Psychometric Properties of the Interpersonal Outcome Expectancies for Thinness (IOET) Scale: Evidence for Validity, Reliability, and Utility in the Study of Eating Disturbances in Females

Introduction: Interpersonal context is believed to represent a powerful factor that often fosters and sustains eating disturbances in females. The present study focused on the development of a measure tapping into positive interpersonal expectancies predicated on being thin believed to be positively involved in eating disorders in females, namely, the Interpersonal Outcome Expectancies for Thinness (IOET). Method: In Study 1, a total of 361 U.S. female college students completed the IOET for factor analysis. In Study 2, to assess for construct validity, an independent sample of 184 U.S. female college students completed a test battery including the IOET and measures of eating attitudes and disturbances, positive and negative affectivity, and general optimism. Results: In Study 1, results from an exploratory factor analysis indicated a one-factor solution for the IOET accounting for 76.70% of the total variance. In Study 2, the IOET was found to possess good test-retest reliability (6-week) in a subset sample of U.S. female participants. Moreover, in support for construct validity, we found IOET scores were positively associated with scores on measures of eating disturbances (e.g., bulimic symptoms) and negative affectivity. Additionally, IOET scores were negatively associated with scores on a measure of general optimism. Finally, in support of utility, the IOET was found to add incremental validity to the prediction of eating disturbances, even after accounting for general optimism and affectivity. Discussion: The present findings provide promising evidence for the validity, reliability, and utility of the IOET as a measure of a maladaptive cognitive schema associated with eating disorders in females. Implications for the theory and clinical assessments were discussed.