g., Mystkowski et al, 2006; Culver, Stoyanova, & Craske, 2011). However, this research has produced inconsistent results and contains an inherent limitation, as retrieval cues may become a safety signal and inhibit new learning (Dibbets, Havermans, & Arntz, 2008).

In an effort to address these limitations, the current study recruits spider-fearful participants for a treatment trial consisting of exposures in conjunction with either a mental rehearsal intervention, or a control rehearsal intervention. The overarching goal of this project is to evaluate the extent to which a between-session, technology-guided mental rehearsal intervention may optimize exposure therapy outcomes. We also seek to evaluate potential mechanisms of mental rehearsal.

Participants complete three laboratory visits, including two sessions of exposures with live spiders. Participants are randomized to either a mental rehearsal or control rehearsal condition to measure potential mechanisms and moderators of mental rehearsal. Laboratory-based assessments include measures of subjective, behavioral, and psychophysiological responses to spiders.

Return of fear is the re-emergence of a partially or fully extinguished fear (Rachman, 1989). Due to relatively low treatment response rates for CBT at post-treatment (Loerinc et al, 2015), this study seeks to assess the efficacy of mental rehearsal (MR) in a different, less context-dependent manner than prior efforts (e.g., Mystkowski et al, 2006; Culver, Stoyanova, & Craske, 2011). Participants in the MR condition rehearse the new learning contingency, that is, that their feared outcome did not occur when they approached a live spider. Violation of expectancies engenders new, secondary learning that competes with the older fear memory (Craske et al, 2008; Bjork, 2003). As secondary, non-fear learning is repeatedly retrieved, the original fear memory is gradually suppressed, rendering it less recallable in the future (Bjork, 2011). Thus, repeatedly retrieving non-fear learning acquired from exposures is purported to strengthen the non-fear memory and reduce symptoms of arachnophobia. MR is conducted between sessions in an effort to reduce short-term return of fear by enhancing consolidation of non-fear learning via rehearsal efforts in multiple environments/contexts.

The overall aim of the current study is to evaluate a method for enhancing the effectiveness of exposure therapy, and more specifically, to test the extent to which a novel between-session mental rehearsal intervention may optimize treatment outcomes in individuals with excessive fear of spiders. An important secondary aim is to better understand cognitive and affective mechanisms underlying benefits of mental rehearsal.

The experiment consists of three sessions, spanning 8-10 days. Session 1 begins with a pre-treatment assessment consisting of self-report questionnaires and a behavioral approach test (BAT) with a live spider. During the BAT, confidence and distress ratings are obtained and psychophysiological responses (i.e., SCR) are recorded. Participants then complete a series of exposures with a live spider. At Session 2 (two to three days later), participants return to complete a second series of exposures with a live spider. At Session 3 (five to seven days later), participants complete a post-treatment assessment with self-report questionnaires and BAT, again with concurrent confidence and distress ratings and psychophysiological recordings.

Between sessions, participants are randomized to mentally rehearse information from exposures (i.e., MR) or from an unrelated recent academic experience (i.e., Control). MR exercises guide participants in retrieving and consolidating learning from exposures, emphasizing the inhibitory relationship between the conditioned stimulus (CS) and the unconditioned stimulus (US) (i.e., that approaching the spider did not result in their anticipated/feared outcome).

Measures span self-report, behavioral, and psychophysiological data. Fear of spiders is assessed with self-reported symptoms and measures taken during pre- and post-treatment BATs. During each BAT, skin conductance response (SCR) serves as a physiological index of fearful arousal. Baseline SCR is collected during a two-minute period at the start of pre- and post-treatment assessments. At both BATs, anticipatory SCR is collected during a one-minute period immediately prior to starting the BAT, and SCR is then continuously recorded throughout completion of the BAT. In addition to SCR, number of steps completed (0 to 9) and repeated ratings of confidence, anticipatory distress, and maximum distress during the BAT serve as important indices of fear.

Self-reported stress, sleep quality, aerobic exercise, and knowledge of spiders are assessed as potential moderators of mental rehearsal and symptom change. Post-exposure ratings of surprise, US expectancy, and generalization of non-fear learning will additionally be evaluated as treatment mechanisms.

Inclusion Criteria:

• English-speaking
• Elevated score on Spider Phobia Questionnaire (SPQ)

Exclusion Criteria:

• Severe allergies to bees/spiders/insects