Developmental patterns and computational mechanisms of school-aged children’s fairness-related decision making under social comparison

The developmental patterns and computational mechanisms underlying the impact of unfair offers and social comparisons on school-aged children's fairness-related decision making remain unclear. To address this, we recruited 190 children aged 8 to 12 years (52.1% female) in a multi-responder ultimatum game. Results revealed an age-related decline in children's tendency to reject unfair offers, partially mediated by emotions, alongside a slight increase in rejecting inferior social comparisons. Computational modeling identified two distinct motivations guiding children's rejection behavior: inequity aversion and inferior social comparison avoidance. Furthermore, there was significant variability in responses to superior social comparisons, with some children displaying aversion and others seeking. Our refined model enhances the explanatory power of inequity aversion theory in complex multi-player social scenarios, validating and refining existing theories. In addition, the exploration of superior social comparison tendencies reveals individual heterogeneity, enriching our understanding of children's social comparisons. These findings contribute to elucidating the developmental patterns and internal mechanisms of children's socialization processes, offering implications for promoting their social adaptation and mental health.