Third person singular -s in typical development and specific language impairment: Input and neighbourhood density.
Justin B Kueser, Laurence B Leonard, Patricia Deevy
PMID 28727489WHAT IT FOUND
Children with SLI used third person singular -s less often than peers, but verbs that appeared more often with -s in child-directed speech were more likely to be inflected in both groups.
For children with SLI, sparse verbs were associated with more inflection.
Key findings
01Children with SLI used third person singular -s on 43% of opportunities, compared with 63% for typically developing children.
02A verb appearing with third person singular -s in 20% of input had 2.46 times greater odds of being inflected than a verb appearing with it 0% of the time, across both groups.
03Children with SLI were more likely to inflect sparse verbs than dense verbs, while typically developing children did not show this density difference.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The analysis used children who showed inconsistent third person singular -s use, so it does not describe children who were already consistent. Input proportion came from a general parent-child speech corpus, not from each child's own parents or caregivers. The study observed associations in probe productions. It did not test whether changing input or verb choice causes better use of third person singular -s. Children with SLI had been receiving language intervention at the time of the original data collection. The neighbourhood density measure did not include the frequency of each neighbouring word. All children spoke Standard American English, and the input measure came from an American English corpus. The findings may not apply to other dialects or languages.
Declared interests
The authors report no conflicts of interest. The article is tagged as supported by NIH extramural research funding.
The easy way to misread this
Do not conclude that using sparse verbs or verbs that appear often with -s in child-directed speech will improve a child's third person singular -s use. This study measured associations in children's productions, not treatment outcomes, and input came from a general corpus rather than each child's own speech.