Exploring Sentence Diversity at the Boundary of Typical and Impaired Language Abilities.
Pamela A Hadley
PMID 33064603WHAT IT FOUND
Toddlers with severe language delays often lack third-person subjects at 30 months, even when producing diverse 'I' sentences.
This specific gap predicts persistent impairment. Clinicians should monitor third-person subject diversity as an early risk marker, not just total sentence length.
Key findings
01Absence of third-person subjects at 30 months raises clinical concern and warrants monitoring through 36 months.
02Children with severe grammatical delays showed limited or absent third-person subjects at 36 months, despite producing diverse sentences with first-person 'I' subjects.
03Third-person subjects emerged more readily in one-argument copula contexts and with intransitive verbs than in two-argument transitive sentences.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study is descriptive and observational; it identifies a marker of risk but does not prove that targeting these structures improves outcomes. Participants were primarily from White, non-Hispanic, college-educated homes, so the developmental expectations may not generalize to culturally or linguistically diverse populations. The sample size for the severe delay group was small (n=7), limiting the precision of the prevalence estimates for late-emerging third-person subjects. The analysis focused on active declarative sentences, potentially missing diversity in questions or imperatives.
Declared interests
The research was supported by the National Institutes of Health (N.I.H., Extramural). The authors declared no other conflicts of interest.
The easy way to misread this
Do not interpret the lack of third-person subjects as a general inability to combine words or a cognitive deficit. The study shows that children with severe delays can produce complex 'I' sentences; the specific gap is in representing the third-person subject, which requires distinct grammatical knowledge.