The effect of hunger and state preferences on the neural processing of food images

Visual information plays a key role in guiding food-related decisions. While previous studies have shown that features such as calories and naturalness are encoded by the brain, upon simply seeing the stimuli, it remains unclear how this encoding is shaped by the observer's current state. In this study, we explore the effect of 1) hunger state, 2) task relevance, and 3) current individual preference on the processing of visual food information. Participants (N = 23) underwent two EEG sessions: one after fasting overnight and another after eating normally. During each session, participants did two separate tasks, one where the stimuli were task-relevant and one where attention was distracted away. We used multivariate analysis methods to assess the impact of hunger on the representation of food-related features, and to determine the time-course of information related to food flavour, personal appeal, and arousal, across both tasks. Results showed that information about edibility (food vs non-food object), food identity (e.g., hamburger vs pizza), flavour profile, or personal appeal and arousal was not influenced by the hunger manipulation. Flavour was represented regardless of attentive state, whereas personal appeal and arousal information emerged later and were only observed when the food was task-relevant. We found that food appeal and arousal encoding were more closely aligned with behavioural ratings within rather than between sessions, suggesting the nature of the encoding was driven by current state. The study provides insights into how personal preferences and physiological states influence the representation of food information in the brain.