Brain Rules for Baby: How to Raise a Smart and Happy Child from Zero to Five

by John Medina

In 1962, researchers wanted to test the effects of an early-childhood training program they had designed. Kids in Ypsilanti, Michigan, were randomly assigned to one of two groups. The first attended the preschool program (which eventually became a model for other preschool programs nationwide, including Head Start). The second group did not. The differences between the two groups powerfully illustrate the importance of a child’s early years. The kids in the program academically outperformed the controls in virtually every way you can measure performance, from IQ and language tests in the early years to standardized achievement assessments and literacy exams in the later years. To cite just one example (performance on the 1970 California Achievement Test), kids in the program scored far better than the controls: a whopping 49 percent vs. 15 percent. Among girls, though not boys, more graduated from high school (84 percent vs. 32 percent). As adults, those who had been in the program were less likely to commit crimes and more likely to hold steady jobs. They made more money, more often had a savings account, and were more likely to own a home. Economists calculated that the return on society’s investment in such a program was 7 to 10 percent, higher than what you’d historically get in the stock market. If each tax dollar was invested from age 4 through 65, it would return “in present-value terms $7 to $12 back to society,” one analysis said.