Cognitive processes in anorexia nervosa and bulimia nervosa
The series of studies reported in this thesis aimed to improve our knowledge of the cognitive disturbance in anorexia nervosa and bulimia nervosa. Techniques from experimental cognitive psychology were used to test predictions made by cognitive theories of eating disorders. In the first study, subjects performed three tasks related to eating, weight and shape and self-statements were measured using concurrent verbalisation and a selfreport questionnaire. Compared to dieters and non-dieting controls, patients with bulimia nervosa showed greater concern with weight and appearance while patients with anorexia nervosa showed greater concern with eating. In the second study, using an adaptation of the Stroop colour-naming task, patients with eating disorders showed greater selective processing of information related to eating, weight and shape than normal, non-dieting controls and normal dieters. In the third study it was found that this disturbance was more closely related to measures of the specific psychopathology of eating disorders rather than to measures of general psychopathology. In the fourth study information processing before and after treatment was compared. As predicted by cognitive theories, selective processing appeared to be related to the emotional salience of the clour-named words rather than to patients' familiarity with the issues represented by these words. In the fifth study information processing before and after three different psychological treatments for bulimia nervosa was measured. No support was found for the hypothesis that cognitive behaviour therapy operates through mechanisms specific to this treatment. Contrary to predictions, in the sixth study, when colour-naming was measured at the end of treatment and at 12 month follow-up, selective information processing did not predict relapse in symptoms of bulimia nervosa. Finally, a seventh study, which manipulated attitudes to eating, weight and shape experimentally, found evidence for a causal relationship between these attitudes and disturbed eating behaviour. Methodological issues, and the clinical and theoretical relevance of the research findings, are discussed.