To eat or not to eat. The effects of expectancy on reactivity to food cues.

Cue reactivity may be determined by the ability of cues to evoke expectations that a reward will be imminently received. To test this possibility, the current study examined the effects of manipulating expectations about the receipt of food (pizza) on self-reported and physiological responses to pizza cues, and attentional bias to pizza pictures. It was predicted that expecting to eat pizza would increase salivation, self-reported measures of motivation and attentional bias to pizza cues relative to conditions where there was no eating expectancy. In a within-subjects counterbalanced design, 42 hungry participants completed two pizza-cue exposures in a single experimental session during which their expectation of consuming the pizza was manipulated (i.e., expectancy of eating imminently vs. no eating expectancy). They also completed a computerised attentional bias task during which the probability of receiving pizza (0%, 50% or 100%) was manipulated on a trial-by-trial basis. Participants showed reliable increases in hunger and salivation in response to the pizza cues, as well as a bias in attentional maintenance on pizza pictures. However, these responses were not influenced by eating expectancy. Contrastingly, expectancy did influence early attentional processing (initial orientation of attention) in that participants directed their first gaze towards pizza pictures more often on 100% and 50% probability trials relative to 0% trials. Overall, our findings indicate that exposure to food cues triggers appetitive responses regardless of explicit expectancy information. Methodological features of the study that may account for these findings are discussed.