The quality of child-directed speech depends on the speaker's language proficiency.
Erika Hoff, Cynthia Core, Katherine F Shanks
PMID 31296271WHAT IT FOUND
In English toy play, mothers with limited self-rated proficiency used fewer different words, shorter utterances, and less varied verbs than native or proficient non-native speakers.
The study did not measure child language outcomes.
Key findings
01Mothers' proficiency group was a significant source of variation in every measure of child-directed speech quality tested.
02Native speakers showed the most supportive properties, non-native speakers with good proficiency showed intermediate levels, and non-native speakers with limited proficiency showed the lowest levels.
03Proficiency group did not significantly affect quantity measures: total word tokens, rare word tokens, or lexical nouns used as sentence subjects.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study measured mothers' speech, not children's language outcomes, so it cannot show that proficiency differences caused poorer child language growth. Proficiency was based on coarse self-report categories, and the limited-proficiency group was small. It analyzed only English toy-play in a lab, not Spanish speech, book-reading, or everyday language environments. Mothers were not randomly assigned to proficiency groups, so differences could reflect acculturation or other family factors. The findings apply to properties of input, not to every aspect of mother-child interaction or bilingual development.
Declared interests
The article is listed as supported by N.I.H. Extramural research funding; the supplied text does not give a separate conflict-of-interest declaration.
The easy way to misread this
Do not conclude that children of non-native speakers will have language delay or that helping parents improve English proficiency will improve child language. This study measured mothers' speech properties, not child outcomes, and it was observational.