B.F. Skinner was an American psychologist born in 1904 who developed the theory of operant conditioning. He believed that behavior is shaped by its consequences through reinforcement or punishment. Skinner conducted experiments using Skinner boxes to demonstrate how schedules of reinforcement can modify behavior. His work showed how intermittent reinforcement can encourage persistent behaviors like gambling. Skinner also developed the technique of shaping to gradually modify behaviors through reinforcement. His research influenced education and how behaviors are learned through reinforcement and punishment.