This is the 2007 version. Click here for the 2017 chapter 05 table of contents.


Punishment occurs when a stimulus is applied and has the effect of making a behavior less frequent. Sometimes this is called positive punishment. "Positive" in this context means a stimulus is added. However, few psychologists use the word "positive" when discussing punishment. This would only make beginning students more confused! When you see the word punishment by itself, this means an aversive stimulus is applied .

What is punishment? What is a punisher, by definition?

Punishment, like reinforcement, is defined by its effect. A stimulus that decreases the probability of a behavior it follows is a punisher, by definition. Some surprising things can be punishers. We used the example earlier of praising a student who raises his or her hand in a classroom. If the student never again raises his or her hand, then praising the student was punishment , by definition. Similarly, if you praise a child for drawing pictures, and the child stops drawing pictures, then your praise was punishing rather than reinforcing.

We will provide examples of all these concepts in the next section, on applications of operant conditioning. For now, get acquainted with the basic ideas, especially this concept of defining reinforcement and punishment by their effects. It is one of the more subtle and valuable aspects of operant conditioning. It can give you an "edge" in analyzing certain situations. When you see a behavior get more frequent, you look for the stimulus that follows that behavior, and then assume the stimulus is a reinforcer. This can allow you to identify some weird reinforcers, like yelling at a child, or giving sympathetic attention to a pet. Such reinforcers can establish troublesome behavior patterns, because people do not recognize that a stimulus is functioning as a reinforcer. See, for example, the later section on the punishment trap that occurs when parents ignore children and only pay attention to bad behavior.

Why do some psychologists avoid using the word "reward" as a synonym for "reinforcement"?

Some psychologists caution against using the word reward as a synonym for reinforcement , because a reward is usually intended as a reinforcement but may not actually function as a reinforcer. Whether a reward functions as a reinforcer depends on whether it increases the frequency of behavior it follows. If not, it is not a reinforcer. A reward (something intended as a reinforcer) may actually function as a punisher, if it has the effect of decreasing the frequency or probability of a behavior it follows. The only way to tell is to observe the behavior.

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