Reinforcement Theory proposes that social behavior is governed by external events (events outside the human psyche). The basic premise is that people will more likely perform a specific behavior if it is followed directly by the occurrence of something pleasurable or by the removal of something aversive. Additionally, the opposite premise is also included in the theory, but tends not to have as strong of an impact on behavior: people will less likely perform a specific behavior if it is followed by something aversive or the removal of something pleasurable. One of the benefits of this approach to understanding human (and animal) behavior is that the events are observable, as compared with cognitive theories of human behavior.
The external events that play a role in reinforcement theory are referred to as stimuli. They include any event that leads to an alteration or change in behavior. The change in behavior induced by a stimulus is a response.
Reinforcement theory has been operationalized in a process called operant conditioning. Positive reinforcement is the contingent presentation of a stimulus following a response, resulting in an increased likelihood of the response occurring in the future. Negative reinforcement is the contingent withdrawal of a stimulus following a response, resulting in an increased likelihood of the response occurring in the future. Unconditioned reinforcement, also called primary reinforcement, is the presentation of stimuli that are inherently reinforcing, such as affection, food, sex, or sleep. Conditioned reinforcement, also called secondary reinforcement, is the presentation of a stimulus which has acquired reinforcing power through association with primary reinforcers. Social reinforcement is a form of conditioned reinforcement in which the reinforcer involves some sort of interaction with others. Positive punishment is the contingent presentation of a stimulus following a response, resulting in a decreased likelihood of the response occurring in the future, whereas negative punishment is the contingent withdrawal of a stimulus following a response, resulting in a decreased likelihood of the response occurring in the future.
Successive approximation is the presentation of reinforcers after increasingly accurate productions of the desired response. For example, in training rats or pigeons to depress a lever or peck a key, reinforcement will initially be contingent on simply turning toward the lever or key. As training progresses, the response reinforced becomes progressively more like the response desired by the trainer (i.e., actually pecking the key). Behaviours developed through the reinforcement of successive approximations to the eventual desired behaviour are called shaped behaviours and the process is called shaping.
The study of reinforcement has produced strong, replicable results. The effects of different schedules of reinforcement (i.e., variations in the rate or ratio of reinforcement) have been extensively studied. Some of these schedules include:
- Continuous reinforcement, in which a reinforcer is presented after every desired response,
- Fixed ratio, in which a reinforcer is presented after every nth response,
- Fixed interval, in which a reinforcer is presented after the passage of a specified length of time from the beginning of training or from the presentation of the last reinforcer, provided a response has been made during the period,
- Variable ratio, in which the number of responses between reinforcers varies, but on the average equals a predetermined number
- Variable interval, in which the time between reinforcers varies, but on the average equals a predetermined time.
Ratio schedules produce higher rates of responding than interval schedules, with variable ratio scales producing the highest rates of response. Variable ratio schedules produce the greatest resistance to extinction, which is the decline in response strength following the cessation of reinforcement.
This theoretical approach to understanding human behavior has been criticized on a number of levels. First, it has been criticized as employing circular reasoning, since it appears to argue that response strength is increased by reinforcement while defining reinforcement as something which increases response strength. However, non-circular definitions have been proposed. For example, reinforcement can be defined as consummatory behaviour contingent on a response.
Another limitation of this theoretical approach is that it portrays individuals as primarily reacting to environmental stimuli rather than as initiating behavior based on imaginative or creative thought. In short, it downplays the role of cognition in human behavior. As a result, this theoretical approach downplays the influence of other motivations in explaining human behavior. Additionally, reinforcement theory cannot explain selfless behavior and altruism, instances where the individual acts to their own detriment in order to help another.