Writer, Psychologist. Burrhus Frederic Skinner, commonly known as B. F. Skinner, was an American psychologist, behaviorist, author, inventor, and social philosopher. While a graduate student at Harvard University in the late 1920s, he studied animal behavior, including positive and negative reinforcement, punishment, and memory. He created a box with a simple control that could be manipulated by animals, such as a lever or disk, and trained animals to respond to stimuli with rewards (such as food) or punishment (such as shocks). This box is known as an operant conditioning chamber, or a Skinner Box. He received a PhD from Harvard in 1931, and remained there as a researcher until 1936. He publicized his behavioral theory in his first book, Behavior of Organisms, published in 1938, describing how environment controls behavior. He taught at the University of Minnesota at Minneapolis and later at Indiana University, where he was chair of the psychology department from 1946–1947, before returning to Harvard as a tenured professor in 1948. In his book Science and Human Behavior, published in 1953, he redefined negative reinforcement. Positive reinforcement is the strengthening of behavior by the occurrence of some event, and negative reinforcement is the strengthening of behavior by the removal or avoidance of some aversive event. He believed that effective teaching must be based on positive reinforcement which is, he argued, more effective at changing and establishing behavior than punishment, as the main thing people learn from being punished is how to avoid punishment. This view had implications for the practice of rote learning and punitive discipline in education. He also wrote Walden Two and Beyond Freedom and Dignity, for which he made the cover of TIME Magazine. Walden Two describes a fictional "experimental community" in 1940s United States, where the residents practice scientific social planning and use operant conditioning in raising their children. His public exposure increased in the 1970s, and he remained active in social causes until his death. Ten days before his death, he was given the lifetime achievement award by the American Psychological Association and gave a talk in an auditorium concerning his work.