In 2013, Seth Pollak, a child psychologist at the University of Wisconsin at Madison, examined the brain scans of seventy-seven infants from a range of economic backgrounds, following them for three years. He focused on the parts of the brain that are less hereditary and more influenced by the child’s environment. At first, the scans were identical. But by age four, the poor children had developed less “gray matter,” the areas of the brain responsible for impulse control, emotional behavior, problem solving, memory, and other skills critical to learning.
