Age differences of responders' decision-making in disadvantageous and advantageous inequality contexts in the ultimatum game: The role of social value orientation

The Ultimatum Game (UG) is a classic paradigm used to study fairness-related decision-making. While responders' rejection of disadvantageous inequality in the UG is known, responses to advantageous inequality and the role of social value orientation (SVO) remain unclear. This study involved 59 children of 6–8 years, 69 children of 10–12 years, 59 adolescents of 14–15 years, and 52 adult college students. It explored responders' decisions in three offer contexts, including disadvantageous inequality, equality, and especially advantageous inequality, and the role of SVO. Results showed that SVO shifted from pro-self to pro-social and back to pro-self with age. Offer contexts moderated the effect of age on rejection rates, notably advantageous inequality, reflecting age differences in social preferences. Children accepted such offers for self-interest, adolescents rejected for inequality aversion, and college students accepted for joint gain maximization. SVO mediated the effect of age on rejection rate only in advantageous inequality contexts. The results indicate diverse motivation and decisions across scenarios, tied to age and SVO. Pro-social orientation's significance in advantageous inequality aversion is highlighted. Overall, these findings suggest that responder traits and developmental stages jointly shape economic decisions, especially regarding advantageous inequality.