Systematic desensitization: distribution of practice and symptom substitution*

Six spider-fearing female undergraduates were given relaxation training plus systematic desensitization with 2-3 treatment sessions per week (Group S: spaced practice); 6 were treated in the same manner but with sessions several times a day (Group M: massed practice); and 5 were given relaxation training plus 2-3 "placebo" sessions a week (Group P: placebo). Groups S and M both showed a relative reduction in spider fear, and appeared to maintain it over a variable follow-up period. Group S showed a decrease in general anxiety but Group M did not. A 3-level self-report stimulus generalization scale was constructed by identifying fears judged highly similar, slightly similar, and dissimilar to spider fear. Treated Ss showed fear reduction at all levels when compared to untreated non-fearful control Ss, providing evidence against the "symptom substitution" hypothesis.