Operationalizing "trance". I: Rationale and research using a psychophenomenological approach.

Despite the popularity of the term "trance" among clinicians to describe the subjective effects associated with being hypnotized, heretofore there has been no means to operationalize that definition. The authors present a rationale and psychophenomenological method to operationalize the term "trance" in terms of (a) hypnotic depth, a quantitative measure of subjective trance assessed via a pHGS (predicted Harvard Group Scale) score, derived from regression analysis, and (b) "trance typology profiles," a qualitative differentiation of empirically derived (via cluster and discriminant analyses) categories of subjective trance experiences. The authors then discuss theoretical and clinical implications of this psychophenomenological approach for developing an operational definition of the concept of trance.