NOVEMBER 2003, VOLUME 31, NUMBER 2, Abstract 2
A Structural Analysis of the Harvard Group Scale of Hypnotic Susceptibility: a Generation On
John P. Sjostedt, The University of Newcastle
John D. C. Shea, The University of Newcastle
Through a series of six studies during the period 1996-2001, a sample of 894 predominantly first-year Psychology students from the University of Newcastle, with an average age of 23.1 years (SD = 8.0), participated in an investigation of the structure of the Harvard Group Scale of Hypnotic Susceptibility: Form A (HGSHS). Ages ranged from 17 to 60 years and there were 694 females (M = 23.0 years, SD = 7.9) and 156 males (M = 24.6 years, SD = (9.1); a group of 44 students failed to record age and sex details for reasons of confidentiality. To investigate dimensional complexity and to broadly replicate aspects of the McConkey, Sheehan, and Law (1980) study into the factorial structure of the HGSHS, a tetrachoric correlation matrix was formed from dichotomously rated HGSHS items to simulate effects of a continuous rating scale. Principal Components (PCA) and Maximum Likelihood analyses (MLA) were performed to determine scale structure. It was hypothesised that the complexity of hypnosis would be reflected in the multidimensional structure of the HGSHS. It was also expected that the structure of the HGSHS would conform to that found in the MCConkey et al. (1980) study. Very broadly, this was found, with the MLA solution proving to be more interpretable by comparison with PCA. Theoretical arguments concerning the hypothesised complex, multidimensional nature of hypnosis (Hilgard, 1965) were discussed in relation to Coe and Sarbin’s (1971) role-skill/item difficulty continuum hypothesis.