During this time, which Skinner later called "the dark year," he chanced upon a copy of Bertrand Russell's Philosophy in which Russell discusses the behaviorist philosophy of psychologist John B. Watson. At the time, Skinner had begun to take more interest in the actions and behaviors of those around him, and some of his short stories had taken a "psychological" slant. He decided to abandon literature and seek admission as a graduate student in psychology at Harvard University (which at the time was not regarded as a leading institution in that field).

Skinner received a Ph.D. from Harvard in 1931 and remained at that institution as a researcher until 1936. He then taught at the University of Minnesota at Minneapolis and later at Indiana University before returning to Harvard as a tenured professor in 1948. He remained there for the rest of his career. Skinner was granted numerous awards in his lifetime. In 1968, he received the National Medal of Science by President Lyndon B. Johnson.

Three years later, he was awarded the Gold Medal of the American Psychological Foundation, and in 1972, he was given the Humanist of the Year Award of the American Humanist Association. Just eight days before his death, he received the first Citation for Outstanding Lifetime Contribution to Psychology by the American Psychological Association (Epstein, 1997).

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.

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. Reinforcement, both positive and negative (the latter of which is often confused with punishment), 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 favorite 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 counter-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.
—B.F. Skinner (1947). "'Superstition' in the Pigeon". Journal of Experimental Psychology 38.

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.

Social engineering
Skinner is popularly known mainly for his controversial books Walden Two and Beyond Freedom and Dignity. Walden Two describes a visit to an imaginary utopian commune in the 1940s United States, where the productivity and happiness of the citizens is far in advance of that in the outside world due to their practice of scientific social planning and the use of operant conditioning in the raising of children. Walden Two, like Thoreau's Walden, champions a lifestyle that doesn't foster competition and social strife and doesn't support war. It favors and encourages a lifestyle of minimal consumption, rich social relationships, personal happiness, satisfying work and leisure.

Beyond Freedom and Dignity advanced the thesis that obsolete social concepts, like free will and human dignity (by which Skinner meant belief in individual autonomy) stood in the way of greater human happiness and productivity. Skinner was just as opposed to inhumane treatment and bad government as many, and perhaps more than some, but he argued that the champions of freedom went so far as to deny causality in human action so they could champion the "free person." So the champions of freedom were, in a sense, the enemies of a scientific way of knowing. There is a rough parallel here to the book "Higher Superstition" in the opposition to scientific knowledge, except Skinner here is being much more general.

Dignity is the practice of giving individuals credit for their actions. To say "Skinner is brilliant" means that Skinner is an originating force. If Skinner is right, he is merely the focus of his environment. He is not an originating force and he had no choice in saying the things he said or doing the things he did. Skinner's environment and genetics allowed and made him write his book. This is not to say that that means it is not true. The environment and genetics of the advocates of freedom and dignity make them fight the reality of their activity being grounded in determinism.

Rumors
One often-repeated story claims that Skinner ventured into human experiments by raising his daughter Deborah in a Skinner box, which led to her life-long mental illness and a bitter resentment towards her father.

In fact, the Heir Conditioner, a term for Skinner's baby crib, was heated, cooled, had filtered air, allowed plenty of space to walk around in, and was much like a miniature version of a modern home. It was designed to make the baby more confident, more comfortable, less sick, less prone to cry, and so on. Reportedly it had some success in these goals.

Psychologist and author Lauren Slater published a book, "Opening Skinner's Box," in 2004, which mentioned claims that Deborah unsuccessfully sued her father for abuse and later committed suicide. The book then immediately pointed out that the reality was rather different. However, at least one reviewer misread the book and reported it as making the claims without correcting them. In response, Deborah Skinner herself came forward to publicly denounce the story as nothing more than hearsay and presumably to vouch for her own continued existence. She blasted Lauren Slater's book for repeating this urban legend as being vicious and harmful; she was presumably relying on someone else's inaccurate depiction of the book's contents. See "I was not a lab rat" in the Guardian Unlimited Friday March 12, 2004 for the full text of Deborah's denunciation.

As much as anything, this episode showed how rumours come into being - even now, journalists still write articles about whether this book was in support of, rather than against, the original rumours about Skinner's treatment of his children.

Political Views
Skinner's political writings emphasized his hopes that an effective and humane science of behavioral control - a behavioral technology - could solve human problems which were not solved by earlier approaches or were actively aggravated by advances in physical technology such as the atomic bomb. One of Skinner's stated goals was to prevent humanity from destroying itself.

Skinner was sometimes accused of being a totalitarian by his critics, and it is not difficult to see why. In addition to his aspirations to state design, Skinner was a determinist, believing that all of our behavior is profoundly determined and influenced by the environment.

Skinner saw the problems of political control not as a battle of domination versus freedom, but as choices of what kinds of control were used for what purposes. Skinner opposed the use of coercion, punishment and fear and supported the use of positive reinforcement.

Skinner's book Walden Two presents a vision of a decentralized, localized society which applies a practical, scientific approach and futuristically advanced behavioral expertise to peacefully deal with social problems. Skinner's utopia, like every other utopia or dystopia, is both a thought experiment and a rhetorical work.

Skinner answers a problem that exists in many utopian novels "What is the Good Life?" Skinner answers that it is a life of friendship, health, art, a healthy balance between work and leisure, a minimum of unpleasantness, and a feeling that one has made worthwhile contributions to one's society.

Additionally Skinner felt behavioral technology would offer alternatives to coercion, good science applied right would help society, and we would all be better off if we cooperated with each other peacefully. Skinner's novel has been described by Skinner as "my New Atlantis" referring to Bacon's utopia.

Intellectual opponents, such as Noam Chomsky, in their attempt to show Skinner wrong, have equated Skinner's philosophic determinism with political oppression. Skinner has often been equated to political and social positions he never espoused and even explicitly objected to.

Trivia
According to a photo caption at the site of Los Horcones community (which was inspired by Skinner's Walden Two), in his youth Skinner used to swim in Thoreau's Walden Pond.