Reinforcement is a concept used widely in psychology to refer to the method of presenting or removing a stimuli to increase the chances of obtaining a behavioral response. It is usually divided into two categories - positive and negative.
The term reinforcement has been attributed to Russian physiologist and Nobel Prize winner Ivan Pavlov (1849-1936), who developed a theory of classical conditioning, which is the formation of an association between a conditioned stimulus and a response. In particular, he used the terms reinforced stimulus and reinforced reflex.
Reinforcement is also a key concept in behaviorism, a school of psychology, whose pioneer was American scholar B.F. Skinner (1904-1990). In his experiments, Skinner trained rats and pigeons to press a lever to receive food as a reward. His device, a small plastic chamber known as the Skinner Box, aimed to study operant conditioning, learning in which there is contingency between the response and the presentation of the reinforcer. A reinforcer was defined as the stimulus which emerges in response to behavior. In Skinner's experiments, the rats learned very quickly to repeat the action of pressing the lever so that they could receive their reward.
In operant conditioning, behavior is controlled via a number of tools such as reinforcers, punishment and extinction. Reinforcers provide an incentive for the increased frequency of certain behavior. Through punishment, the occurrence of specific conduct becomes rarer. Meanwhile, extinction is the case where behavior does not result in a response.
Some classifications make the difference between positive and negative reinforcement. Researchers claim that the purring of a cat is a positive reinforcer, which encourages people to stroke its fur. Negative reinforcement aims to encourage the occurrence of a behavior by removal of aversive stimulus. In the Skinner Box, rats pressed a lever to stop a loud noise, which is another example of negative reinforcement. According to Skinner, reinforcers were responses from the environment that increase the probability of a behavior being repeated.
Generally, positive reinforcement is regarded as a reward. Negative reinforcement for its part is equal to punishment. However, in contemporary psychology punishment and negative reinforcement are not synonyms, as they provide two different approaches to controlling certain behavior patterns. While negative reinforcement strengthens a behavior, punishment weakens a behavior pattern. Therefore, negative reinforcement is more similar to positive reinforcement than to punishment. Furthermore, in many cases it is difficult to decide whether reinforcement is positive or negative.
Psychologists have also identified so-called primary reinforcers, or biologically determined reinforcers. Sometimes referred to as unconditioned reinforcers, these include sleep, food, water and sex. In contrast, psychologists have also defined conditioned reinforcers, which are neutral stimuli coupled with a primary reinforcer. As a result, the neutral stimuli acquire the same reinforcement properties linked to the primary reinforcer. While primary reinforcers are inborn, conditioned reinforcers are learned. Hence, an example of a conditioned reinforcer is money. Originally, it was not seen as a primary reinforcer but it is closely related to primary reinforcers such as food or water. Bribing children with candies can also create conditioned reinforcers.
Widespread reinforcers in the classroom include praise, attention, grades and recognition. Children learn through their behavior about reinforcement - both positive and negative - and learn to recognize what is acceptable or inappropriate in the school environment. For example, if they are caught smoking they must face the consequences of their actions. Positive reinforcement could come from peers, who admire them for smoking, while negative enforcement can be imposed by teachers who might punish them for taking part in this activity. Self-reinforcement, or the practice of recognizing your own success, is also useful both for children and adults.
Reinforcement theory is also used in the treatment of drug and alcohol addictions. Researchers have found that drugs and alcohol both serve as strong reinforcers that force the user or addict into a habit of seeking and taking them regularly, resulting in a cycle which is difficult to break. Experiments show that drugs which serve as reinforcers for humans have the same effect on animals.
Despite its efficiency, reinforcement has proved to have some shortcomings. The efficient application of reinforcers is highly conditional upon the understanding of its restrictions. Often it is difficult to make the difference between rewards and punishments. Reinforcement can be effective if only all sources of reinforcement are under control. Hence, school, peer groups and family are different sources of reinforcement, which may provide conflicting stimuli and can undermine each other's effect.