Cognitive and Behavioral Effects of Participant Modeling: A Comparison with an Equally Credible Placebo

Thirty-eight snake phobic subjects were given one session of either participant modeling, an initially equally credible placebo treatment, or experienced a no-treatment control condition. Both the subjects in the participant modeling and placebo treatments showed significant changes on both behavioral and self-report indices, with the participant modeling subjects evidencing significantly greater improvement across conditions. Between group differences were not obtained at a four week follow-up, possibly as a result of shortness of treatment and differential attrition. Although initially equal across treatments, credibility increased significantly for the participant modeling group and stayed virtually the same for the placebo group. Differential concepts of credibility are postulated, with the observed increase in credibility attributed to self-observed behavior change for recipients of participant modeling. Participant modeling also produced higher and stronger levels of perceived self-efficacy.