2 claims in “developmental psychology, sociology”
Hart and Risley conducted intensive observational research on 42 families for one hour per month from when children were seven months old until age three, discovering differences in children were NOT due to physical care, race, gender, or financial resources, but rather to the quantity and quality of language interaction with parents.
By the end of age three, children from professional families had heard 30 million more words than children in poverty, with professional families speaking over 2,000 words per hour to their children compared to approximately 600 words per hour for families in poverty.