Reinforcement, positive and negative

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Photo by: pavel siamionov

In psychology, reinforcement refers to the procedure of presenting or removing a stimulus to maintain or increase the likelihood of a behavioral response. (A stimulus is something that causes a response.) Reinforcement is usually divided into two types: positive and negative.

If a stimulus is presented immediately after a behavior and that stimulus increases the probability that the behavior will occur again, the stimulus is called a positive reinforcer. Giving a child candy for cleaning his or her room is an example of a positive reinforcer. The child will learn to clean his or her room (behavior) more often in the future, believing he or she will receive something positive—the candy (stimulus)—in return.

Like positive reinforcement, negative reinforcement increases the likelihood that a behavior associated with it will be continued. However, a negative reinforcer is an unpleasant stimulus that is removed after a behavioral response. Negative reinforcers can range from uncomfortable physical sensations to actions causing severe physical distress. Taking aspirin for a headache is an example of negative reinforcement. If a person's headache (stimulus) goes away after taking aspirin (behavior), then it is likely that the person will take aspirin for headaches in the future.

Reinforcers can also be further classified as primary and secondary. Primary reinforcers are natural; they are not learned. They usually satisfy basic biological needs, such as food, air, water, and shelter. Secondary reinforcers are those that have come to be associated with primary reinforcers. Since money can be used to satisfy the basic needs of food, clothing, and shelter, it is known as a secondary reinforcer. Secondary reinforcers are also called conditioned reinforcers.

Classical conditioning

Reinforcement as a theoretical concept in psychology can be traced back to Russian scientist Ivan P. Pavlov (1849–1936), who studied conditioning and learning in animals in the early 1900s. Pavlov developed the general procedures and terminology for studying what is now called classical conditioning. While studying the salivary functions of dogs, Pavlov noticed that they began to salivate just before he began to feed them. He concluded that salivating in anticipation of the food was a learned response. To further prove this theory, Pavlov conducted an experiment. Just before he gave a dog food, Pavlov rang a bell. After pairing the bell and food several times, Pavlov just rang the bell. He discovered that the sound of the bell alone was enough to make the dogs salivate.

Pavlov labeled the food an unconditional stimulus because it reliably (unconditionally) led to salivation. He called the salivation an unconditional response. The bell tone was a conditioned stimulus because the dog did not salivate in response to the bell until he had been conditioned to do so through repeated pairings with the food. The salivation in response to the bell became a conditioned response.

Classical conditioning thus occurs when a person or animal forms an association between two events. One event need not immediately follow the other. What is important is that one event predicts or brings about the other. An example of classical conditioning in humans can be seen in a trip to the dentist's office. On a person's first visit, the sound of the drill signifies nothing to that person until the dentist begins to use the drill. The pain and discomfort of having a tooth drilled is then remembered by that person on the subsequent visit. The sound of the drill is enough to produce a feeling of anxiety, tensed muscles, and sweaty palms in that person even before the dentist has begun to use the drill.

Operant conditioning

In classical conditioning, the learned responses are reflexes, such as salivating or sweating. The stimuli (food or a dentist's drill) bring about these responses automatically. In operant conditioning, the learned behavioral responses are voluntary. A person or animal learns to perform or not perform a particular behavior based on its positive or negative consequences.

American behavioral psychologist B. F. Skinner (1904–1990) conducted experiments during the 1930s and 1940s to prove that human and animal behavior is based not on independent motivation but on response to reward and punishment. Skinner designed an enclosed, soundproof box equipped with tools, levers, and other devices. In this box, which came to be called the Skinner box, he taught rats to push buttons, pull strings, and press levers to receive a food or water reward.

This type of procedure and the resultant conditioning have become known as operant conditioning. The term "operant" refers to behaviors that respond to, or operate on, the surrounding environment. From his experiments, Skinner developed the theory that humans are controlled (stimulated) solely by forces in their environment. Rewarded behavior (positive reinforcement) is encouraged, and unrewarded behavior (negative reinforcement) is terminated.

[ See also Behavior ]