Hypnotizability, Dissociation and Three Factors of Eating Behaviour

Concepts such as hypnosis and dissociation have attracted increasing interest within dietary disorder research, especially in the investigation of bulimia nervosa and bulimic tendencies. A number of studies have revealed that, compared with agematched controls, individuals expressing bulimic tendencies demonstrate elevated levels of hypnotizability (e.g., Pettinati, Horne & Staats, 1985; Groth-Marnat & Schumaker, 1990; Barabasz, 1991; Kranhold, Baumann & Fichter, 1992; Covino, Jimerson, Wolfe, Franko & Frankel, 1994) and increased dissociative capacity (e.g., Sanders, 1986; Torem, 1986; Demitrak, Putnam, Brewerton, Brandt & Gold, 1990; McCallum, Lock, Kulla, Rorty & Wetzel 1992; Vanderlinden, Van Dyck, Vandereycken & Vertommen, 1993; Rosen & Petty, 1994). Despite evidence that dissociative and hypnotic capacities are both greater in bulimics, measures of these two capacities are themselves only modestly correlated (Nadon, Hoyt, Register & Khilstrom, 1991; Frischholz, Braun, Sachs, Schwartz, Lewis, Shaeffer, Westergaard & Pasquotto, 1992; Oakman, Woody & Bowers, 1996) and may represent the operation of different, yet related, psychological processes. Given that hypnosis and dissociation are only loosely correlated and, in view of the complex nature of bulimic aetiology, it appears likely that hypnotic and dissociative mechanisms may operate on different psychological aspects of this type of eating disorder. The use of specific psychological measures of eating behaviours and attitudes is helpful in constructing theoretical frameworks that may relate aspects of bulimic tendencies to hypnotic and dissociative mechanisms. Unfortunately, few studies have as yet identified specific behavioural and psychological patterns, relating to hypnotic and dissociative capacity, which are associated with bulimic behaviour and bulimic tendencies. Groth-Marnat and Schumaker (1990) did find interesting associations between hypnotizability and concerns over weight and fat, suggesting the operation of social factors, possibly moderated by hypnotic capacity. Similarly, Wybraniec and Oakley (1996) found moderate correlations between hypnosis in a waking context and cognitive aspects of dietary restraint. In terms of dissociative capacity Rosen and Petty (1994) found high to moderate correlations in a college population between both affective and loss-of-control aspects of dissociation and a wide range of eating disordered behaviours and attitudes, including bulimic tendencies.