In two experiments, we experimentally manipulated people's subjective opinions about new wellness trends using positive clips from publicly available YouTube videos. Participants spontaneously judged novel statements that were consistent with their new opinion to be factual, despite the fact that they had encountered no direct evidence for any of the statements. Belief change was stronger among participants whose opinions were more swayed by the manipulation. Positive opinions also biased participants' curiosity such that they were highly motivated to learn more about opinion-congruent statements. In Study 2, participants reported false memories for the opinion-congruent statements within the video. These results illustrate the primary role of subjective opinions in belief formation about objective truths, and suggest that the eradication of misinformation is an incomplete solution for societal disagreements.

Humans are remarkably adept at abstract rule learning, but little is known about when learners apply this knowledge. We investigated a fundamental constraint in rule generalization: attention to featural similarity (object bias). Across two experiments in different domains, we asked whether adults’ abstract rule generalization is constrained by superficial matches to the concrete exemplars present during learning, as is known to be the case for analogical reasoning (Gentner & Toupin, 1986). In the present studies, participants were exposed to a series of sequences following a simple rule and were asked to generalize to novel instances of either the same rule or a new rule. In one condition, an individual element present during initial learning was inserted into the new, unfamiliar pattern. Results showed that adults often chose this object match over the rule match, suggesting that abstract rule generalization, like analogical reasoning, is impacted by concrete features of the input.

How do children decide when to fact-check a claim? In two studies and a simulation, we show that children use environmental cues about informational reliability to rationally adapt their information seeking to enable the efficient detection of misinformation. In Study 1, children exposed to an environment containing some misinformation (as opposed to all true information) sampled more evidence before verifying a test claim in a novel domain. In Study 2, children showed a graded sensitivity to environmental reliability: information seeking increased linearly with the proportion of false statements heard during exposure. Additionally, these statements were presented as online search results, which demonstrated that children make sophisticated inferences about their informational environments, beyond speaker-specific cues, to adjust their skepticism toward new information. These results further emphasize the importance of considering the environmental context of learning when developing interventions to promote healthy skepticism and lifelong learning.

We rely heavily on information from the social world to inform our real-world beliefs. How is this social information used, and when is it most influential? We assess the role of one kind of social information, the prevalence of a belief, in belief updating. Using real-world pseudoscientific and conspiratorial claims, we show that increases in people’s estimates of the prevalence of a belief led to increases in their endorsement of said belief. Prevalence information elicited the strongest belief change when people were most uncertain of their initial belief, suggesting that people weigh social information rationally according to the strength of their initial evidence. We discuss the implications of our results in the context of the present misinformation epidemic.