B.F. Skinner

 Born in Susquehanna, Pennsylvania, Skinner was an English major in college (Hamilton College) and then pursued psychology (at Harvard). In contrast to Hull, Skinner approached psychology inductively. He proposed an atheoretical methodology which preferred operational definitions to intervening variables.

Best known for his model of learning, Skinner emphasized the importance of what happens after a response. Not S-R, but S-R-C (stimulus-response-consequence), Skinner expanded Thorndike’s law of effect to an entire system of reinforcement.

In place of classical respondent conditioning, Skinner proposed operant conditioning. According to his model, behavior which is followed by a positive reinforcer (reward) is more likely to occur.

Conceding that there are too many stimuli to categorize, Skinner focused on the response and its consequence. Positive reinforcers increase behavior strength; positive punishment decreases behavior temporarily (as long as the punisher is present). Only extinction (the continued absence of a reward) decreases behavior permanently (e.g., if they stop paying you, you don’t go to work). Negative reinforcement (the removal of something bad) increases the likelihood of behavior and negative punishment (the removal of something good) temporarily decreases it.

Note that Skinner did not hypothesize drive, insight or any internal process. He didn’t necessarily deny their existence as much as thought them to be unknowable. For Skinner, if it didn’t impact behavior, whatever went on in the black box of the mind was unimportant.

Basing his findings on animal research (mostly rats and pigeons), Skinner identified five schedules of reinforcement: continuous reinforcement, fixed interval (FI), fixed ratio (FR), variable interval (VI) and variable ratio (VR). Continuous reinforcement is used to shape (refine) a behavior. Every time the subject performs the desired behavior, it is rewarded. Continuous reinforcement leads to quick learning and (after the reinforcement is stopped) quick descent.

Fixed Interval (FI) describes the condition where a certain amount of time must past before a correct response is rewarded (e.g., getting paid every two weeks). FI produces a “scalloped” pattern (the closer it gets to pay day the more often the proper response is given).

Fixed Ratio (FR) requires a certain number of responses to be made before a behavior is rewarded (e.g., 10 widgets must be made before you are paid). In Variable Interval and Variable Ratio schedules of reinforcement, the required amount of time or the number of responses varied. These partially reinforcement schedules (never quite sure when you’ll be rewarded) are quite resistant to extinction.

According to Skinner, rewards should be given appropriately. Parents should reward behaviors they want and ignore (extinguish) behaviors they don’t want. Giving attention to a child (such as when giving a punishment) actually rewards the child with your presence and sends a mixed message. Behavior can be shaped by rewarding successive approximations but practice without reinforcement doesn’t improve performance.

Skinner relied heavily on replication. His experimental evidence did not rely on statistical analyses or large subject pools. He performed carefully designed experiments with strict controls and simply counted the responses.

In an attempt to apply his research to practical problems, Skinner adapted his operant conditioning chamber (he hated the popular title of “Skinner box”) to child rearing. His “Baby Tender” crib was an air conditioned glass box which he used for his own daughter for two and a half years. Although commercially available, it was not a popular success.

During WWII, Skinner designed a missile guidance system using pigeons as “navigators.” Although his system was feasible, the Army rejected it out of hand. The PR problems of pigeon bombers must have been extensive.

Skinner’s also originated programmed instruction. Using a teaching machine (or books with small quizzes which lead to different material), small bits of information are presented in an ordered sequence. Each frame or bit of information must be learned before one is allowed to proceed to the next section. Proceeding to the next section is thought to be rewarding.

Here’s a video lecture on Skinner’s Theory


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