Skinner carried out carefully controlled experiments on the behavior of individual laboratory rats in the early 1930s (Leigland, 2010). Thorndike's early studies of animal behavior and Watson's definition of behavioral science established the potential value of experimental research with animals (Leslie, 2002). Skinner was one of the major proponents of behaviorism. He studied how learning is affected by changes in environments and sought to demonstrate that behavior can be predicted and controlled (Weegar & Pacis, 2012). Skinner believed that all behavior was determined (Ardila, 2012) and that “free will” did not exist (Weegar & Pacis, 2012). He invented the famous Skinner box in which a white mouse was placed in an enclosure with a lever where, when pushed by the mouse, it caused a small pellet of food to be dispensed into a cup located under the lever which was intended to reinforce the behavior. Skinner called his approach “experimental analysis of behavior” and this behavior became known as operant conditioning (Leslie,