lower socioeconomic status predicts a less stimulating environment for a child—all those enriching extracurricular activities that can’t be afforded, the world of single mothers working multiple jobs who are too exhausted to read to their child. As one shocking manifestation of this, by age three, your average high-socioeconomic status kid has heard about thirty million more words at home than a poor kid, and in one study, the relationship between socioeconomic status and the activity of a child’s PFC was partially mediated by the complexity of language use at home.[47]
