The principle of reinforcement is a psychological concept based on the idea that the consequences of an action will influence future behavior. Rewarding behavior is considered reinforcement, because it teaches the subject that the behavior is desired, and encourages the subject to repeat it. Punishing a behavior, on the other hand, teaches the subject that the behavior is not desired, and should not be repeated. Punishment and reinforcement are an important part of operant conditioning, used in many psychological experiments.
In the case of both reinforcement and punishment, the experimenter makes changes to the environment of the subject. It is important for the researcher to have total control over the environment, as other factors can influence the behavior of the subject, potentially throwing off the operant conditioning. The most successful reinforcement training occurs in a laboratory, which has closed conditions, but reinforcement is also applied in animal training. Many educators use the principle when working with children.
There are actually two types of reinforcement: positive reinforcement and negative reinforcement. Positive reinforcement refers to introducing a new stimulus to the subject's environment in order to reward desired behavior. For example, a child might be given a balloon after behaving well at the dentist, or a rat might learn to press a bar for a treat. Positive reinforcement associates a pleasant outcome with the desired outcome. Negative reinforcement, on the other hand, involves removing an unpleasant stimulus from the environment. For example, a mouse entering a cage with an electrified floor would quickly learn to press a button if the current was stopped every time the button was pressed.
Negative reinforcement is used in escape and avoidance conditioning. In escape conditioning, the subject learns to quickly remove him or herself from a situation where the negative stimulus exists, much as people evacuate a building with a screaming fire alarm. Avoidance conditioning involves learning to avoid the potentially unpleasant situation altogether, and the most classic example of avoidance conditioning is eating when you expect to be hungry, to avoid the unpleasant sensation of hunger.
Likewise, punishment is divided into positive and negative aspects. In a positive punishment situation, something unpleasant is introduced the the environment, such as a spanking for a misbehaving child. Negative punishment removes a pleasant thing from the environment, much as a parent might take ice cream away from a screaming child. Generally, punishment is not deemed as effective as reinforcement in teaching behaviors, as it can be confusing to the subject when not applied correctly.