Generalization of Extinguished Fear to Untreated Fear Stimuli after Exposure

Abstract

Exposure therapy is highly effective in treating excessive fear related to specific objects and/or situations. However, patients with anxiety disorders often display a generalization of fear responses toward conceptually and perceptually related stimuli and situations. It is unclear whether the beneficial effects of exposure on fear reduction toward treated fear stimuli can extend to untreated fear stimuli. Here, we investigated whether basic principles of extinction generalization apply to exposure. Spider-phobic participants were randomly assigned to either two sessions of exposure treatment (n=23) with spiders or no-treatment (n=24). Prior to and after treatment, behavioral approach tests (BATs) were conducted to examine avoidance, fear and disgust responses toward the treated phobic stimulus (spider as the extinction stimulus). Likewise, BATs with the untreated fear stimulus (cockroach) were conducted to dissect the generalization of treatment effects. Treatment was highly effective in increasing approach behavior toward both treated and untreated fear stimuli. Generalization of treatment effects were evident on the behavioral (approach distance during the BAT), subjective (fear levels during the BAT) and psychophysiological level (heart rate during the BAT). However, a stronger decline in disgust was only evident for the treated fear stimulus. Notably, the herein attained generalization effects were not context-dependent. Hence, exposure therapy for spider phobia was effective in reducing fear of untreated stimuli which share common fear-evoking characteristics with spiders but were never presented during the respective exposure treatment. These findings provide clinical evidence for extinction generalization across different fear-evoking stimuli mediated via exposure.

Figure 1

Brief outline of the experimental design. Participants were assigned to a treatment or a no-treatment group. Only the treatment group engaged in two exposure sessions with spiders in context A. Therapy-induced changes in fear, disgust and avoidance of a house spider were assessed with behavioral approach tests (BATs) prior to (pre-assessment) and after treatment (post-assessment). Additional BATs with cockroaches (Blaptica dubia, 4 cm) as the untreated stimulus were conducted to assess extinction generalization. The order of BATs with spiders and cockroaches was counterbalanced across participants. The BAT with spiders was always conducted in the treatment room (context A), while the BAT with cockroaches was either conducted in the treatment room (ie, context A; treatment group: n=14; no-treatment group: n=12) or an adjacent, novel room (ie, context B; treatment group: n=9; no-treatment group n=12). Contexts A and B differed in size and shape, illumination, decoration, and furniture, as well as in size and color of the plastic containers used for BATs adapted from (Mineka et al, 1999; Mystkowski et al, 2002; Rodriguez et al, 1999).

Figure 2

Results of the BAT with spiders (treatment effectiveness: left; a) and cockroaches (extinction generalization: right; b) in terms of approach distance. Scores are displayed as Means±1 SEM. ***P<0.001.

Figure 3

Represents the reduction in fear (top; a and b) and disgust (bottom; c and d) from pre- to post-assessment (difference score) at the initial and final approach distance, separately for treatment effectiveness (left; a and c) and extinction generalization (b and d). Greater scores correspond to greater reduction from pre-to post-assessment. Scores are displayed as Means±1 SEM. ***P<0.001, **P<0.01.