Behaviorism:

Skinner was mainly responsible for the development of the philosophy of radical behaviorism and for the further development of applied behavior analysis, a branch of psychology which aims to develop a unified framework for animal and human behavior based on principles of learning. He conducted research on shaping behavior through positive and negative reinforcement and demonstrated operant conditioning, a behavior modification technique which he developed in contrast with classical conditioning.

Contrary to popular belief, Skinner did not advocate the use of punishment. His research suggested that punishment was an ineffective way of controlling behavior, leading generally to short-term behavior change, but resulting mostly in the subject attempting to avoid the punishing stimulus instead of avoiding the behavior that was causing punishment. A simple example of this is the failure of prison to eliminate criminal behavior. If prison (as a punishing stimulus) were effective at altering behavior, there would be no criminality, since the risk of imprisonment for criminal conduct is well established. However, individuals still commit offences, but attempt to avoid discovery and therefore punishment. The punishing stimulus does not stop criminal behaviour. The criminal simply becomes more sophisticated at avoiding the punishment. Positive, rather than negative, reinforcement proves to be more effective in bringing about lasting changes in behaviour.

Superstition in the pigeon:

One of Skinner's most famous and interesting experiments examined the formation of superstition in one of his favourite experimental animals, the pigeon. Skinner placed a series of hungry pigeons in a cage attached to an automatic mechanism that delivered food to the pigeon "at regular intervals with no reference whatsoever to the bird's behaviour". Whatever chance actions each bird had been performing as food was delivered, was strengthened, so the bird continued to perform the same actions:

One bird was conditioned to turn anti-clockwise about the cage, making two or three turns between reinforcements. Another repeatedly thrust its head into one of the upper corners of the cage. A third developed a 'tossing' response, as if placing its head beneath an invisible bar and lifting it repeatedly. Two birds developed a pendulum motion of the head and body, in which the head was extended forward and swung from right to left with a sharp movement followed by a somewhat slower return. ("'Superstition' in the Pigeon", B.F. Skinner, Journal of Experimental Psychology #38, 1947 )

The experiment might be said to demonstrate a sort of superstition. The bird behaves as if there were a causal relation between its behaviour and the presentation of food, although such a relation is lacking. There are many analogies in human behaviour. Rituals for changing one's luck at cards are good examples. A few accidental connections between a ritual and favourable consequences suffice to set up and maintain the behaviour in spite of many non-reinforced instances. The bowler who has released a ball down the alley but continues to behave as if he were controlling it by twisting and turning his arm and shoulder is another case in point. These behaviours have, of course, no real effect upon one's luck or upon a ball half way down an alley, just as in the present case the food would appear as often if the pigeon did nothing -- or, more strictly speaking, did something else. (Ibid.)