Young children and adults integrate past expectations and current outcomes to reason about others' emotions

Reasoning about others’ emotions is a crucial component in social cognition. Here, we tested the ability of preschool children to reason about an agent’s emotions following an unexpected outcome. Importantly, we controlled for the actual payoff of the outcome, while varying the prior expectation of the agents. Five-year-olds, but not four-year-olds, were able to correctly judge an agent’s emotions following an unexpected outcome (Experiment 1). When explicitly provided with the agent’s expectations, 4-year-olds were then also able to correctly judge the agent’s feelings (Experiment 2). Our results suggest that the ability to reason about emotions given outcomes and prior expectations develops by 4 years of age, while the ability to spontaneously infer such prior expectations develops soon after. We discuss our results in light of the developmental literature on emotion understanding and counterfactual reasoning.