Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Dr. C. Richard Spates

Second Advisor

Dr. Lisa E. Baker

Third Advisor

Dr. R. Wayne Fuqua

Fourth Advisor

Dr. Robert A. McArthur


Previous research with non-humans, and humans to a lesser degree, suggest the endogenous opiate system is at work to assist an organism in times of pain or stress. One-session exposure treatment is an effective treatment for specific animal phobia and entails modest degrees of stress during implementation. At the present time, the mechanisms at work that facilitate the success of this intervention have been incompletely investigated. The focus of the present study was to determine whether the endogenous opiate system is activated during the treatment of persons with specific animal phobias. In a double-blind investigation, 15 individuals with specific animal phobia (i.e., snakes, spiders, mice, or rats) were randomly assigned to one of three groups: naltrexone plus standard treatment, placebo plus standard treatment, or standard treatment alone. Naltrexone, an opiate antagonist, is known to block opiates from binding to their receptors and thus its use in one experimental condition in this investigation would rule out the hypothesized role of endogenous opiates. It was hypothesized that one-session exposure treatment would be less effective for the naltrexone plus standard treatment group in comparison to the other two groups as assessed by self-report, behavioral, and physiological measures, and completion rates. While the primary intervention was effective across conditions, there were no significant differences between the groups on any dependent measures, which suggests a reduced role if any of the endogenous opiate system in explaining the effects of this treatment protocol.

Access Setting

Dissertation-Open Access