An adherent to Watson's theory of behaviorism, B.F. Skinner was able to demonstrate how one can modify behavior through a process he called "shaping." In contrast to pure classical conditioning, Skinner utilized positive and negative reinforcement to cause behavior.

Utilizing a contraption that became known as "Skinner's Box" he demonstrated how he could shape the behavior of pigeons by reinforcing their behavior.

"By discovering the causes of behavior we can dispose of the imagined internal cause."
- B.F. Skinner.