Investigating the Origins of Partisanship: What Motivates Children to Preferentially Endorse Their Ingroups’ Claims?

Adults often endorse empirical claims along partisan lines, sometimes agreeing with their ingroup even when the evidence suggests otherwise. A developmental approach can clarify the motives underlying this phenomenon by examining it early, before political identities are entrenched. We tested two possible motives underlying children’s partisan endorsement: Do children endorse their ingroup’s empirical claims because they believe the ingroup is a reliable guide to truth (an epistemic motive), or because public agreement signals loyalty and strengthens group bonds (an affiliative motive)? Study 1 (N = 98; ages 5–7) replicated the basic partisanship phenomenon in childhood: Children assigned to a minimal group endorsed their ingroup’s claims more often than children in a no-group control condition, establishing that group membership provides a partisan “boost” beyond what perceptual evidence alone would warrant. Studies 2 and 3 then probed motives in complementary ways: Study 2 (N = 208; ages 6–9) removed the social-audience benefits of endorsing the ingroup by having children respond privately, whereas Study 3 (N = 172; ages 6–9) increased the value of accuracy by incentivizing correct judgments. Partisan endorsement was absent under private responding and significantly reduced by accuracy incentives. Overall, the pattern across studies was more consistent with an affiliative motive than an epistemic one: Children’s partisan endorsement appears to function as public signaling of group support rather than solely as a reflection of epistemic trust in the ingroup. These findings speak to the developmental origins of partisan cognition and potential levers for encouraging evidence-based reasoning.