Thorndike and Watson rejected introspective methods and wanted to restrict psychology to experimental methods . Skinner 's research focused on Operant conditioning . Its main influences were Ivan Pavlov , who investigated classical conditioning although he did not necessarily agree with Behaviorism or Behaviorists , Edward Lee Thorndike , John B. Watson who rejected introspective methods and sought to restrict psychology to experimental methods , and B.F. Skinner who conducted research on operant conditioning .