The Inhibitory Spillover Effect and its application to eating behavior

Abstract

Overweight and obesity are prevalent worldwide and have numerous negative physical, mental and social consequences. Thereby, impaired inhibitory capacity is central for the increase of overweight and obesity in an obesogenic environment which facilitates weight gain. Both classic weight loss programs comprising behavioral or lifestyle changes as well as specific inhibitory control trainings demonstrate only small effects. The inhibitory spillover effect was recently introduced as an approach to increase inhibitory control by the unintentional transfer of activated inhibitory control in an induction task to a simultaneously executed outcome measure. Several findings showed various transmissions of inhibitory capacity, for example from increased bladder pressure to performance in a concurrent Stroop task as classic measure of inhibitory control, or from activated attention control to contemporaneous choices in a self-control scenario. Although feasibility of the inhibitory spillover effect already has been demonstrated, magnitude of the effect and of different induction methods is only known to a limited extent. Furthermore, research about the inhibitory spillover effect in the field of eating behavior is scarce and confined to participants with normal weight. Therefore, the aim of the present dissertation is to evaluate the magnitude of the inhibitory spillover effect and its induction methods as well as the application of the inhibitory spillover effect to influence eating behavior in participants with overweight and obesity. Study 1 aggregates findings of experiments that, intentionally and also unintentionally, comprised the inhibitory spillover effect, revealing effect sizes for the inhibitory spillover effect in general as well as for different induction methods. Experiments in the studies 2 and 3 examined the application of the inhibitory spillover effect through different cognitive induction methods to change concurrent food intake in a bogus taste test or reaction to food stimuli in a stop-signal task in participants with overweight and obesity, compared to participants with normal weight. In both studies, additional neutral conditions were employed. Literature research in study 1 revealed 15 studies incorporating the inhibitory spillover effect. Results showed a small but substantial and robust effect for the inhibitory spillover effect in general as well as small to high effects for physiological, attention, and cognitive induction, while motor induction had no effect. The effort to increase inhibitory control whilst eating by means of simultaneous thought suppression as cognitive induction of the inhibitory spillover effect in study 2 revealed no interaction between weight group and condition as well as no effect for weight group. However, a significantly heightened food intake was observed in the condition with inhibitory spillover effect compared to the neutral condition, being in opposition to the hypothesis. A rebound effect of the applied thought suppression may be central for this result, highlighting possible side-effects and boundaries of induction methods. Study 3 used a cognitive priming with control-related words to influence either food intake in a simultaneous bogus taste test or reaction to food-stimuli in a concurrent stop-signal task, but revealed no significant differences between conditions or groups after controlling for age differences. In this, an insufficient induction procedure as well as a mismatch between induction procedure and outcome measure may be relevant for the results. The findings of the present dissertation expand theoretical and practical knowledge about the inhibitory spillover effect by a lot through comprehensive meta-analytic findings of already existing data but also with the execution of three sophisticated and well-designed experiments which apply the inhibitory spillover effect in the field of overweight and obesity for the first time. Results of the studies accelerate research about the inhibitory spillover effect and provide valuable new insights concerning possible opportunities and limits of the inhibitory spillover effect as well as further starting points for future research, which are also discussed in this dissertation.