Summary
Researchers explored how vegetarians and omnivores process and regulate their emotional reactions to vegetarian and nonvegetarian food cues, especially when hungry, by combining self-reported craving and affect ratings with neural measures from event-related potentials (ERPs). Twenty-four vegetarians and twenty-one omnivores viewed images of foods and were instructed either to simply watch them or to deliberately increase or decrease their appetitive value. As expected, vegetarians consistently rated meat and fish dishes as less desirable, less pleasant, and less arousing than omnivores did—and even less than they rated vegetarian foods—reflecting their subjective aversion and underlying beliefs. Interestingly, the neural data told a different story: ERP patterns during both passive viewing and cognitive reappraisal showed no meaningful group differences, implying that the brain’s early and late-stage processing of food cues was remarkably similar across vegetarians and omnivores. During regulation, both groups showed increased P300 and LPP amplitudes when trying to up- or down-regulate their responses and a decreased slow wave (SW) amplitude during down-regulation, indicating that reducing the appeal of food is more effortful and slower to implement than enhancing it, especially when hungry. Overall, the study suggests that while vegetarians consciously reject meat on a subjective and motivational level, their neural systems still register nonvegetarian foods as salient, highlighting a dissociation between personal beliefs and underlying motivational processing in the brain.
PMID: 31254550
DOI: 10.1016/j.appet.2019.104334
Abstract
The present study investigated cognitive reappraisal during exposure to vegetarian and nonvegetarian food cues in food-deprived vegetarian and omnivore participants. In particular, we were interested in clarifying the motivational meaning of the foods that vegetarians avoid, as revealed by self-reported food craving, valence, and arousal, as well as by ERP measures of neural processing during passive viewing and emotional regulation. Twenty-four vegetarians and twenty-one omnivores were instructed to either passively look at the pictures (Watch) or to change the appetitive value of the food (Increase or Decrease). In vegetarians, meat and fish dishes elicited lower desire to eat, pleasantness, and arousal during each condition as compared to both omnivores and vegetarian food. In contrast with the subjective data, no group differences were observed in any of the ERP measures, suggesting that similar neural processing of food-cues occurred in vegetarians and omnivores both during passive viewing and cognitive reappraisal. Concerning the late ERP effects during cognitive reappraisal, we found an enhancement of the P300 and LPP amplitudes during the Increase and the Decrease as compared to the Watch condition and a reduction of the SW amplitude in the Decrease as compared to Watch condition. These results suggest that in a food deprivation condition it is difficult to reduce the appetitive value of food stimuli, as this cognitive strategy appears to require greater effort and a longer time to be implemented with respect to up-regulation. Overall, our findings suggest that, in vegetarians, aversion towards nonvegetarian food prevails at the subjective level and is consistent with their personal beliefs. In contrast, at the neural level, the intrinsic motivational salience of this type of food is preserved.
Giraldo M, Buodo G, Sarlo M. Food processing and emotion regulation in vegetarians and omnivores: An event-related potential investigation. Appetite. 2019 Oct 1;141:104334. doi: 10.1016/j.appet.2019.104334. Epub 2019 Jun 26. PMID: 31254550.