Norm conflict and ingroup bias in children's polite and altruistic lies.

Prosocial lying supports children's social functioning, yet different types of prosocial lies may not follow the same group patterns. This study examined 7-, 9- and 11-year-old children's polite and altruistic lies towards ingroup and outgroup recipients and the role of theory of mind (ToM) in these behaviours. Polite lies showed a group-general pattern: children told them equally across group lines, independent of ToM. In contrast, altruistic lies displayed a marked ingroup bias that strengthened with higher ToM levels. These findings indicate that prosocial lies are context-sensitive and governed by distinct social-cognitive processes. By revealing that ingroup bias extends to prosocial behaviours involving tension between honesty and altruism, the study clarifies how social and moral considerations and group processes jointly shape the development of children's moral reasoning.