Abstract
In today's market, mystery boxes (where the contents are uncertain) introduce uncertainty concerning the outcome, offering the consumer the chance to receive one of several possible foods. However, the role of uncertainty-of-outcome induced in food preference is unclear. This research investigated how uncertainty-of-outcome affects food preference for high- versus low-calorie food products, and its cognitive and neural mechanisms. Fifty-eight participants completed a binary-choice task, deciding between a certain option (a known food) and an uncertain option (an unknown food hidden in a mystery box), and rated the expected tastiness (subjective value) of each food. The participants exhibited a stronger preference for uncertain options in the low- (vs. high-) calorie case. Using the drift-diffusion model, the drift rate was higher in the low- (vs. high-) calorie condition. Moreover, a larger frontal N2 amplitude and smaller frontal P3 and LPP amplitudes were detected in the low- (vs. high-) calorie condition during the binary-choice task. Besides, frontal LPP amplitudes were negatively correlated with drift rate, suggesting that more cognitive effort was required to accumulate evidence to make a decision. Additionally, high-calorie foods elicited larger frontal alpha event-related desynchronization than low-calorie foods, thus suggesting participants require more evidence and effort in value comparison during the decision-making. This research highlights how uncertainty-of-outcome enhances the reward value of food, especially low-calorie foods, and thus impacts food preference, providing insights for developing marketing and public health strategies.