Prior preferences interfere with the associative learning of food values.

Addressing unhealthy behaviors requires learning and implementing healthier options. Ecologically, we rarely undergo associative learning in naive environments; our prior preferences confound the learning process. This is perhaps especially true for food, for which we have strong, diverse preferences that may undermine the associative learning policies central to dietary interventions. This preregistered study investigates the flexibility of updating food values using a probabilistic reversal learning task where participants predicted outcomes associated with food stimuli varying in personal preference. The task alternated between "Congruent" blocks, reinforcing pre-existing associations, and "Incongruent" blocks, reversing them. Across independent cohorts (n = 279), we found that starting condition had a surprising, lasting effect on food-value association updating, with initial reinforcement of food-value priors potentiating learning inflexibility. Rigidity was further evident for liked food items, whereas disliked foods were adaptable to changing value associations. Additionally, associations with positive outcomes were learned more readily than negative ones, suggesting positive reinforcement may be more effective in informing food-based learning. These findings highlight the importance of reinforcement in shaping food-value associations and underscore its relevance to promoting healthier eating habits.