Abstract
Research has indicated an effect of obesity on cognitive performance but there has been limited research considering how individual differences in eating behaviour are related to variation in cognitive processes. Differences in cognitive performance influence an individual’s ability to undertake behaviour change or maintain healthy behaviours. This thesis addressed a current gap in the literature by assessing the effect of Restraint, Emotional and External eating behaviour on the cognitive processes involved in undertaking causal reasoning judgements and the inhibition of distraction by food images. Study 1 (N=176) examined how individual’s causal conditional reasoning (CCR) performance varied dependant on whether the reasoning tasks was based on general or obesity causal relationships. Participants made more accurate, logical reasoning decisions when undertaking obesity CCR tasks compared to general CCR tasks. However, individuals high in restraint did not show the same increase in reasoning ability for obesity tasks, but their performance for general tasks did not differ. Study 2 (N=110) replicated key findings however, increased levels of restraint were associated with detrimental CCR performance across both conditions. Study 3 (N=83) confirmed that a participants automatic belief in the causal relationships drove their CCR responses more than controlled, logical processing. Study 4 (N=31) was the first of three flanker studies examining ability to inhibit distraction by food pictures. Results showed emotional eaters were slower to respond to target pictures, with external eaters displaying a significant reduction in distraction for palatable flanking pictures. Study 5 (N=47) compared individual differences in cognitive control modulation (CCM) for food and non-food pictures. Results showed emotional and external eaters slower to respond to food pictures, with emotional eaters demonstrating significantly greater levels of CCM for food pictures only. Study 6 (N=48) found when required to simultaneously process food and non-food pictures, participants respond more strongly to differences in valence of target stimuli. In addition participants were more distracted when responding to sweet targets foods. In summary, the thesis suggest a relationship between eating behaviour traits and cognitive processing when undertaking causal reasoning and inhibiting distraction by food pictures. The synthesis of results indicates emotional and external eating behaviour influences automatic cognitive processes more strongly, with increased levels of restraint influential on controlled cognitive processes. The implications of findings on the design and implementation of behaviour change or maintenance programs is apparent.