Development and validation of the NIH Baby Toolbox® language measures

Abstract

Language acquisition is a fundamental aspect of infancy and early childhood development. This paper describes the development and validation of the language measures within the NIH Baby Toolbox® (Baby Toolbox), a state-of-the-art assessment system designed for children aged 16 days to 42 months. The Baby Toolbox language domain includes six measures that assess both expressive and receptive language—Looking while Listening, Picture Vocabulary, CDI-CAT Comprehension, CDI-CAT Production, Mullen Receptive, and Mullen Expressive. These measures, offered in both English and Spanish, leverage advanced technologies—such as computerized adaptive testing and gaze-based paradigms—to enhance both the accuracy and accessibility of the assessment. A large-scale norming study (N = 2490 children; 2025 English-exposed, 465 Spanish-exposed) provided strong evidence of reliability and validity, with high test-retest correlations and robust construct validity, although small sample sizes prohibited analyses for some of the Spanish measures. Findings support the Baby Toolbox as a reliable, scalable tool for assessing early language development in diverse populations.