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

Positive Reinforcement

Reinforcement is defined by its effect on behavior. Specifically, a reinforcer is any stimulus that increases the frequency or probability of a behavior it follows. This is a functional definition. A reinforcer is defined by how it works or functions.

What is the functional definition of reinforcement? How do you know if something is a reinforcer?

One can usually make an educated guess about what reinforcers will work to increase the frequency of behavior. Food usually works with hungry animals. But one never knows for sure what stimulus will function as a reinforcer until it is actually tried. If it increases the frequency or probability of a behavior it follows, then it is a reinforcer, by definition. This is true even if the stimulus does not seem like it should be a reinforcer.

The word positive in positive reinforcement does not refer to the pleasantness of the stimulus. It means a stimulus is added or applied to the situation. Any stimulus that works to increase the frequency of a behavior it follows is a positive reinforcer, even if it does not seem like it should be rewarding. That turns out to be an important insight, as we will see later in the chapter. For example, sometimes a behavior intended as punishment (such as yelling at a child) can function as a reinforcer, making undesirable behaviors more frequent instead of less frequent.

A stimulus intended as a reinforcer may not function as a reinforcer. One must measure results before deciding. If a stimulus actually has the effect of reducing the frequency of the behavior it follows, then it is a punisher, not a reinforcer. Praising a student in class for raising a hand and offering an answer, for example, may be intended by a teacher as encouragement for the student. It is intended as reinforcement. But if the student never again raises his or her hand, then (in effect) the student was punished by this attention.

What are primary and secondary reinforcers? What are examples of each?

Psychologists commonly distinguish between primary and secondary reinforcers. Primary reinforcers are unlearned. They are based on some biological drive or need, such as the need for food, water, attention, or a comfortable temperature.

Secondary reinforcers, by contrast, are learned or symbolic reinforcers. They have value because they can be used to obtain other reinforcers or have been associated with other reinforcers. Money is an example of a secondary reinforcer. You cannot eat or drink money or satisfy any biological need with it, but you can exchange it for other things that do satisfy basic needs. Grades are secondary reinforcers, worthless in themselves, but a means to obtain other reinforcers like pride and fruits of employment after graduation.


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