The development of possibility judgment within and across domains

The ability to differentiate possible events from impossible ones is an invaluable skill when reasoning about claims that transcend the perceptual evidence at hand, yet preschool-aged children do not readily make this differentiation when reasoning about physically extraordinary events [Shtulman, A., & Carey, S. (2007). Improbable or impossible? How children reason about the possibility of extraordinary claims. Child Development, 78, 1015–1032]. The present study sought to determine whether this failure stems from deficits in domain-specific knowledge or deficits in the domain-general procedure by which possibility judgments are made. Participants (48 children aged 4-9 years olds and 16 adults) were asked to judge the possibility of three types of extraordinary events – physical, psychological, and biological – and to justify their judgments of impossibility. Developmental changes in the ability to differentiate improbable events from impossible events were qualitatively similar across domains. Moreover, participants’ propensity to judge improbable events possible was significantly correlated with the quality of their justifications, both within and across domains. These findings suggest that modal development involves a domain-general change in how modal claims are evaluated.