Play and curiosity are unmistakable signatures of an active mind. It is perhaps unsurprising then, that recent advances in machine learning and robotics have used algorithmic approximations of curiosity to build artificial agents that can intelligently explore their environments, learn more efficiently, and acquire more generalizable skills (e.g. Chitnis et al., 2020; Lynch et al., 2020; Forestier et al., 2017).

People are often reluctant to reconsider their choices, sticking with their goals even when it is clear that they would be better off abandoning them. Explanations for this abound, including loss aversion, sunk costs, social and reputational pressures, and resource rational consideration of the costs of replanning. Here we propose another hypothesis: In adopting a goal, you immediately reap the rewards of gaining information about what to do and how to act. Insofar as goals are rewarding in themselves, we predict that unless a goal is specifically devalued or the costs associated with it are very high, the default is not to engage in any reconsideration at all. We test this hypothesis by creating a stripped down scenario involving choices between two goals with transparently obvious cost differentials. The task is designed to minimize other factors that might contribute to goal persistence and indeed, we test both adults and very young children on virtually the same task to ensure that the cognitive load for adults is negligible. Both adults (Experiments 1-2) and 4-6-year-old children (Experiments 3-4) choose the less costly of two goals when shown the costs and goals together. However, when participants are shown the goals first, and only then shown that their chosen goal is more costly than the alternative, participants stick with higher cost goals, unless the goals are explicitly devalued.

Prior research has shown that children are highly responsive to adults' attention, benefit from its presence, and suffer in its absence. However, not much is known about the extent to which children track other's attention to third parties, or the extent to which children actively make decisions and plans to engage adults' attention. In Experiment 1, we looked at whether children (mean: 5;11 range: 4;0-7;11) distinguished attentive and distracted adults in a minimal contrast where attention to a third party (a puppet) was all that varied and the adults were otherwise matched on affect, contingent responding, and other cues. Six- and seven-year-olds but not younger children predicted that the puppets would prefer the attentive adults. In Experiment 2, we looked at whether children (mean: 5;11 range: 4;0-7;11) tracked the co-variation between an adult's attentiveness and a puppet's topics of conversation. We found that older, but not younger children chose the puppets' next topic according to what the co-variation data indicated would best engage the adults' attention. These results suggest that by ages six and seven, but not earlier, children track adults' attention even in third-party contexts and can plan interventions to engage adults' attention.

Speakers are often over-informative, referring to the color and shape of a referent even when all objects in a scene are unique. Interestingly, this helps listeners locate the target. If speakers are indeed sensitive to listeners' online processing demands, they should be more over-informative when addressing someone whose processing is especially slow. Here we show that English-speaking adults produce more redundant color adjectives when speaking to children than adults (Exp 1); that although Spanish-speakers produce fewer redundant color adjectives than English-speakers overall, they too do so more often for children (Exp 2); that these results are independent of experience with young children (Exp 3), and that children themselves (ages 4-10) are more over-informative when speaking to younger children than adults (Exps 4 and 5). Collectively, these results suggest that sensitivity to listeners' online processing demands is robust, emerges early in development, and may be especially tailored to young learners.

Abundant work has looked at children’s ability to appropri- ately reject testimonies and unverified claims (Butler et al, 2017; Frazier, Gelman, & Wellman, 2009; Koenig, Clement, & Harris, 2004). However, sometimes our current knowledge is insufficient for solving a problem. In these cases, we should reject unsatisfying facts and prefer satisfying, if speculative, conjectures. In two studies, we gave 4-7 year-old children (Study 1, N=66; Study 2, N=32) questions that either could or could not be answered with available information. For each question, children made a binary choice between a factual an- swer citing information from the story or a conjectural answer that made unverified claims. Across age groups, children suc- cessfully chose the more satisfying response regardless of its truth value: children chose facts for questions with known an- swers and conjectures for questions with unknown answers. These findings suggest that children will go beyond known in- formation to endorse unverified claims when they satisfy the question-under-discussion.

Play is a universal behavior widely held to be critical for learning and development. Recent studies suggest children’sexploratory play is consistent with formal accounts of learning. This ”play as rational exploration” view suggests thatchildren’s play is sensitive to costs, rewards, and expected information gain. By contrast, here we suggest that a definingfeature of human play is that children subvert normal utility functions in play, setting up problems where they incurneedless costs to achieve arbitrary rewards. Across three studies, we show that 4-5-year-old children not only infer playfulbehavior from observed violations of rational action (Experiment 1), but themselves take on unnecessary costs and performinefficient actions during play, despite acting efficiently in non-playful, instrumental contexts (Experiments 2-3). We endby discussing the value of apparently utility-violating behavior and why it might serve learning in the long run.