Bias in interpretation of ambiguous scenarios in eating disorders.

Eating disorders appear to be associated with biased information processing, particularly in judgments involving the self. This study investigated three possible biases. Patients with anorexia nervosa, patients with bulimia nervosa and female controls completed questionnaires designed to assess interpretation of ambiguous scenarios with either a negative or positive outcome. When events had a negative outcome the patients responded spontaneously to open-ended questions with a weight and shape interpretation. Later, in a forced-choice format, they selected the weight and shape interpretation in preference to interpretations not connected to weight and shape. In both open-ended and forced-choice format this bias was specific to judgments involving the self. When events had a positive outcome the bias was reversed and, in the two formats, it was found only in judgments involving others. In both cases, i.e. for negative self-referent events and for positive other-referent events, patients predicted that weight and shape explanations were more likely. Both groups of patients estimated that negative outcomes involving the self would be more costly. The patients with bulimia nervosa also estimated that positive outcomes involving the self would be more beneficial. Theoretical explanations and clinical implications are discussed.