The impact of motivational states on hedonic snack consumption and implications for disordered eating

Abstract

The research presented in this thesis explores the role of regulatory focus (promotion versus prevention foci), and related attentional scope (global versus local processing), in influencing people's consumption of pleasurable snack food in the absence of physical need - an eating style that is contributing to growing rates of obesity worldwide. In the first two studies, male and female undergraduates were invited to help themselves to a bowl of M&Ms while they engaged in a global processing, local processing, or control task. Attempts to manipulate local processing using a rhyming task were successful in both studies, evidenced by significant increases in left hemispheric activation from baseline. This local processing, as predicted, had an inhibitory effect on participants' M&M consumption relative to the control task in both studies, which was interpreted as a regulatory misfit between the food type and the scope of attention. Compared to local processing, the manipulation of global processing proved more difficult. In Study 1, mental rotation was employed as the global processing task, however, against prediction it failed to significantly activate the right hemisphere or facilitate M&M consumption. In Study 2, mental rotation was replaced with insight problem-solving which showed a trend (although non-significant) towards right hemispheric activation and greater M&M consumption relative to the control task, suggestive of a fit between the food type and the attentional scope.

Prompted by evidence that pleasurable snack food may serve a distinct safety/protective function for eating disordered individuals who engage in regular binge eating, the second two studies of this thesis investigated whether promotion and prevention foci impact the snack consumption of these individuals differently. In Study 3, non-clinical female university students were invited to eat M&Ms as they worked on a set of promotion focus, prevention focus, or control mazes. As predicted, consumption by no/mild binge eaters (based on a sample split of scores on the Binge Eating Scale) was substantially facilitated by the snack-compatible promotion focus mazes. However, against prediction, the supposedly snack-incompatible prevention focus mazes failed to have an inhibitory effect. As hypothesised, moderate binge eaters exhibited a very different pattern of results. Specifically, they showed a significant increase in M&M consumption in response to the prevention focus mazes, and a slight (but non-significant) decrease in consumption in response to the promotion focus mazes, compared to no/mild binge eaters primed with the same foci. These findings were replicated by Study 4 which pre-screened prospective participants to ensure a greater proportion of clinically significant cases of disordered eating. Using a "taste test" cover story, Study 4 also extended Study 3 by adding a follow-up "tasting" period in order to examine the longevity of the foci's effects on consumption. The results demonstrated that the effects are transient. Regardless of the level of disordered eating, the best predictor of snack consumption at the second tasting period was not regulatory focus, but the amount consumed at the first tasting period.

Consistent across all four studies, the effects of regulatory focus and attentional scope on snack consumption were not associated with changes in hemispheric activation or mood. Furthermore, conscious desire to eat the snack remained unaffected despite impacts on consumption, suggesting that the manipulations were leading participants to approach or avoid the tasty snack at an unconscious or automatic level. In conclusion, this thesis points to motivational and attentional strategies for curbing overeating and binge eating that are highly contingent on where an individual lies on the disordered eating continuum. Show more