Attention was first drawn to the importance of language nutrition two decades ago. Psychologists Betty Hart and Todd Risley at the University of Kansas tracked 42 families with young children for several years, noting the number and type of words that parents spoke to their children over the course of a typical day. The data revealed an alarming trend: by the age of 3, children from affluent families had heard some 30 million more words than their impoverished counterparts.

Early language exposure has since been linked to a number of cognitive skills, including attention, memory and emotional development. For example, studies of bilingual children – who hear a greater variety of sounds – suggest that they are better at tasks such as ignoring irrelevant information and switching between different activities. Those who hear more words early on also have larger vocabularies and better real-time word processing by the age of 2.

Such findings have persuaded policy-makers that more and better conversations can help kids from disadvantaged backgrounds get ahead in school and in life.