biostudies-literatureUnknown96(5)Heise MJThis study describes a novel measure of children's Theory of Mind (ToM) development-called the Comprehensive Assessment of ToM (CAT)-that addresses limitations in existing ToM measures. This behavioral measure includes three-six items each about diverse desires, diverse beliefs, knowledge access, knowledge expertise, false belief, and visual perspective taking, as well as nonsocial representational reasoning (i.e., false-sign). All items include a prediction, explanation, and general comprehension question. The measure is psychometrically valid and robust in 3- to 8-year-old children (n = 206; 104 boys; 101 girls; 1 gender fluid; 37.7% White non-Hispanic). Children's performance replicates prior findings with the commonly used Wellman and Liu (2004) ToM scale, but also reveals a novel and nuanced pattern of mental-state scaling over early to middle childhood.Child development1787-1806https://www.ebi.ac.uk/biostudies/studies/S-EPMC12379850biostudies-literatureThe Comprehensive Assessment of Theory of Mind (CAT): A Novel Measure of 3- to 8-Year-Old Children's Theory of Mind and an Evaluation of Mental-State Scaling.PMC12379850Bowman LCHeise MJfalseThe Comprehensive Assessment of Theory of Mind (CAT): A Novel Measure of 3- to 8-Year-Old Children's Theory of Mind and an Evaluation of Mental-State Scaling.This study describes a novel measure of children's Theory of Mind (ToM) development-called the Comprehensive Assessment of ToM (CAT)-that addresses limitations in existing ToM measures. This behavioral measure includes three-six items each about diverse desires, diverse beliefs, knowledge access, knowledge expertise, false belief, and visual perspective taking, as well as nonsocial representational reasoning (i.e., false-sign). All items include a prediction, explanation, and general comprehension question. The measure is psychometrically valid and robust in 3- to 8-year-old children (n = 206; 104 boys; 101 girls; 1 gender fluid; 37.7% White non-Hispanic). Children's performance replicates prior findings with the commonly used Wellman and Liu (2004) ToM scale, but also reveals a novel and nuanced pattern of mental-state scaling over early to middle childhood.2025-01-01T00:00:00Z2025 Sep-Oct2026-05-10T04:26:07.505Z2026-04-08T01:29:10.326ZS-EPMC123798504065051610.1111/cdev.14263