Reinforcement is a term used in operant conditioning to refer to anything that increases the likelihood that a response will occur. Note that reinforcement is defined by the effect that it has on behavior - it increases or strengthens the behavior.
For example, reinforcement might involve presenting praise (the reinforcer) immediately after a child puts away her toys (the response). By reinforcing the desired behavior with praise, the girl will be more likely to perform the same actions again.
Types of Reinforcement
Reinforcement can include anything that strengthens or increases a behavior, including stimuli, events and situations. In a classroom setting, for example, types of reinforcement might include praise, getting out of unwanted work, token rewards, candy, extra playtime and fun activities.
There are two major categories of reinforcement:
- Primary reinforcement, sometimes referred to as unconditional reinforcement, occurs naturally and does not require learning in order to work. Primary reinforcers often have an evolutionary basis in that they aid in the survival of the species. Examples of primary reinforcers include food, air, sleep, water and sex. Genetics and experience may also play a role in how reinforcing such things are. For example, while one person might find a certain type of food very rewarding, another person may not like that food at all.
- Secondary reinforcement, also known as conditioned reinforcement, involves stimuli that have become rewarding by being paired with another reinforcing stimulus. For example, when training a dog, praise and treats might be used as primary reinforcers. The sound of a clicker can be associated with the praise and treats until the sound of the clicker itself begins to work as a secondary reinforcer.
In operant conditioning, there are two different types of reinforcement:
- Positive reinforcement involves the addition of something to increase a response, such as giving a bit of candy to a child after she cleans up her room.
- Negative reinforcement involves removing something in order to increase a response, such as canceling a quiz if students turn in all of their homework for the week. By removing the aversive stimulus (the quiz), the teacher hopes to increase the occurrence of the desired behavior (completing all homework).
The Strength of the Response
How and when reinforcement is delivered can affect the overall strength of a response. This strength is measured by the persistence, frequency, duration and accuracy of the response after reinforcement is halted.
In situations when the presentation of reinforcement is controlled, such as during training, the timing of when a reinforcer is presented can be manipulated. During the early stages of learning, continuous reinforcement is often used. This schedule involves reinforcing a response each and every time it occurs.
Once a behavior has been acquired, it is often a good idea to switch to a partial reinforcement schedule. The four main types of partial reinforcement are:
- Fixed-ratio schedules: Reinforcing a behavior after a specific number of responses have occurred.
- Fixed-interval schedules: Reinforcing a behavior after a specific period of time has elapsed.
- Variable-ratio schedules: Reinforcing the behavior after an unpredictable number of responses.
- Variable-interval schedules: Reinforcing the behavior after an unpredictable period of time has elapsed.
Ferster, C.B., & Skinner, B.F. (1957). Schedules of reinforcement. New York: Appleton-Century-Crofts.
Skinner, B. F. (1974). About Behaviorism. New York: Knopf.