Victor bautista and matthew montejo

I-----------------------------------OL~~~~ CIa sical

Does the mere sight of the golden arches in front of McDonald 's make you feel pangs of hunger and think about hamburgers? If it does, you are displaying an elementary form oflearning called clas- sical conditioning. Classical conditioning helps explain such diverse phenomena as crying at the sight of a bride walking down the aisle, fearing the dark, and falling in love. .

Classical conditioning is one of a number of different types of learning that psychologists have identified, but a general definition encompasses them all: learning is a relatively permanent change in behavior that is brought about by experience.

We are primed for learning from the beginning of life. Infants exhibit a primitive type of learning called habituation. Habituation is the decrease in response to a stimulus that occurs after repeated presentations of the same stimulus. For example, young infants may initially show interest in a novel stimulus, such as a brightly colored

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toy, but they will soon lose interest if they see the same toy over and over. (Adults exhibit habituation, too: newlyweds soon stop noticing that they are wearing a wedding ring.) Habituation permits us to ignore things that have stopped providing new information. Most learning is considerably more complex than habituation, and the study

of learning has been at the core of the field of psychology. Although philoso- phers since the time of Aristotle have speculated on the foundations of learn- ing, the first systematic research on learning was done at the beginning of the twentieth century, when Ivan Pavlov (does the name ring a belli) developed the framework for learning called classical conditioning.

»LOl The Basics of Classical Conditioning

LEARNINC OUTCOMES

15.1 Describe the basics of classical conditioning and how they relate to learning.

15.2 Give examples of applying conditioning principles to human behavior.

15.3 Explain extinction. 15.4 Discuss stimulus generalization and discrimination.

Learning A relatively permanent change in behavior brought about by experience.

In the early twentieth century, Ivan Pavlov, a famous Russian physiologist, had been studying the secretion of stomach acids and salivation in dogs in response to the ingestion of varying amounts and kinds of food. While doing that he observed a curious phenomenon: sometimes stomach secretions and salivation would begin in the dogs when they had not yet eaten any food. The mere sight of the experimenter who normally brought the food, or even the sound of the experimenter's footsteps, was enough to produce salivation in the dogs.

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_ vlov's genius lay in his ability to recognize the implications of this discov- . He saw that the dogs were responding not only on the basis of a biological

(hunger), but also as a result oflearning-or, as it came to be called, classi- " conditioning, Classical conditioning is a type of learning in which a neu-

_""- timulus (such as the experimenter's footsteps) comes to elicit a response -=-er being paired with a stimulus (such as food) that naturally brings about

---- response. To demonstrate classical conditioning, Pavlov (1927) attached a tube - e salivary gland of a dog, allowing allow him to measure precisely

--". dog's salivation. He then rang a bell and, just a few seconds later, pre- - ed the dog with meat This pairing occurred repeatedly and was care-

planned so that, each time, exactly the same amount of time elapsed een the presentation of the bell and the meat At first the dog would

ivate only when the meat was presented, but soon it began to salivate .- the sound of the bell. In fact, even when Pavlov stopped presenting the =eat, the dog still salivated after hearing the sound. The dog had been

sically conditioned to salivate to the bell. As you can see in Figure 1, the basic processes of classical conditioning

-' at underlie Pavlov's discovery are straightforward, although the terrni- nolog'y he chose is not simple. Consider first the diagram in Figure 1A.

efore conditioning, there are two unrelated stimuli: the ringing of a bell d meat. We know that normally the ringing of a bell does not lead to

: livation but to some irrelevant response, such as pricking up the ears perhaps a startle reaction. The bell is theref06e called the neutral

stimulus because it is a stimulus that, before conditioning,does not naturally ring about the response in which we are interested. We also have meat, which

naturally causes a dog to salivate-the response we are interested in condi- ioning. The meat is considered an unconditioned stimulus, or UCS, because

food placed in a dog's mouth automatically causes salivation to occur. The response that the meat elicits (salivation) is called an unconditioned response, or UCR-a natural, innate, reflexive response that is not associated with previous learning. Unconditioned responses are always brought about by the presence of unconditioned stimuli. "'\

Figure 1B illustrates what happens during conditioning. The bell is rung just before each presentation of the meat. The goal of conditioning is for the dog to associate the bell with the unconditioned stimulus (meat) and therefore to bring about the same sort of response as the unconditioned stimulus. After a number of pairings of the bell and meat, the bell alone causes the dog to salivate.

Ivan Pavlov (center) developed the principles of classical conditioning.

Classical conditioning A type of learning in which a neutral stimulus comes to bring about a response after it is paired with a stimulus that naturally brings about that response.

Neutral stimulus A stimulus that, before conditioning, does not naturally bring about the response of interest.

Unconditioned stimulus (UeS) A'stirnulus that naturally brings about a particular response without having been learned.

unconditioned response (UCR) A response that is natural and needs no training (e.g., salivation at the smell of food).

STUDY ALERT Figure 1 (on the next page)

can help you learn and understand the process (and

terminology) of classical conditioning, which can be

confusing.

Module lS CLASSICAL CONDITIONING 163

Before Conditioning

Neutral stimulus Response unrelated to meat I

4.'Sound of bell ••~,~... . Unconditioned stimulus (UCS) Unconditioned response (UCR)

I "I ~~

Meat

During Conditioning

Unconditioned response (UCR)Neutral stimulus

Sound of bell

Meat

FIGU E 1 The basic process of classical conditioning. (A)Before conditioning. the ringing of a bell does not bring about salivation-making the bell a neutral stimulus, In contrast. meat naturally brings about salivation. making the meat an unconditioned stimulus and salivation an unconditioned response. (B)During conditioning. the bell is rung just before the presentation of the meat. (C)Eventually. the ringing of the bell alone brings about salivation. We now can say that conditioning has been accomplished: the previously neutral stimulus of., the bell now is a conditioned stimulus that brings about the conditioned response of salivation.

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When conditioning is complete, the bell has evolved from a neutral stimulus to what is now called a conditioned stimulus, or CS. At this time, salivation that occurs as a response to the conditioned stimulus (bell) is considered a conditioned response, or CR. This situation is depicted in Figure Ie. After conditioning, then, the conditioned stimulus evokes the conditioned response.

The sequence and timing of the presenta- tion of the unconditioned stimulus and the conditioned stimulus are particularly impor- tant. Like a malfunctioning warning light at a railroad crossing that goes on after the train has passed by, a neutral stimulus that follows an unconditioned stimulus has little chance of becoming a conditioned stimu- lus. However, just as a warning light works best if it goes on right before a train passes, a neutral stimulus that is presented just before the unconditioned stimulus is most apt to result in successful conditioning (Bitterman, 2006).

Although the terminology Pavlov used to describe classical conditioning may seem confusing, the following summary can help make the relationships between stimuli and responses easier to understand and remember:

• Conditioned = learned. Unconditioned = not learned.

• An unconditioned stimulus leads to an unconditioned response. Unconditioned stimulus-unconditioned response pairings are unlearned and untrained. During conditioning, a previously neu- tral stimulus is transformed into the conditioned stimulus. A conditioned stimulus leads to a con- ditioned response, and a conditioned stimulus-conditioned response pair- ing is a consequence of learning and training.

• An unconditioned response and a con- ditioned response are similar (such as salivation in Pavlov's experiment), but the unconditioned response occurs naturally, whereas the conditioned response is learned.

What do you think would happen if a dog that had become classically condi- tioned to salivate at the ringing of a bell never again received food when the bell was rung? The answer lies in one of the basic phenomena of learning: extinc- tion. Extinction occurs when a previously conditioned response decreases in frequency and eventually disappears.

To produce extinction, one needs to end the association between condi- tioned stimuli and unconditioned stimuli. For instance, if we had trained a dog to salivate (the conditioned response) at the ringing of a bell (the conditioned

02 Applying Conditioning Principles to Human Behavior

Conditioned stimulus (CS) A once- neutral stimulus that has been paired with an unconditioned stimulus to bring about a response formerly caused only by the unconditioned stimulus.

Conditioned response (CR) A response that, after conditioning, follows a previously neutral stimulus (e.g., salivation at the ringing of a bell).

Extinction A basic phenomenon of learning that occurs when a previously conditioned response decreases in frequency and eventually disappears.

Although the initial conditioning experiments were carried out with ani- mals, classical conditioning principles were soon found to explain many aspects of everyday human behavior. Recall, for instance, the earlier illus- tration of how people may experience hunger pangs at the sight of McDon- ald's golden arches. The cause of this reaction is classical conditioning: the previously neutral arches have become associated with the food inside the restaurant (the unconditioned stimulus), causing the arches to become a conditioned stimulus that brings about the conditioned response of hunger.

Emotional responses are especially likely to be learned through classi- cal conditioning processes. For instance, how do some of us develop fears of mice, spiders, and other creatures that are typically harmless? In a now infamous case study, psychologist John B. Watson and colleague Rosalie Rayner (1920) showed that classical conditioning was at the root of such fears by condi- tioning an l l-month -old infant named Albert to be afraid of rats. "Little Albert," like most infants, initially was frightened by loud noises but had no fear of rats.

In the study, the experimenters sounded a loud noise just as they showed Little Albert a rat. The noise (the unconditioned stimulus) evoked fear (the unconditioned response). However, after just a few pairings of noise and rat, Albert began to show fear of the rat by itself, bursting into tears when he saw it. The rat,. then, had become a CS that brought about the CR, fear. Furthermore, the effects of the conditioning lingered: five days later, Albert reacted with fear not only when shown a rat, but when shown objects that looked similar to the white, furry rat, including a white rabbit, a white sealskin coat, and even a white Santa Claus mask. (By the way, we don't know what happened to the unfortunate Little Albert. Watson, the experimenter, has been condemned for using ethically questionable procedures that could never be conducted today.)

Learning by means of classical conditioning also occurs during adulthood. For example, you' may not go to a dentist as often as you should because of prior associations of dentists with pain. On the other hand, classical conditioning also accounts for pleasant experiences. For instance, you may have a particular fond- ness for the smell of a certain perfume or aftershave lotion because the feelings and thoughts of an early love come rushing be\ck whenever you encounter it. Classical conditioning, then, explains many of the reactions we have to stimuli in the world around us.

Emotional responses are especially likely to be learned through classical conditioning processes.

L03 Extinction

Module 15 CLASSICAL CONDITIONING 165

--------------------------------------------------------------------------------------- .... Acquisition (conditioned response and unconditioned response presented together)

Extinction follows (conditioned stimulus alone)

Strong

ureak~ Tr_a_in_in~g C_S_a_lo_ne Pa_u_se S~po_n_ta_n_e_ou_s_r_ec_o_ve_ry~_

e e Time ------------_)0

FIGURE 2 Acquisition, extinction, and spontaneous recovery of a classically conditioned response. A conditioned response (CR)gradually increases in strength during training (A).However, if the conditioned stimulus is presented by itself enough times, the conditioned response gradually fades, and extinction occurs (B). After a pause (C) in which the conditioned stimulus is not presented, spontaneous recovery can occur (D). However, extinction typically reoccurs soon after.

S t Th

1 stimulus), we could produce extinction by repeatedly ringing the bell but not

pon aneous recovery e . .. ... reemergence of an extinguished providing meat. At first the dog would continue to salivate when it heard the conditioned response after a period of bell, but after a few such instances, the amount of salivation would probably rest and with no further conditioning. decline, and the dog would eventually stop responding to the bell altogether.

. At that point, we could say that the response had been extinguished. In sum, extinction occurs when the conditioned stimulus is presented repeatedly with- out the unconditioned stimulus (see Figure 2).

Once a conditioned response has been extin- guished, has it vanished forever? Not necessar- ily. Pavlov discovered this phenomenon when he returned to his dog a few days after the conditioned behavior had seemingly been extinguished. If he rang a bell, the dog once again salivated-an effect known as spontaneous recovery, or the reemer-

. gen~ of an extinguished conditioned response after a period of rest and with no further conditioning.

Spontaneous recovery helps explain why it is so hard to overcome drug addictions. For example, cocaine addicts who are thought to be "cured" can experience an irresistible impulse to use the drug again if they are subsequently confronted by a stimulus with strong connections to the drug, such as a white powder (DrCano & Everitt, 2002; Rodd et al., 2004; Plowright, Simonds, & Butler, 2006). '" )

Once a conditioned response has been extinguished, has it vanished forever?

Not necessarily.

From the perspective Of ... A VETERINARY ASSISTANT How might knowledge of classical conditioning

be useful in your career?

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4 Generalization and Discrimination

STUDY ALERT

Despite differences in color and shape, to most of us a rose is a rose is a rose. The pleasure we experience at the beauty, smell, and grace of the flower is similar for different types of roses. Pavlov noticed a similar phenomenon. His dogs often salivated not only at the ringing of the bell that was used during their original conditioning but at the sound of a buzzer as well.

Such behavior is the result of stimulus gener- alization. Stimulus generalization occurs when a conditioned response follows a stimulus that is similar to the original conditioned stimulus. The greater the similarity between two stimuli, the greater the likelihood of stimulus generalization. Little Albert, who, as we mentioned earlier, was conditioned to be fearful of white rats, grew afraid of other furry white things as well. However, according to the principle of timulus generalization, it is unlikely that he would have been afraid of a

black dog, because its color would have differentiated it sufficiently from the original fear-evoking stimulus.

On the other hand, stimulus discrimination occurs if two stimuli are sufficiently distinct from each other that one evokes a conditioned response but the other does not. Stimulus discrimination provides the ability to dif- ferentiate between stimuli. For example, my dog, Cleo, comes running into the kitchen when she hears the sound of the electric can opener, which she has learned is used to open her dog food when her dinner is about to be served. She does not bound into the kitchen at the sound of the food proces- sor, although it sounds similar'. In other words, she discriminates between the stimuli of can opener and food pro- cessor. Similarly, our ability to discrimi- nate between the behavior of a growling dog and that of one whose tail is wagging can lead to adaptive behavior=-avoiding the growling dog and petting the friendly one.