Author: Emily Matheson
Matheson, Emily, 2019 Cognitive Bias Modification in Eating Disorders: An Investigation into the Extent to which Appearance and Self-worth Related Biases Influence Risk for Eating Disorder Psychopathology, Flinders University, College of Education, Psychology and Social Work
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Eating disorder psychopathology is associated with a propensity to overvalue and prioritise stimuli related to appearance (weight and shape), food and self-worth. Historically food-related biases have been the focus of research, but recent attention has turned to the association between cognitive bias related to appearance and self-worth and eating disorder psychopathology and its risk factors. Despite robust evidence to support the relationship between these cognitive biases and risk for eating disorder psychopathology, investigations into the use of Cognitive Bias Modification (CBM) within eating disorders remain in its infancy, with only a handful of studies existing.
The purpose of this thesis was to expand on the preliminary research into CBM for two eating disorder risk factors, body dissatisfaction and negative affect. Initially, we conducted a pilot study, investigating the comparative efficacy of three novel interventions targeting the automatic processing system in young women (N = 91). We examined CBM targeting attention (CBM-A) for appearance, evaluative conditioning, and a visuospatial task, Tetris. CBM-A and Tetris were associated with significant improvements in appearance satisfaction, distress over feelings and negative affect, relative to the evaluative conditioning group.
The next study examined three CBM approaches (CBM-A for appearance, CBM-A for self-worth, and CBM-I for self-worth) relative to the active comparison condition, Tetris. We sequentially examined the degree to which attentional and interpretation bias for negative and positive appearance and self-worth related stimuli exacerbated and ameliorated body dissatisfaction and negative affect in an unselected sample of female undergraduate students (N = 67). All three CBM approaches effectively induced body dissatisfaction, but not negative affect. No CBM technique significantly improved state outcomes but moderation of intervention effects was detected. First, participants with higher levels of negative affect experienced a significant improvement in appearance satisfaction using Tetris. Second, women with high levels of dispositional body dissatisfaction, anxiety and depression in the CBM-A for appearance condition experienced greater improvements and reductions in weight satisfaction and negative affect, respectively. Third, women with high levels of anxiety in the CBM-I for self-worth condition experienced greater improvements in negative affect.
The third study focused exclusively on interpretation bias, comparing the existing CBM-I for self-worth paradigm to the newly developed CBM-I for appearance paradigm in modifying interpretation bias and symptomatology in young women (N = 123). The CBM for appearance protocol produced significant changes in the targeted bias, as well as significant improvements (associated with moderate effect sizes) in appearance satisfaction, relative to the CBM-I for self-worth and CBM-I control conditions.
The final study was a randomised controlled trial which examined the long terms effects of multi-session CBM-I for appearance, CBM-I for self-worth, and a CBM-I control condition on eating disorder-related bias and symptomatology in body dissatisfied women (N = 74). Completer analyses indicated that all three conditions changed positive bias; CBM-I for appearance (d = -3.50 [-.4.46 to -.2.53]) and CBM-I for self-worth (d = -1.2 [-1.83 to -.57]) significantly increased in bias while the CBM-I control condition significantly reduced positive bias (d = 1.07 [.33 to 1.82). Intent-to-treat analyses, however, showed no significant differences emerging between the interventions and the control condition. Changes to trait variables following one week of CBM-I home practice showed all three conditions had comparable effects on global eating disorder psychopathology, negative affect and clinical impairment at 2-week follow up.
In sum, the current findings give support to CBM interventions when conducted in an experimental setting, however we note that Tetris and control conditions for CBM-I hadsimilar effects to the CBM paradigms. We address limitations in the current methodology and discuss potential avenues for future research to investigate the application of CBM and other novel interventions in the prevention of eating disorder psychopathology.
Keywords: Cognitive bias modification, attentional, interpretation, body dissatisfaction, eating disorders
Subject: Psychology thesis
Thesis type: Doctor of Philosophy
Completed: 2019
School: College of Education, Psychology and Social Work
Supervisor: Professor Tracey Wade