Infant shy temperament predicts preschoolers Theory of Mind

•We investigated the impact of infant temperament on early Theory of Mind.•Infant shyness predicted ToM abilities at 3 years of age.•The results are in line with a social-emotional reactivity perspective.•The relation between temperament and ToM is not unique to false-belief understanding.

The aim of this longitudinal study was to investigate the relation between infant temperament at 18 months and early Theory of Mind (ToM) abilities at 3 years of age. Temperament was assessed with the Early Childhood Behavior Questionnaire (ECBQ) and ToM by assessing children's understanding of divergent desires and beliefs, and of knowledge access. Our results are in line with a social-emotional reactivity perspective postulating more sophisticated ToM abilities for children with less reactive more observant temperament. Children with shy temperament at 18 months and at 3 years were better in reasoning about others’ mental states at age 3. Language, siblings and parental education had no effect on ToM. Findings indicate that temperament is related to ToM earlier in development than previously found, and that this relation is thus not unique to false-belief understanding.