The efficacy of the Waterloo-Stanford Group Scale of hypnotic susceptibility: form C.

This study explored whether the Waterloo-Stanford Group Scale of Hypnotic Susceptibility Form: C (WSGC) approximates the predictive power of the individually administered Stanford Hypnotic Susceptibility Scale: Form C (SHSS: C). Seventy-one undergraduates were administered the WSGC in a group setting and then tested individually on the SHSS: C. The participants were then hypnotized and tested on four types of targeted hypnotic behaviors sampled from the Revised Stanford Profile Scale of Hypnotic Susceptibility: I & II (RSPSHS: I & II). The following four factors were chosen: (a) cognitive distortion; (b) positive hallucination; (c) negative hallucination, and (d) dreams and regression. The items from these factors were matched on difficulty level. A series of multiple regression and logistic regression analyses were performed. The Waterloo: C was found to match the SHSS: C on predictive power for only one of the four hypnotic factors: "dreams and regression." On the other three factors, the SHSS: C was clearly superior in predictive efficacy. These results mirror previous research (Kurtz & Strube, 1996) that examined other group scales of hypnotic susceptibility in relation to the individually administered SHSS: C. In general, group scales such as the WSGC are poor substitutes for the SHSS: C.