The emotional decision maker: Exploring the role of affect in sweet-food choice

Obesity is now described as a pandemic (Hu, 2013) and a strong association has been identified between sugar consumption and excessive weight gain (e.g. Te Morenga, Mallard & Mann, 2013). Yet difficulty in establishing the factors driving this relationship leaves a dearth of research investigating causal mechanisms behind this global crisis (Lean, Astrup & Roberts, 2018). Food choice has been linked with cognitive processes involved in decision making (Peters, 2009), which in turn, has been linked with affect, i.e. mood and emotion (Lerner, Li, Valdesolo & Kassam, 2015). The aim of this thesis was therefore to explore the way in which both state and trait affect influence impulsive, sweet food decision making across three studies. As hypothesised and supported by affective regulation theory (Gross, 1998), results showed that as laboratory-induced mood (i.e. state affect) moved from positive to negative, the likelihood of choosing a chocolate reward over a non-food/neutral reward increased. This finding was conclusively evident when controlling for other factors such as chocolate craving in Study 2, ultimately highlighting the complex influence of affect on sweet food choice. Following this initial choice in Studies 1 and 2, subsequent hypotheses concerning impulse and self-control were not wholly supported as participants in both mood conditions were more likely to make impulsive decisions than exercise self-control. While affective regulation theory also explained those in negative moods making impulsive choices, an integrative framework was put forward to explain those in positive moods displaying the same behaviour (Andrade, 2005). In Studies 2 and 3 a willingness-to-pay (WTP) task was included to explore the relationship between state and trait affect and economic decisions concerning chocolate and high-sugar foods. While laboratory-induced mood did not predict WTP prices in Study 2, decreasing positive affectivity (i.e. trait affect) was found to significantly predict higher WTP prices for chocolate and high-sugar items, as hypothesised in Study 3. Reduced positive affectivity has been linked with symptoms of depression (Watson, Clark & Carey, 1988) which, in turn, is associated with an increase in desire for chocolate and sweet foods (Lester & Bernard, 1991). These results therefore provided robust evidence that higher spending for sweet items is connected to the absence of positive affectivity rather than presence of negative affectivity. Finally, increasing chocolate craving was found to significantly predict choices and increasing WTP prices for chocolate items in Studies 2 and 3. The potential parallel between chocolate and substances more commonly associated with addiction is discussed, together with the broad, practical implications of all findings in the context of sweet food choice and obesity.