Children acquire conditionals late for reasons that are poorly understood. One possibility is because conditionals have multiple meanings. For instance, the statement “If he goes out without an umbrella, he will get wet” is logically true when he goes out without an umbrella and he gets wet (conjunction), when he goes out with an umbrella and does not get wet (bi-conditional) and when he goes out with an umbrella and (still) gets wet (conditional). Here, we employ a new paradigm to test these interpretations in young children. Eighty 3-6-year-olds were asked to match an if-then statement with one of two pictures: 1 depicting a scenario where the conditional is false vs. one of the 3 scenarios where the conditional is true. Results show that children had a conjunctive interpretation since age 3 but the development of the other two interpretations is protracted until after age 5, with great inter-subject variation.

Speakers often violate conversational expectations by offering less information than listeners need (Grice, 1975). Althoughchildren appear sensitive to such violations as comprehenders (Gweon & Asaba, 2018; Katsos & Bishop, 2011), it isunclear how they would respond to them in a reciprocal conversational setting. Here, we ask whether children tailor theinformativeness of their speech based on the informativeness of an interlocutor in a prior interaction. In an informativenessrating task, 4- and 5-year-old children evaluated the utterances of an informative and an under-informative interlocutor.Then, in a referential communication task, roles were reversed, and children produced referential descriptions for either theinformative or the under-informative interlocutor. Results showed that although children were sensitive to conversationalviolations, they did not tailor their utterances to their interlocutors informativeness. Although preliminary, these findingssuggest that cooperative expectations in linguistic exchanges might differ from those underlying broader (non-linguistic)social action.

Whether logical inference is available without language is highly debated. One such inference is the disjunctive syllogism(A Or B, Not A, Therefore B). Evidence from a search task that required disjunctive reasoning suggests that that thesyllogism is unavailable before age 3 (Mody & Carey, 2016). However, in a replication of the same task using language(i.e., verbal negation), even 2.5-year-olds succeeded (Grigoroglou, et al., 2019). Here we explore the role of languagein childrens logical reasoning. 2.5- to 4-year-olds performed the non-linguistic task, after a short training in reasoningby exclusion. Half of the children received linguistic training (e.g., heard there is no coin in X cup); half received non-linguistic training (i.e., saw that one location was empty). Results show that 2.5- and 3-year-olds were more successful inreasoning with the disjunctive syllogism after the linguistic training. Thus, offering children the premise Not A verballyfacilitated logical reasoning.

Conditionals have multiple interpretations: the statement "If it rains, Abbie will buy an umbrella" is true when it rains and Abbie buys an umbrella (conjunction), when it doesn’t rain and Abbie doesn’t buy an umbrella (biconditional), and when it doesn’t rain and Abbie buys an umbrella (conditional). Prior research shows that children understand all three interpretations in adolescence, but the reasons for this delay remain unclear. For some researchers, children struggle to represent multiple possibilities due to limited resources. For others, task-related factors underlie children’s difficulties. In a truth-value judgement task, 3-10-year-olds matched a conditional statement with one of two pictures: 1 depicting a false interpretation of the conditional vs. one of the 3 true interpretations. Results showed that children understood conjunction since age 3 but comprehended all three conditional interpretations at age 9, earlier than previously thought. Findings point to a task-related explanation of children’s difficulties.

Fiction presents a unique challenge to the developing child, in that children must learn when to generalize information from stories to the real world. This study examines how children acquire causal knowledge from storybooks, and whether children are sensitive to how closely the fictional world resembles reality. Preschoolers (N = 108) listened to stories in which a novel causal relation was embedded within realistic or fantastical contexts. Results indicate that by at least 3 years of age, children are sensitive to the underlying causal structure of the story: Children are more likely to generalize content if the fictional world is similar to reality. Additionally, children become better able at discriminating between realistic and fantastical story contexts between 3 and 5 years of age.

Across 3 studies, we investigated children's ability to consider hypothetical interventions to complex and dynamic causal systems. Five- to 7-year-olds learned about novel food chains and were asked about the effects of the removal of one species on others in the food chain. In Studies 1 (n = 72) and 2 (n = 72), 6- and 7-year-olds made correct inferences about the effects on remaining species, but performed better when reasoning about direct predators or prey than indirectly-connected species. Five-year-olds' performance was at chance across all question types. In Study 3 (n = 65, target n = 72), we are currently investigating whether 5-7-year-old children’s performance improves when given more background information on the causal dynamics of the food chains. The results indicate that hypothetical thinking about dynamic causal systems develops between 5 and 7 years. This ability may be leveraged for teaching science concepts.

This study examined whether embedding explanations in guided activities promotes conceptual change about a physicalscience concept. One common misconception that children have is that heavy objects fall at a faster rate than light ones.We used a pre-, post-, and delay test design to address this misconception. Forty 5-year-old children were assigned to oneof two conditions: a guided play activity that included an explanation about gravity, or the same guided play activity butwith no explanation provided. Childrens explanations improved immediately at post-test (p =.001, 95% CI [0.58, 2.33])and after a one-week delay test (p ¡.001, 95% CI [1.23, 2.95]) when the explanation about gravity was embedded in theactivity. There was no improvement at post-test (p =.36) or delay-test (p =.93) when children completed the activity only.This study shows that conceptually rich explanations are an effective pedagogical tool for promoting belief revision inchildren.

Whether logical inference is available without language is highly debated. One such inference is the disjunctive syllogism (A Or B, Not A, Therefore B). Evidence from non-linguistic search tasks suggests that that the syllogism may be unavailable before age 3 (Mody & Carey, 2016). However, in a replication of the same task using language (i.e., verbal negation), even 2.5-year-olds succeeded (Grigoroglou, et al., 2019). Here we explore the role of language in children's logical reasoning. 2.5-, 3- and 4-year-olds performed a non-linguistic search task, after a short training in reasoning by exclusion. Half of the children received linguistic training (e.g., heard “there is no coin in X cup”); half received non-linguistic training (i.e., saw that one location was empty). Results show that 2.5-year-olds who received linguistic training succeeded in disjunctive syllogism but those who received non-linguistic training failed. We conclude that the presence of verbal negation facilitated logical reasoning.