Belonging to a group with shared ideology leads preschool children to resist revising their beliefs despite disconfirming evidence

Shared beliefs can bring people together but may motivate prioritizing group affiliation over facts supported by evidence. Indeed, affiliation with a group whose membership is tied to shared beliefs (i.e., ideology-based groups) has led adults to endorse and maintain false beliefs. We demonstrate that this resistance to revise beliefs that form the basis of group membership has its origins in childhood. In three studies, 4- to 5-y-old children ( N = 192 ) endorse a claim about a novel causal system and subsequently join a group that shares their endorsement. Children randomly assigned to a focal Belief-contingent condition learn that their membership in the group is based on this claim, framed as a shared belief. We contrast this with conditions where group members hold the same shared belief, but this belief is not a condition for group membership (Experiments 1, 2, and 3), and where group members hold to the same claim framed as a “guess” (Experiment 2). After joining a group, children see evidence that their initial endorsement was incorrect and then have an opportunity to revise based on the new information. Only when group membership was contingent on the shared belief did children hold on to (and act on—Experiment 3) their initial incorrect endorsement. These findings suggest that the affiliative power of ideology has developmental roots; even in our earliest years, affiliative motives override truth-seeking and rationality. Thus, our early-emerging motive to identify with groups may underlie later cases of evidence denial and polarization.