Human Growth and Development / Unit 5 HGD 0622 short lesson, about 20 seconds
The Thirty-Million-Word Gap
Captions available
The idea
Hart and Risley reported that children in higher-income homes heard about thirty million more words by four, and vocabulary tracked that exposure.
In practice
One family's hours of recorded talk, counted word by word over two years.
Where people slip
Later work questions the method and figure; language exposure and child-directed speech, not income itself, best predict later language.
Your place on the trail
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