Development and analysis of a scale of suggestibility

Nowdays hypnosis is becoming a technology increasingly used in several area s of basic and applied psychology. However, it is not clear what is the psy chological variable that causes the differences observed between subjects w ith respect to the ability to be hypnoptized. The main goal of this paper i s to construct a rigorous questionnaire in order to assess the susceptibili ty of people to hypnosis. A sample of 102 participants were used (57 men an d 45 women). The ten items questionnaire built has a high internal consiste ncy, measured by means of the Coefficient Alpha (alpha = 0.97). The factor analysis oi the items showed that susceptibility to hypnosis, as measured b y this questionaire, has a unidimensional structure. Responses to the quest ionaire items fit the two-parameter Item Response Theory logistic model. Us ing logistic regression analysis it was found that the questionaire has a h igh validity to predict the easiness of subjects to be hynoptized, with a r ate of correct subject classification above 90%. No gender differences in s usceptibility to hypnosis were found.