Whereas reinforcement strengthens behavior, punishment weakens it, reducing the chances that the behavior will occur again. As with reinforcement, there are two kinds of punishment, positive and negative. Positive punishment involves reducing a behavior by delivering an unpleasant stimulus if the behavior occurs. Parents use positive punishment when they spank, scold, or shout at children for bad behavior. Societies use positive punishment when they fine or imprison people who break the law. Negative punishment, also called omission, involves reducing a behavior by removing a pleasant stimulus if the behavior occurs. Parents’ tactics of grounding teenagers or taking away various privileges because of bad behavior are examples of negative punishment.

Considerable controversy exists about whether punishment is an effective way of reducing or eliminating unwanted behaviors. Careful laboratory experiments have shown that, when used properly, punishment can be a powerful and effective method for reducing behavior. Nevertheless, it has several disadvantages. When people are severely punished, they may become angry, aggressive, or have other negative emotional reactions. They may try to hide the evidence of their misbehavior or escape from the situation, as when a punished child runs away from home. In addition, punishment may eliminate desirable behaviors along with undesirable ones. For example, a child who is scolded for making an error in the classroom may not raise his or her hand again. For these and other reasons, many psychologists recommend that punishment be used to control behavior only when there is no realistic alternative.

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