Young children, unlike adults, deny that improbable events can happen. We test two accounts explaining this developmental shift. The development = reflection account posits that this shift is driven by an emerging ability to reflect on modal intuitions. In contrast, the development = intuition account posits that this shift is driven by changes in modal intuitions themselves, due to age-related changes in what people know and how they sample their knowledge and memories. These accounts make competing predictions about how long children and adults should take to make possibility judgments. In Experiment 1, we asked 123 children (39 5-year-olds, 42 7-year-olds, 42 9-year-olds; 49.60% White) and 40 adults (50% White) to judge the possibility of 78 ordinary, improbable, and impossible events and recorded their response times. In Experiment 2, we tested an additional 52 adults (42.32% White) who were under speeded conditions and thus less able to reflect before responding. Our results favor the development = intuition account. At all ages, people judged improbable events more slowly than ordinary or impossible events, and slow responding did not consistently predict affirmation over denial. Further, adults' possibility judgments did not change under speeded conditions. We also fit a drift-diffusion model to our data, which suggested that adults and children may sample different kinds of knowledge when generating intuitions. Our findings suggest that possibility judgments are often driven by modal intuitions with little reflection, and that a developmental shift in what children know and how knowledge is retrieved can explain why these intuitions change over time.
Public Significance StatementJudging possibility is a core cognitive ability that interacts with many, if not all, domains of thought. We use our beliefs about what is possible to understand and infer what will happen in the distant future, what has happened in the past, what we are seeing right before our eyes, and all things in between. This work explored the development of how quickly these judgments are made, which allowed for a test of whether judgments about possibility become slower and more deliberative with age. Children are often framed as unsophisticated thinkers, employing frugal reasoning strategies which lead them to incorrect answers. Conversely, adults are thought to be more careful and deliberative in their thinking. This work suggests that children and adults use the same strategy to infer what is possible, and further suggests that this strategy is fast and frugal at all ages. The findings suggest that people's beliefs about what can happen are typically driven by quick intuitions rather than reflective reasoning, and that these intuitions are shaped by knowledge and memory retrieval patterns that change with age. This research highlights the importance of studying whether cognitive development can often be explained by changes in knowledge, as opposed to a developmental shift in reasoning strategies. Further, this work suggests that people...