Sentence-focused diversity measures (Hadley et al., 2025)
Purpose: The purpose of this study was to evaluate the construct validity of three sentence-focused diversity measures, intransitive verb diversity, transitive verb diversity, and third person (3P) subject diversity, using two methods: (a) group differentiation of late-talking (LT) toddlers from peers with typically developing (TD) language and (b) associations with established measures of language development. A secondary purpose was to determine whether 3P subject diversity was more strongly associated with intransitive verbs than transitive verbs.
Method: Examiner–child language samples from 58 LT toddlers and 82 TD toddlers (ages 24–30 months) were collected using a structured language sampling protocol. Transcripts were coded to obtain measures of intransitive verb diversity, transitive verb diversity, and 3P subject diversity as well as mean length of utterance (MLU) and number of different words (NDW). We used nonparametric tests to examine differences between groups and associations between measures within each group. We also conducted an exploratory analysis using a generalized linear mixed model to determine the strength of associations for intransitive and transitive verb diversity with 3P subject diversity.
Results: All sentence-focused diversity measures were significantly different between groups. They were also positively related to MLU, NDW, and to each other within each group. Both intransitive verb diversity and transitive verb diversity were significantly associated with 3P subject diversity, after accounting for NDW; however, the strength of association observed between intransitive verb diversity and 3P subject diversity was nearly twice as large.
Conclusions: These findings provide new evidence that sentence-focused diversity measures are valid indicators of early language development and that intransitive verbs have a stronger association with diverse 3P subjects than transitive verbs. The value of adopting measures of verb and subject diversity with LT toddlers is discussed.
Supplemental Material S1. Independent-samples Mann-Whitney U test status: Age.
Supplemental Material S2. Independent-samples Mann-Whitney U test status: MLU in morphemes.
Supplemental Material S3. Independent-samples Mann-Whitney U test status: Number of different words.
Supplemental Material S4. Independent-samples Mann-Whitney U test status: Transitive verb diversity.
Supplemental Material S5. Independent-samples Mann-Whitney U test status: Intransitive verb diversity.
Supplemental Material S6. Independent-samples Mann-Whitney U test status: Subject diversity.
Supplemental Material S7. Demographics for in study sample relative to out of study sample from W2W cohort.
Supplemental Material S8. Model building outputs for generalized linear mixed effect models.
Hadley, P. A., Harrington, E. K., Krok, W. C., Preza, T., Harriott, E. M., Manning, B. L., Wakschlag, L. S., & Norton, E. S. (2025). Evaluating the construct validity of sentence-focused diversity measures with late-talking toddlers and same-age peers. Journal of Speech, Language, and Hearing Research, 68(4), 1886–1901. https://doi.org/10.1044/2024_JSLHR-24-00558
Funding
This work was supported by the National Institute on Deafness and Other Communication Disorders Grant R01DC016273 (awarded to Elizabeth Norton and Lauren Wakschlag [MPIs]), as well as support from the National Institute of Mental Health Grant R01MH107652 (awarded to Lauren Wakschlag). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
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