Effects of Spicy Food on Sense of Fairness: Mediating Effects of Aggression and Pathogen Avoidance

Spicy food consumption is prevalent worldwide, yet its psychological and behavioral impacts remain underexplored compared to basic tastes like sweet, sour, salty, bitter, and umami. The present research aimed to investigate the effects of spicy food preferences and consumption on individuals' sense of fairness, with aggression and pathogen avoidance considered as potential mediators. Two behavioral studies using the Ultimatum Game were conducted to examine these relationships. Study 1 found that individuals with a preference for spicy food were more likely to reject unfair offers and accept fair offers, mediated by trait aggression and trait pathogen avoidance, respectively. In Study 2, immediate consumption of spicy food led to a higher rejection rate of unfair offers compared to non-spicy food consumption, an effect mediated by increased state aggression. However, no significant differences in fair offer rejection rates were observed between the spicy and non-spicy conditions, and no significant mediation effects of situational pathogen avoidance were detected. These findings suggest that spicy food enhances sensitivity to unfairness-likely by elevating an individual's acceptance threshold-an effect primarily driven by aggression. This research provides novel insights into how sensory experiences shape social decision-making and fairness judgments.