French Williams syndrome's ability to produce judgments of grammaticality.
Adults with Williams syndrome judge grammar like seven-year-olds—plan for a lifelong plateau, not a delay.
01Research in Context
What this study did
Lallier et al. (2014) asked French-speaking adults with Williams syndrome to judge if spoken sentences were correct or wrong.
They compared the adults to seven-year-old children who spoke the same language.
The team wanted to see if grammar sense in Williams syndrome keeps growing with age or mental age.
What they found
The adults with Williams syndrome scored like the seven-year-old kids.
Neither higher chronological age nor higher mental age helped the adults do better.
The skill looked frozen at the seven-year-old level.
How this fits with other research
Lacroix et al. (2010) saw the same freeze in idiom understanding, so the plateau is not limited to grammar.
Boloh et al. (2009) found a similar stall in gender agreement, showing the pattern holds across French grammar rules.
Libero et al. (2016) tracked younger children with Williams syndrome over time and confirmed that receptive syntax stays flat while vocabulary keeps climbing.
Together these studies build a clear picture: in Williams syndrome, expressive words can grow, but core grammar sense hits a ceiling early and stays there.
Why it matters
If you assess an older client with Williams syndrome, do not trust strong eye contact and rich vocabulary. Probe grammaticality with simple judgment tasks. Set language goals around vocabulary, pragmatics, and scripts, not advanced syntax. Expect the same error pattern at age 25 as at age 7 and plan supports that sidestep complex grammar.
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02At a glance
03Original abstract
This article reports grammatical judgment data from eighteen French Williams syndrome (WS) (mean CA = 21.10; Mean MA = 11.2). Participants had to detect ungrammatical sentences (13 amongst a set of 26 sentences) in telling whether a given sentence was well said or not. Agrammaticality could be due to errors in tense, person agreement, gender agreement, derivational or inflectional morphology, word order and so on. As a group, WS participants scored as seven-year-olds did, far below CA-controls and MA-controls. Scores did not improve with chronological age or mental age but they were related to total IQ and verbal IQ. They showed an important variability, one similar to what was observed in four-year-olds. Although a few WS individuals had good metasyntactic abilities, these abilities generally plateau in our WS group. They were not deviant, however, as the WS's profile of difficulties across items was qualitatively very similar to the one seen in seven-year-olds.
Research in developmental disabilities, 2014 · doi:10.1016/j.ridd.2014.08.010