The gaps we have discussed so far are strongly related to the types of early experiences children have at home and in caregiving settings. Greater income can be used to purchase goods and enriching opportunities like high-quality child care and early education, whereas a lack of resources may mean lower-quality or unstable care (although there is some evidence that children just above poverty or from middle-income families may receive the lowest-quality care; see Phillips et al., 2008). In addition to the positive experiences that money can buy, it reduces economic hardship that contributes to parent stress, which carries over to children. Indeed, there is evidence that parenting behaviors and parenting style are a driving force in the achievement gaps evident between lower and higher income children.
Children from lower income and/or lower SES families experience differences in parenting and home language, literacy, and cognitive environments. Such children often experience less rich verbal environments at home with family and in caregiver interactions over the first four years of life. As described in Hart and Risley's (1995) seminal study, by age 3, a child from a low-SES family (based on parental occupation) will be exposed to approximately 13 million words, on average, compared to 45 million words for a child from a high-SES family. Children from lower SES families also have less exposure to enriched learning environments, including access to and use of children's books and other materials, and experience more television time, relative to children from higher SES families.
Children's differential access to educational, health care, and other opportunities by family income and/or family SES also contribute to achievement and developmental gaps. For instance, national data from 2005 and 2007 indicate that about 90 percent of four-year-olds in the top income quintile (top 20 percent) attend some kind of preschool program, compared to 65 percent of those in the two lowest income quintiles (bottom 40 percent). Similarly, about 80 percent of three-year-olds in the top income quintile attend preschool, compared to just 40 percent of those from the middle income and two lowest income quintiles (bottom 60 percent). These factors may contribute to initial school readiness gaps, and the persistence of gaps throughout the elementary school years and beyond.