The number of people receiving a high school and college education increased dramatically from 1920 to 1960. Because very few jobs were available to teens coming out of eighth grade, there was an increase in high school attendance in the 1930s. The progressive movement in the United States took off at this time and led to the idea of progressive education. John Flanagan, an educational psychologist, developed tests for combat trainees and instructions in combat training. In 1954 the work of Kenneth Clark and his wife on the effects of segregation on black and white children was influential in the Supreme Court case Brown v. Board of Education. From the 1960s to present day, educational psychology has switched from a behaviorist perspective to a more cognitive based perspective because of the influence and development of cognitive psychology at this time.