Literacy predicts performance on a second-order false-belief task.

The vast majority of research on false-belief understanding has been conducted with literate populations. However, to our knowledge, no prior study has examined how literacy acquisition itself influences false-belief reasoning. The development of false-belief understanding is shaped by a range of factors, including language skills, education, reading experience, and cognitive abilities. Illiterate speakers often show substantial variability in language skills and cognitive abilities. In this study, we investigated the impact of nonverbal IQ, inhibitory control, and reading fluency on false-belief understanding in adult native Turkish speakers, comparing literate and illiterate participants. We found considerable individual differences in false-belief performance across both groups, as well as in the cognitive measures. Strikingly, reading fluency (assessed via a 1-minute timed word-reading task) emerged as the most significant predictor of false-belief performance, accounting for 49% of the variance. We propose that literacy acquisition may support the development of false-belief reasoning by enhancing language skills, cognitive control, metalinguistic awareness, and perspective-taking through engagement with written narratives. These findings carry broader implications for psychology, linguistics, and adult education.