You can't change the past: Children’s recognition of the causal asymmetry between past and future events
Children’s temporal and causal reasoning skills improve substantially during early childhood, but it remains unclear when they fully understand the conceptual distinction between the past and the future. Here we explored U.S. 3- to 6-year-old children’s (n = 228) and adults’ (n = 60) understanding that acting in the present can change the future but not the past. To do so, we told participants 3-step causal stories, e.g., “(1) When Sally flips the light switch, (2) the light turns on, (3) so she can see to find her toy,” and asked about the effects of an action at event 2, e.g., “What if John turned off the light?”. When asked about the effects of the change on the future consequent event (3), only 3-year-olds responded at chance, while 4- to 6-year-olds became increasingly likely to judge that the future event would also change. However, when asked about the effects of the change on the past antecedent event (1), children of all ages, like adults, consistently judged that the past event still occurred. This suggests that children have an early-developing understanding that the past cannot be changed. Using a similar paradigm, we also explored children’s reasoning about the implications of the non-occurrence of event 2, in which the cause was not specified, e.g., “What if the light didn’t turn on?”. Both children and adults reasoned differently about these scenarios than they did about those involving actions by external agents. In particular, adults and 6-year-olds inferred that the antecedent event also had not occurred. Implications for theoretical accounts of causal and temporal reasoning are discussed.