Not just a sum of its parts: How tasks of the theory of mind scale relate to executive function across time

There is a well-established relationship between theory of mind (ToM) and executive function (EF) during the preschool years. However, less is known about the concurrent and longitudinal relations between EF and specific tasks tapping different aspects of ToM. The current study investigated the ToM-EF relationship across 1 year in 3- to 5-year-old Turkish children using the ToM battery of Wellman and Liu (2004), which measures understanding of diverse desires (DD), diverse beliefs (DB), knowledge access (KA), contents false belief (CFB), explicit false belief (EFB), and hidden emotion (HE). This battery has not yet been used in its entirety to test the predictive relations between ToM and EF. We used peg-tapping and day-night tasks to measure EF. Our sample comprised 150 Turkish preschool children (69 girls) aged 36-60 months at Time 1 (T1) and 49-73 months at Time 2 (T2). Using the ToM composite with all six tasks, when child's age, receptive language, and T1 ability level (EF or ToM) were controlled, T1 EF significantly predicted T2 ToM, whereas T1 ToM did not predict T2 EF. Among DD, DB, KA, false belief understanding (FBU: the composite score of CFB and EFB), and HE, only KA and FBU were significantly associated with EF at T1 and T2. Further regression analyses showed that KA did not have a predictive relationship with EF. Instead, FBU drove the predictive EF-ToM relationship across time. Thus, in Turkish children, earlier EF predicts later ToM, but especially the FBU component, in this well-validated battery.