International Journal of Behavioral Development, Ahead of Print.
First-order theory of mind (ToM) development has shown to conform to a Guttman scale, with desire reasoning developing before belief reasoning. There have been attempts to test for internal consistency and scalability in advanced ToM, but not over a broad age range and only with a limited set of tasks. This 2-year longitudinal study (N = 155; Mage = 4.2; SD = 0.85 months; 68 girls, 87 boys) tests for the scalability of a broader range of ToM tasks, and we model the developmental transition from first-order to advanced ToM in 4- to 6-year-olds. Rasch analyses showed that psychometrically sound and developmentally sequenced scales emerge when measures of morally relevant and second-order false belief, as well as mental verb understanding, metacognition, and recognition of nonliteral speech are included. Individual differences were moderately stable over time, and there were systematic transitions from failure to success in children’s performance, suggesting that conceptual continuity exists between first-order and advanced ToM.