The ability to imagine alternative possibilities plays a crucialrole in everyday cognitive functioning beginning in earlychildhood. Across two studies, we ask whether individualdifferences in young children’s (Mean Age = 5.01; SD = 0.78Range = 2) fluency in generating alternative possibilitiesrelates to a particular type of social-cognitive counterfactualjudgment, namely children’s belief in the possibility to “actotherwise” when actions go against stated strong desires (i.e.“free will”). We found that the fluency of generating ideaswas a consistent individual difference that held regardless ofdomain. We also found that individual children’s fluencypredicted judgments of free will for themselves (Study 2) butnot for others (Study 1). Our findings raise new questionsabout how counterfactual thinking enables children toovercome psychological barriers to self-control, and howstimulating the imagination facilitates developing cognitionsthat rely on it.

Investigating folk conceptions of choice and constraints havebeen problematic given that human actions are rarelyconsidered constrained. In this paper, we utilize humanoidrobots (more clearly influenced by determined programming)to empirically test children’s developing concepts of choiceand action. Using a series of agency attribution and choiceprediction tasks, we examined whether children differentiatefree will abilities between robots and humans. Resultsindicated that 5–7-year-old children similarly attributed theability to choose to both a robot and human child. However,for moral scenarios, participants considered the robot’s actionsto be more constrained than the human. These findingsdemonstrate that children appear to hold a nuancedunderstanding of choice across agents and across context.

Children exhibit sophisticated explanatory judgments: they expect, value, and judge explanations of salient facts. Do children also believe that everything must have an explanation? If so, they would exhibit a metaphysical explanatory judgment conforming to what philosophers have called the Principle of Sufficient Reason (PSR). In this study, 6-9-year-old children (N = 80, Mage = 7.92, SDage = 1.21) were shown statements across domains (Psychology, Biology, Nature, Physics, Religion, and Supernatural) and asked if they agree that each statement must have an explanation. As a foil, children were also asked about coincidences, which, putatively, aren’t apt for explanation. Indeed, children conform to the PSR: children of all ages believed that the statements must have an explanation. Notably, 7-9-year-olds thought coincidences don’t have to have an explanation, while 6-year-olds didn’t differ between the statements and coincidences. This is the first step at uncovering a developmental change in our metaphysical explanatory judgments.

Psychological scientists have become increasingly concerned with issues related to methodology and replicability, and infancy researchers in particular face specific challenges related to replicability: For example, high-powered studies are difficult to conduct, testing conditions vary across labs, and different labs have access to different infant populations. Addressing these concerns, we report on a large-scale, multisite study aimed at (a) assessing the overall replicability of a single theoretically important phenomenon and (b) examining methodological, cultural, and developmental moderators. We focus on infants’ preference for infant-directed speech (IDS) over adult-directed speech (ADS). Stimuli of mothers speaking to their infants and to an adult in North American English were created using seminaturalistic laboratory-based audio recordings. Infants’ relative preference for IDS and ADS was assessed across 67 laboratories in North America, Europe, Australia, and Asia using the three common methods for measuring infants’ discrimination (head-turn preference, central fixation, and eye tracking). The overall meta-analytic effect size (Cohen’s d) was 0.35, 95% confidence interval = [0.29, 0.42], which was reliably above zero but smaller than the meta-analytic mean computed from previous literature (0.67). The IDS preference was significantly stronger in older children, in those children for whom the stimuli matched their native language and dialect, and in data from labs using the head-turn preference procedure. Together, these findings replicate the IDS preference but suggest that its magnitude is modulated by development, native-language experience, and testing procedure.