Learning helps us adapt to our environment. For example, through classical conditioning we learn to anticipate events, such as being fed or experiencing pain. In his famous studies, Pavlov presented a neutral stimulus just before an unconditioned stimulus, which normally triggered an unconditioned response. After several repetitions, the neutral stimulus alone began triggering a conditioned response resembling the unconditioned response. Pavlov’s work laid a foundation for John Watson’s emerging belief that psychology should study only overt behavior, a position he called behaviorism. The behaviorists’ optimism that learning principles would generalize from one response to another and from one species to another has been tempered. We now know that conditioning principles are cognitively and biologically constrained.

While in classical conditioning we learn to associate two stimuli, in operant conditioning we learn to associate a response and its consequence. Skinner showed that rats and pigeons could be shaped through reinforcement to display successively closer approximations of a desired behavior. Researchers have also studied the effects of positive and negative reinforcers, primary and conditioned reinforcers, and immediate and delayed reinforcers. Critics point to research on latent learning and overjustification to support their claim that Skinner underestimated the importance of cognitive constraints. Although Skinner’s emphasis on external control also stimulated much debate regarding human freedom and the ethics of managing people, his operant principles are being applied in schools, businesses, and homes.

A third type of learning important among higher animals is what Albert Bandura calls observational learning. Children tend to imitate what a model does and says, whether the behavior is prosocial or antisocial.

1. To present the principles and processes involved in classical conditioning.

2. To present the principles and processes involved in operant conditioning.

3. To describe the nature of observational learning.

Early behaviorists such as John Watson argued that psychology should be an objective science and that it should study only overt behavior without reference to mental processes. They believed that the learned behaviors of various organisms could be reduced to universal stimulus-response mechanisms.

Pavlov would repeatedly present a neutral stimulus (such as a tone) just before an unconditioned stimulus (UCS), such as food, which triggered the unconditioned response (UCR) of salivation. After several repetitions, the tone alone (now the conditioned stimulus [CS]) began triggering a conditioned response (CR, salivation). As Pavlov demonstrated, classical conditioning involves respondent behavior–reflexive behavior that occurs as an automatic response to some stimulus.

Responses are acquired, initially learned, best when the CS is presented half a second before the UCS. Conditioned responses weaken if they are not reinforced (extinction), but they may reappear after a rest (spontaneous recovery). Furthermore, responses may be triggered by stimuli similar to the conditioned stimulus (generalization), but not by dissimilar stimuli (discrimination).

The behaviorists’ optimism that learning principles would generalize from one response to another and from one species to another has been tempered. Conditioning principles are constrained by the biological predispositions of each species. For example, rats are biologically prepared to learn associations between the taste of a particular food and the onset of illness, but not between a loud noise and an illness.

Pavlov’s work laid a foundation for John Watson’s emerging belief that, to be an objective science, psychology should study only overt behavior, without considering unobservable mental activity. Pavlov taught us that principles of learning apply across species, that significant psychological phenomena can be studied objectively, and that conditioning principles have important applications.

Classical conditioning principles provide important insights into drug abuse and how it may be overcome. Classical conditioning works on the body’s disease-fighting immune system. For example, when a particular taste accompanies a drug that influences immune responses, the taste by itself may come to produce those immune responses. Watson’s "Little Albert" study demonstrated how classical conditioning may underlie specific fears. Today, psychologists use extinction procedures to control our less adaptive emotions and condition new responses to emotion-arousing stimuli.

Operant conditioning involves operant behavior that actively operates on the environment to produce stimuli. Skinner’s work elaborated a simple fact of life that Edward Thorndike called the law of effect: Rewarded behavior is likely to recur. In his experiments involving an operant chamber (Skinner box), Skinner used shaping, a procedure in which rewards, such as food, guide an animal’s natural behavior toward a desired behavior. By rewarding responses that are ever closer to the final desired behavior, and ignoring all other responses, researchers can gradually shape complex behaviors.

When the desired response is reinforced every time it occurs, continuous reinforcement is involved. More common are partial (intermittent) reinforcement schedules. Fixed-ratio schedules reinforce behavior after a set number of responses; variable-ratio schedules provide reinforcers after an unpredictable number of responses. Fixed-interval schedules reinforce the first response after a fixed time interval and variable-interval schedules reinforce the first response after varying time intervals. Partial reinforcement produces slower acquisition of the target behavior than does continuous reinforcement, but the learning is more resistant to extinction.

Many psychologists have criticized Skinner for underestimating the importance of cognitive and biological constraints. For example, rats exploring a maze seem to develop a mental representation (a cognitive map) of the maze even in the absence of reward. Their latent learning becomes evident only when there is some incentive to demonstrate it.

The cognitive perspective has also led to an important qualification concerning the power of rewards. The overjustification effect indicates that people may come to see rewards, rather than intrinsic interest, as the motivation for performing a task. By undermining intrinsic interest, rewards can carry hidden costs.

As with classical conditioning, an animal’s natural predispositions constrain its capacity for operant conditioning.

Skinner has been criticized for repeatedly insisting that external influences, not internal thoughts and feelings, shape behavior and for urging the use of operant principles to control people’s behavior. Critics argue that he dehumanized people by neglecting their personal freedom and by seeking to control their actions. Skinner countered: People’s behavior is already controlled by external reinforcers, so why not administer those consequences for human betterment?

Operant principles have been applied in a variety of settings. For example, in schools, online testing systems and interactive student software embody the operant ideal of individualized shaping and immediate reinforcement. In businesses, positive reinforcement for jobs well done has boosted employee productivity. In the home, people’s use of energy has been decreased by altering the consequences and providing feedback.

Among higher animals, especially humans, learning does not occur through direct experience alone. Observational learning also plays a part. The process of observing and imitating a specific behavior is often called modeling.

In Bandura’s famous experiments, children who observed an adult’s aggressive outburst toward a large inflated Bobo doll were subsequently much more likely to lash out at the doll themselves. Bandura’s studies suggest that antisocial models may have antisocial effects. The good news is that prosocial (positive, helpful) models can have prosocial effects.