Counterfactual reasoning is at the centre of human daily life and plays a key role in shaping our moral and social judgments. Its effect on moral judgment in adulthood, such as justifying immoral behavior (e.g., “If you had not left your phone on the table, it would not have been stolen.”), has been studied for years. However, we still know very little about when counterfactual reasoning starts to affect humans' moral judgments. To test this, we examined the effect of better and worse counterfactual alternatives on 5-6-year-olds' (N = 91) moral and happiness judgments. We found that children judged social exclusion (e.g., a new kid has to play alone while other children play together) as less morally acceptable after imagining how it could have been better (e.g., the new kid and other children at the school could have played all together), but, contrary to past work with adults, they did not justify it after imagining how it could have been even worse (e.g., the other children could have broken the new kid's toy). However, children's happiness judgments showed the opposite effect: they reported feeling happier about reality after imagining a worse counterfactual alternative compared to children who only thought about what actually happened. Keywords: counterfactuals; moral judgment; children; happiness judgment

As adults, we readily work through alternative possibilities and their potential consequences in our minds before acting. This capacity for mental simulation enables us to internally explore alternatives without incurring costs of acting in reality. Young children are highly exploratory in the real world, but little is known about their ability to engage in internal exploration via mental simulation. This preregistered study (1) examines developmental changes in the use of mental simulation when solving problems with multiple options, and (2) investigates the influence of resource availability on the tendency to simulate. Adults (N=30) and 4-to 7-year-olds (target N=120; data collection ongoing) completed computer-based puzzles where they chose where to drop balls into a vertical maze to hit a goal. Accuracy and latency to act were measured as indices of mental simulation. Our findings will contribute to understanding children's problem-solving, and could lead to a new conceptualization of their exploratory behaviour.

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.

Children often fail to control variables when conducting testsof hypotheses, yielding confounded evidence. We propose thatgetting children to think of alternative possibilities throughcounterfactual prompts may scaffold their ability to controlvariables, by engaging them in an imagined intervention that isstructurally similar to controlled actions in scientificexperiments. Findings provide preliminary support for thishypothesis. Seven- to 10-year-olds who were prompted to thinkcounterfactually showed better performance on post-testcontrol of variables tasks than children who were given controlprompts. These results inform debates about the contributionof counterfactual reasoning to scientific reasoning, and suggestthat counterfactual prompts may be useful in science learningcontexts.

Children struggle to conduct controlled tests, even with explicit instruction (Chen & Klahr, 1999). How learners approachmultivariable tasks can be affected by task goals; a scientist uncovers causal regularities whereas an engineer produceseffects (Klahr, et al., 2011). This study investigated whether science vs. engineering goals presented in a narrative picturebook influenced childrens ability to conduct a controlled test.Six-to-8-year-olds (N=72) were first pre-tested on their ability to design a controlled test of a variable predicting how fara ball travels down to a ramp. Children were then read a picture book that contained a science (conduct controlled test) orengineering (create faster ramp) goal. Next, they completed an identical post-test and transfer-test with two new variables.Childrens ability to design a controlled test improved significantly from pre- to post-test (p=.008) and marginally frompre-test to transfer (p=.067) in both conditions, suggesting that children learned from both goals.