The relationship between credibility of therapy and simulated therapeutic effects

The effect of variable credibility of treatment procedures on avoidance behavior was assessed in three studies. Snake-fearful Ss were pretested and then presented with descriptions of, and rationales for, various therapy and placebo conditions. Subsequently, the Ss were asked to assume that they had received 5 weeks of therapy by the described treatment, to simulate its effects on the posttest, and to rate its credibility. While one experiment demonstrated that Ss will simulate more positive treatment outcome under preferred treatment conditions, no mean differences in outcome were found among placebo and therapy rationale conditions in the two other experiments. Simulated therapy response and rated credibility were, however, significantly correlated in all three studies.