How children and adults keep track of real information when thinking counterfactually.

Thinking about counterfactual conditionals such as "if she had not painted the sheet of paper, it would have been blank" requires us to consider what is conjectured (She did not paint and the sheet was blank) and what actually happened (She painted and the sheet was not blank). In two experiments with adults (Study 1) and schoolchildren from 7 to 13 years (Study 2), we tested three potential sources of difficulty with counterfactuals: inferring, distinguishing what is real vs conjectured (epistemic status) and comprehending linguistic conditional expressions ("if" vs "even if"). The results showed that neither adults nor schoolchildren had difficulty in the comprehension of counterfactual expressions such as "even if" with respect to "if then". The ability to infer with both of these develops during school years, with adults showing great ability. However, the third source factor is critical: we found that the key to young children's difficulty with counterfactual thinking was their inability to differentiate real and conjectured information, while adults showed little difficulty with this.