Wednesday, April 27, 2016

Thorndike and Skinner



Edward L. Thorndike
1874-1949
Burrhus F. Skinner 
(1904-1990)
Two of the giants in the behaviorist tradition of learning theory were Edward Thorndike and B.F. Skinner. Skinner took Thorndike's work on behavior shaping to another level of complexity. But with greater complexity comes greater potential for being misunderstood, and that's exactly what happened. 

Thorndike observed a century ago that when a behavior is followed by a pleasant effect, the behavior is likely to be repeated in the same situation. Behavior followed by an unpleasant effect is unlikely to be repeated. Thorndike's Law of Effect is easy to understand, due partly to the language he used in describing it. There is no ambiguity in what he meant by pleasant, unpleasant, or effect.

The same cannot be said for B.F. Skinner. He called these same two ways of shaping behavior using pleasant and unpleasant consequences positive reinforcement and positive punishment. Positive didn't mean that they were good or kind or effective, as you might expect; positive simply meant that the effect was added in response to the behavior. Skinner proposed that reinforcement and punishment could also be done by subtracting an effect that was already at work when the behavior was exhibited. He called this negative reinforcement and negative punishment, respectively. Skinner's four ways of shaping behavior are known as the four quadrants of Operant Conditioning. Unfortunately, three of the four are routinely misunderstood.

Positive punishment seems like an oxymoron and negative punishment seems redundant because of Skinner's naming scheme. Those terms are seldom used outside of academic circles. In contrast, positive reinforcement has slipped into common language as a synonym for reward. No harm there. That's exactly what it is. 

But negative reinforcement is problematic. Too often this term is used casually as a synonym for punishment. It's easy to understand why. Negative has many meanings in the English language but the most common connotes undesirability and unpleasantness. Skinner used negative in a mathematical sense. Negative reinforcement is a way of rewarding behavior by taking away an aversive stimulus already acting on the subject. In horse training, for example, you may exert pressure on a horse to get him to move in a certain way, then instantly remove the pressure when he gives an acceptable try. The removal of an aversive is a reward, a pleasant effect. If you have trouble wrapping your mind around this, don't feel bad.

Not only is negative reinforcement incorrectly associated with punishment, it suffers from the association. Many people find punishing their children or animals distasteful and turn to other options. Clicker Training for dogs and horses, for example, uses a clicking sound and food treats to reward correct behavior. Incorrect behavior is ignored, or a different cue is given in hopes of getting a response that can be rewarded. Punishment is reserved for dealing with extremes of undesirable or dangerous behavior.

Learning theory is one of my favorite topics so I have studied Skinner's work many times. I'm always saddened just a bit by the language he chose because I know how often it is misunderstood. By the same token, I love the elegant simplicity of Thorndike's description of his Law of Effect. In the end, words do matter.     

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