Introduction to Reinforcement
Reinforcement is a behavioral psychology term related to operant conditioning, that refers to any consequence to a behavior that strengthens the likelihood for that behavior to be exhibited in the future. The strengthening effect on the response via the stimulus can manifest in multiple ways, including higher frequency, longer duration, greater magnitude, and short latency of response. Reinforcers come in many different varieties, including positive and negative, primary and secondary, and conditioned and unconditioned, but all of them increase the probability of behavior after administration.
History of Reinforcement Principles
B.F. Skinner was one of the first psychologists to study reactions to reinforcement principles in animal test subjects, measuring the effectiveness of reinforcers on behavioral responses, rather than on subjective criteria. It was his belief that all of human and animal behavior could be explained by observable patterns in the physical world that were learned over time. Much of this theory was learned from E.L. Thorndike who coined the law of effect, which stated that the tendency to perform an action is increased when rewarded, and weakened otherwise. Skinner took that idea one step further, and utilized it to learn how to encourage one specific behavior or target over another. Using reinforcement techniques, he was able to discover methods to encourage long-term behavioral modification that are still in use today.
Types of Reinforcement
Operant conditioning can be enacted using one of two methods: reinforcement, which increases the frequency of a behavior; and punishment, which decreases the frequency of a behavior. Reinforcers and punishments come in two basic valences: either positive, adding something to a situation; or negative, taking something away. Positive reinforcers add a wanted or pleasant stimulus to increase or maintain the frequency of a behavior. Negative reinforcers remove an unwanted or unpleasant stimulus to increase or maintain the frequency of a behavior. Positive punishments add an aversive stimulus to decrease a behavior or response. Negative punishments remove a pleasant stimulus to decrease a behavior of response. All of these methods can manipulate the behavior of a subject, but each works in a unique fashion (Figure 1).
Primary and Secondary Reinforcers
Skinner also used what he called primary and secondary reinforcers to train his subjects. By differentiating between the two types, he was able to add an element of complexity to his experiments and learn more about how habits and behaviors are acquired.
A primary reinforcer, also called an unconditioned reinforcer, is a stimulus that does not require deliberate pairing to function as a reinforcer. Most animals and humans attain these reinforcers through evolution, or other methods of species survival. They include items such as food, water, sleep, and sex. Some primary reinforcers, such as drugs and alcohol, merely mimic the effects of other reinforcers. Primary reinforcers have been found to remain stable throughout life and across individual organisms. Their reinforcing value varies, however, due to the variety among organisms, such as in genetics or experiences. For example, favorite types of food and drink can differ greatly among human beings.
A secondary reinforcer, also called a conditioned reinforcer, is a stimulus that requires pairing with another stimulus to function as a reinforcer. The paired stimulus can be either a primary reinforcer, or another already-acquired secondary reinforcer. Before pairing, the secondary reinforcer has no meaningful effect on a subject. Money is one of the best examples of a secondary reinforcer as it has come to be paired with many other reinforcers, and is responsible for much of human behavior. As with primary reinforcers, secondary reinforcers can vary among subjects. Unlike primary reinforcers, however, secondary reinforcers can change over time as learning occurs.