Children's Understanding of How Past Experience Shapes Future Expectations.

As adults, we do not expect ignorant agents to behave randomly or always get things wrong. Instead, we expect them to act reasonably, guided by past experiences. We test whether 4-to-6-year-olds share this intuition and use it to infer others' knowledge, or whether they rely on a simple "ignorance = error" heuristic identified in past work.

People can infer the magnitude of other people's knowledge even when they cannot infer its contents.

Inferences about other people's knowledge and beliefs are central to social interaction. However, people's behavior is often consistent with a range of potential epistemic states, making it impossible to tell what exactly they know. Nonetheless, we are still often able to form coarse intuitions about how much someone knows, despite being unable to pinpoint the exact contents of their knowledge.

Six-Year-Olds, but Not Younger Children, Consider the Probability of Being Right by Chance When Inferring Others' Knowledge.

When determining what others know, we intuitively consider not only whether they succeed but also their probability of success in the absence of knowledge (e.g., random guessing).

When Naïve Pedagogy Breaks Down: Adults Rationally Decide How to Teach, but Misrepresent Learners' Beliefs.

From early in childhood, humans exhibit sophisticated intuitions about how to share knowledge efficiently in simple controlled studies. Yet, untrained adults often fail to teach effectively in real-world situations. Here, we explored what causes adults to struggle in informal pedagogical exchanges.

Preschoolers decide who is knowledgeable, who to inform, and who to trust via a causal understanding of how knowledge relates to action.

Preschoolers are discerning learners, preferring to trust people who are accurate, reliable, and appropriately-informed. Do these preferences reflect mental-state reasoning, where children infer what others know from their behavior, or do they reflect a reliance on simple cues? In Experiment 1 we show that four- and five-year-olds can infer knowledge from others' behavior when superficial cues and actions are matched across agents. Experiments 2a and 2b further suggest that children track how agents acquired their knowledge, and may use this to determine what different agents will (and will not) know.

People infer communicative action through an expectation for efficient communication.

Humans often communicate using body movements like winks, waves, and nods. However, it is unclear how we identify when someone's physical actions are communicative. Given people's propensity to interpret each other's behavior as aimed to produce changes in the world, we hypothesize that people expect communicative actions to efficiently reveal that they lack an external goal.

Not just what you did, but how: Children see distributors that count as more fair than distributors who don't.

To distribute resources in a fair way, identifying an appropriate outcome is not enough: We must also find a way to produce it. To solve this problem, young children spontaneously use number words and counting in fairness tasks. We hypothesized that children are also sensitive to other people's use of counting, as it reveals that the distributor was motivated to produce the outcome they believed was fair.

Says who? Children consider informants' sources when deciding whom to believe.

To successfully navigate the world, we cannot simply accept everything we hear as true. We must think critically about others' testimony, believing only sources who are well-informed and trustworthy. This ability is especially crucial in early childhood, a time when we both learn the most, and have the least prior knowledge we can fall back upon to verify others' claims.

In Pursuit of Knowledge: Preschoolers Expect Agents to Weigh Information Gain and Information Cost When Deciding Whether to Explore.

When deciding whether to explore, agents must consider both their need for information and its cost. Do children recognize that exploration reflects a trade-off between action costs and expected information gain, inferring epistemic states accordingly? In two experiments, 4- and 5-year-olds (N = 144; of diverse race and ethnicity) judge that an agent who refuses to obtain low-cost information must have already known it, and an agent who incurs a greater cost to gain information must have a greater epistemic desire. Two control studies suggest that these findings cannot be explained by low-level associations between competence and knowledge.

The Illusion of Consensus: A Failure to Distinguish Between True and False Consensus.

When evaluating information, we cannot always rely on what has been presented as truth: Different sources might disagree with each other, and sometimes there may be no underlying truth. Accordingly, we must use other cues to evaluate information-perhaps the most salient of which is consensus. But what counts as consensus? Do we attend only to surface-level indications of consensus, or do we also probe deeper and consider why sources agree? Four experiments demonstrated that individuals evaluate consensus only superficially: Participants were equally confident in conclusions drawn from a true consensus (derived from independent primary sources) and a false consensus (derived from only one primary source).

Changes in cognitive flexibility and hypothesis search across human life history from childhood to adolescence to adulthood.

How was the evolution of our unique biological life history related to distinctive human developments in cognition and culture? We suggest that the extended human childhood and adolescence allows a balance between exploration and exploitation, between wider and narrower hypothesis search, and between innovation and imitation in cultural learning. In particular, different developmental periods may be associated with different learning strategies. This relation between biology and culture was probably coevolutionary and bidirectional: life-history changes allowed changes in learning, which in turn both allowed and rewarded extended life histories.