What do babies need in order to learn and thrive? One thing they need is conversation — responsive, back-and-forth communication with their parents and caregivers. This interactive engagement is like food for their developing brains, nurturing language acquisition, early literacy, school readiness, and social and emotional well-being. A dispiriting number of children don’t get that kind of brain-fueling communication, research suggests. In early childhood policy (and in the wider media), much attention has been paid to the so-called word gap — findings that show that low-income children hear 30 million fewer words, on average, and have less than half the vocabulary of upper-income peers by age three. But putting that alarming number in the spotlight obscures a more critical component of the research, says Harvard Graduate School of Education literacy expert Meredith Rowe: it’s not so much the quantity of words but the quality of the talk that matters most to a child’s development.