Development of synchrony‐dominant expectations in observers

Movement synchrony is an essential feature of rituals and collective displays around the world. Previous studies have shown that synchronous movements increase observers’ perceived group entitativity and fighting capacity in agonistic contexts; however, little is known about the developmental roots of synchrony‐dominant attributions. In this study, adult participants (Exp 1), 5‐ to 6‐year‐old children (Exp 2) and 7‐ to 8‐year‐old children (Exp 3) predicted outcomes of zero‐sum conflicts between two groups of animated agents after each group exhibited either synchronised or non‐synchronised movements. Predictions were made for conflicts between two individual members from different groups (individual‐conflict condition) and between all members of the two groups (group‐conflict condition). Results showed that none of the participant groups showed a synchrony‐dominant preference in the individual‐conflict condition. In the group‐conflict condition, most adult participants expected the groups exhibiting synchronised movements to be socially dominant. Although 5‐ to 6‐year‐old children did not show more biased expectations than can be accounted for by chance, adult‐like synchrony‐dominant preference was found in 7‐ to 8‐year‐old children. Moreover, justifications of the synchrony‐dominant expectation in both adults and 7‐ to 8‐year‐old children showed that this expectation was driven by the perceived entitativity of the synchronous group. These findings show that the expectation of group dominance based on synchronous movements is strongly developed in school‐age children, explaining the developmental origins of intergroup attitudes as well as the cognitive mechanisms children employ when making judgments in intergroup contexts.