Does expressive vocabulary size at 24 months of age predict language ability at 15 years of age?

Late talking is a known risk factor for persistent language learning difficulties. However, at individual level the predictive value of late talking is low, as up to 80% (depending on the criteria used) of late talking children will later have language abilities within age expectations. In this study, a sub-study to the STEPS Study, we studied long-term predictive value of early vocabulary development as a continuum from weak to strong (N = 195) In addition to this, we were especially interested in whether a larger than usual expressive vocabulary would be a more reliable predictor for later language abilities than late talking, suggesting that modest predictive value of late talking would at least partly be due to early vocabulary being suboptimal measure in terms of validity or reliability. We might assume that children with a large vocabulary must have strong language abilities whereas within children with small expressive vocabularies the reason for late talking may also be other than linguistic, e.g. temperament. The 15-year data collection ended in January 2025 and the results analyzed during spring 2025 will be discussed in the presentation.

Grossheinrich, N., Schulte‐Körne, G., Marschik, P. B., Kademann, S., von Suchodoletz, W., & Sachse, S. (2019). School‐age outcomes of late‐talking toddlers: Long‐term effects of an early lexical deficit. Developmental Science, 22(6). https://doi.org/10.1111/desc.12826

Lagstrom, H., Rautava, P., Kaljonen, A., Raiha, H., Pihlaja, P., Korpilahti, P., Peltola, V., Rautakoski, P., Osterbacka, E., Simell, O., & Niemi, P. (2013). Cohort Profile: Steps to the Healthy Development and Well-being of Children (the STEPS Study). International Journal of Epidemiology, 42(5), 1273–1284. https://doi.org/10.1093/ije/dys150

Matte-Landry, A., Boivin, M., Tanguay-Garneau, L., Mimeau, C., Brendgen, M., Vitaro, F., Tremblay, R. E., & Dionne, G. (2020). Children with persistent versus transient early language delay: Language, academic, and psychosocial outcomes in elementary school. Journal of Speech, Language, and Hearing Research, 63(11), 3760–3774.