Psychologists define learning as the process of acquiring new and relatively enduring information or behaviors. By learning, we humans are able to adapt to our environments. We learn to expect and prepare for significant events such as food or pain (classical conditioning). We typically learn to repeat acts that bring rewards and to avoid acts that bring unwanted results (operant conditioning).We learn new behaviors by observing events and by watching others, and through language we learn things we have neither experienced nor observed (cognitive leaming). But how do we learn?
More than 200 years ago, philosophers such as John Locke and David Hume echoed Aristotle's conclusion from 2000 years earlier: We learn by association. Our minds naturally connect events that occur in sequence. Suppose you see and smell freshly baked bread, eat some, and find it satisfying. The next time you see and smell fresh bread, you will expect that eating it will again be satisfying. So, too, with sounds. If you associate a sound with a frightening consequence, hearing the sound alone may trigger your fear. As one 4-year-old exclaimed after watching a TV character get mugged, "If I had heard that music, I wouldn't have gone around the corner!" (Wells, 1981).
Learned associations often operate subtly. Give people a red pen (associated with error marking) rather than a black pen and, when correcting essays, they will spot more errors and give lower grades (Rutchick et a1., 2010). When voting, people are more likely to support taxes to aid education if their assigned voting place is in a school (Berger et a1., 2008) .
Learned associations also feed our habitual behaviors (Wood & Neal, 2007). As we repeat behaviors in a given context - sleeping in a certain posture in bed, walking certain routes from class to class, eating popcorn in a movie theater - the behaviors become associated with the contexts. Our next experience of the context then evokes our habitual response. How long does it take to form such habits? To find out, one British research team asked 96 university students to choose some healthy behavior (such as running before dinner or eating fruit with lunch), to do it daily for 84 days, and to record whether the behavior felt automatic (something they did without thinking and would find it hard not to do). On average, behaviors became habitual after about 66 days (Lally et a1., 2010). (Is there something you'd like to make a routine part of your life? Just do it every day for two months, or a bit longer for exercise, and you likely will find yourself with a new habit.)
Other animals also learn by association. Disturbed by a squirt of water, the sea slug Aplysia protectively withdraws its gill. If the squirts continue, as happens naturally in choppy water, the withdrawal response diminishes. We say the slug habituates. But if the sea slug repeatedly receives an electric shock just after being squirted, its response to the squirt instead grows stronger. The animal has associated the squirt with the impending shock.
Complex animals can learn to associate their own behavior with its outcomes. An aquarium seal will repeat behaviors, such as slapping and barking, that prompt people to toss it a herring.
By linking two events that occur close together, both animals are exhibiting associative learning. The sea slug associates the squirt with an impending shock; the seal associates slapping and barking with a herring treat. Each animal has learned something important to its survival: predicting the immediate future.
This process of learning associations is conditioning, and it takes two main forms:
To simplify, we will explore these two types of associative learning separately. Often, though, they occur together, as on one Japanese cattle ranch, where the clever rancher outfitted his herd with electronic pagers, which he calls from his cell phone. After a week of training, the animals learn to associate two stimuli - the beep on their pager and the arrival of food (classical conditioning). But they also learn to associate their hustling to the food trough with the pleasure of eating (operant conditioning).
Conditioning is not the only form of learning. Through cognitive learning we acquire mental information that guides our behavior. Observational learning, one form of cognitive learning, lets us learn from others' experiences. Chimpanzees, for example, sometimes learn behaviors merely by watching others perform them. If one animal sees another solve a puzzle and gain a food reward, the observer may perform the trick more quickly. So, too, in humans: We look and we learn.
Let's look more closely now at classical conditioning.
For many people, the name Ivan Pavlov (1849-1936) rings a bell. His early twentieth-century experiments-now psychology's most famous research-are classics, and the phenomenon he explored we justly call classical conditioning.
Pavlov's work laid the foundation for many of psychologist John B. Watson's ideas. In searching for laws underlying learning, Watson (1913) urged his colleagues to discard reference to inner thoughts, feelings, and motives. The science of psychology should instead study how organisms respond to stimuli in their environments, said Watson: "Its theoretical goal is the prediction and control of behavior. Introspection forms no essential part of its methods." Simply said, psychology should be an objective science based on observable behavior.
This view, which influenced North American psychology during the first half of the twentieth century, Watson called behaviorism. Pavlov and Watson shared both a disdain for "mentalistic" concepts (such as consciousness) and a belief that the basic laws of learning were the same for all animals-whether dogs or hu mans. Few researchers today propose that psychology should ignore mental processes, but most now agree that classical conditioning is a basic form of learning by which all organisms adapt to their environment.
Pavlov was driven by a lifelong passion for research. After setting aside his initial plan to follow his father into the Russian Orthodox priesthood, Pavlov received a medical degree at age 33 and spent the next two decades studying the digestive system. This work earned him Russia's first Nobel Prize in 1904. But his novel experiments on learning, which consumed the last three decades of his life, earned this feisty scientist his place in history.
Pavlov's new direction came when his creative mind seized on an incidental observation. Without fail, putting food in a dog's mouth caused the animal to salivate. Moreover, the dog began salivating not only at the taste of the food, but also at the mere sight of the food, or at the food dish, or at the person delivering the food, or even at the sound of that person's approaching footsteps. At first, Pavlov considered these "psychic secretions" an annoyance-until he realized they pointed to a simple but important form of learning.
Pavlov and his assistants tried to imagine what the dog was thinking and feeling as it drooled in anticipation of the food. This only led them into fruitless debates. So, to explore the phenomenon more objectively, they experimented. To elinlinate other possible influences, they isolated the dog in a small room, secured it in a harness, and attached a device to divert its saliva to a measuring instrument (FIGURE 26.3). From the next room, they presented food-first by sliding in a food bowl, later by blowing meat powder into the dog's mouth at a precise moment. They then paired various neutral stimuli (NS)-events the dog could see or hear but didn't associate with food-with food in the dog's mouth. If a sight or sound regularly signaled the arrival of food, would the dog learn the link? If so, would it begin salivating in anticipation of the food?
The answers proved to be Yes and Yes. Just before placing food in the dog's mouth to produce salivation, Pavlov sounded a tone. After several pairings of tone and food, the dog, now anticipating the meat powder, began salivating to the tone alone. In later experiments, a buzzer,l a light, a touch on the leg, even the sight of a circle set off the drooling. (This procedure works with people, too. When hungry young Londoners viewed abstract figures before smelling peanut butter or vanilla, their brain soon responded in anticipation to the abstract images alone [Gottfried et al., 2003].)
A dog doesn't learn to salivate in response to food in its mouth. Food in the mouth automatically, unconditionally, triggers a dog's salivary reflex (FIGURE 26.4). Thus, Pavlov called the drooling an unconditioned response (UR) And he called the food an unconditioned stimulus (US).
Salivation in response to the tone, however, is learned. Because it is conditional upon the dog's associating the tone and the food, we call this response the conditioned response (CR). The stimulus that used to be neutral (in this case, a previously meaningless tone that now triggers the salivation) is the conditioned stimulus (CS). Distinguishing these two kinds of stimuli and responses is easy: Conditioned = learned; unconditioned = unlearned.
Let's check your understanding with a second example. An experimenter sounds a tone just before delivering an air puff to your blinking eye. After several repetitions, you blink to the tone alone. What is the NS? The US? The UR? The CS? The CR?2
If Pavlov's demonstration of associative learning was so simple, what did he do for the next three decades? What discoveries did his research factory publish in his 532 papers on salivary conditioning (Windholz, 1997)? He and his associates explored five major conditioning processes: acquisition, extinction, spontaneous recovery, generalization, and discrimination.
To understand the acquisition, or initial learning, of the stimulus-response relationship, Pavlov and his associates had to confront the question of timing: How much time should elapse between presenting the NS (the tone, the light, the touch) and the US (the food)? In most cases, not much-half a second usually works well.
What do you suppose would happen if the food (US) appeared before the tone (NS) rather than after? Would conditioning occur? Not likely. With but a few exceptions, conditioning doesn't happen when the NS follows the US. Remember, classical conditioning is biologically adaptive because it helps humans and other animals prepare for good or bad events. To Pavlov's dogs, the originally neutral tone became a (CS) after signaling an important biological event-the arrival of food (US).To deer in the forest, the snapping of a twig (CS) may signal a predator's approach (US) .If the good or bad event has already occurred, the tone or the sound won't help the animal prepare.
More recent research on male Japanese quail shows how a CS can signal another important biological event (Domjan, 1992, 1994,2005). Just before presenting an approachable female quail, the researchers turned on a red light. Over time, as the red light continued to herald the female's arrival, the light caused the male quail to become excited.
They developed a preference for their cage's red-light district, and when a female appeared, they mated with her more quickly and released more semen and sperm (Matthews et al., 2007). All in all, the quail's capacity for classical conditioning gives it a reproductive edge.
In humans, too, objects, smells, and sights associated with sexual pleasure can become conditioned stimuli for sexual arousal (Byrne, 1982). Onion breath does not usually produce sexual arousal. But when repeatedly paired with a passionate kiss, it can become a CS and do just that (FIGURE 26.5). The larger lesson: Conditioning helps an animal 5uruive and reproduce-by responding to cues that help it gain food, avoid dangers, locate mates, and produce offspring (Hollis, 1997).
Through higher-order conditioning, a new NS can become a new CS. All that's required is for it to become associated with a previously conditioned stimulus. If a tone regularly signals food and produces salivation, then a light that becomes associated with the tone may also begin to trigger salivation. Although this higher-order conditioning (also called second-order conditioning) tends to be weaker than first-order conditioning, it influences our everyday lives. Imagine that something makes us very afraid (perhaps a guard dog associated with a previous dog bite). If something else, such as the sound of a barking dog, brings to mind that guard dog, the bark alone may make us feel a little afraid.
What would happen, Pavlov wondered, if after conditioning, the CS occurred repeatedly without the US? If the tone sounded again and again, but no food appeared, would the tone still trigger salivation? The answer was mixed. The dogs salivated less and less, a reaction known as extinction, the diminished responding that occurs when the CS (tone) no longer signals an impending US (food). But a different picture emerged when Pavlov allowed several hours to elapse before sounding the tone again. After the delay, the dogs would again begin salivating to the tone (FIGURE 26.6). This spontaneous recovery - the reappearance of a (weakened) CR after a pause - suggested to Pavlov that extinction was suppressing the CR rather than eliminating it.
Pavlov and his students noticed that a dog conditioned to the sound of one tone also responded somewhat to the sound of a new and different tone. Likewise, a dog conditioned to salivate when rubbed would also drool a bit when scratched (Windholz, 1989) or when touched on a different body part (FIGURE 26.7). This tendency to respond likewise to stimuli similar to the CS is called generalization.
Generalization can be adaptive, as when toddlers taught to fear moving cars also become afraid of moving trucks and motorcycles, And generalized fears can linger. One Argentine writer who underwent torture still recoils with fear when he sees black shoes - his first glimpse of his torturers as they approached his cell. Generalized anxiety reactions have been demonstrated in laboratory studies comparing abused with nonabused children, When an angry face appears on a computer screen, abused children's brain-wave responses are dramatically stronger and longer lasting (Pollak et aI., 1998).
Stimuli similar to naturally disgusting objects will, by association, also evoke some disgust, as otherwise desirable fudge does when shaped to resemble dog feces (Rozin et aI., 1986). Researchers have also found that we like unfamiliar people more if they look somewhat like someone we've learned to like rather than dislike (Verosky & Todorov, 2010) , (They find this by subtly morphing the facial features of someone we've learned to like or dislike onto a novel face.) In each of these human examples, people's emotional reactions to one stimulus have generalized to similar stimuli.
Pavlov's dogs also learned to respond to the sound of a particular tone and not to other tones. This learned ability to distinguish between a conditioned stimulus (which predicts the US) and other irrelevant stimuli is called discrimination. Being able to recognize differences is adaptive. Slightly different stimuli can be followed by vastly different consequences. Confronted by a guard dog, your heart may race; confronted by a guide dog, it probably will not.
What remains today of Pavlov's ideas? A great deal. Most psychologists now agree that classical conditioning is a basic form of learning. Judged by today's knowledge of the interplay of our biology, psychology, and social-cultural environment, Pavlov's ideas were incomplete. But if we see further than Pavlov did, it is because we stand on his shoulders.
Why does Pavlov's work remain so important? If he had merely taught us that old dogs can learn new tricks, his experiments would long ago have been forgotten. Why should we care that dogs can be conditioned to salivate at the sound of a tone? The importance lies first in this finding: Many other responses to many other stimuli can be classically conditioned in many other organisms - in fact, in every species tested, from earthworms to fish to dogs to monkeys to people (Schwartz, 1984). Thus, classical conditioning is one way that virtually all organism.s learn to adapt to their environment.
Second, Pavlov showed us how a process such as learning can be studied objectively. He was proud that his methods involved virtually no subjective judgments or guesses about what went on in a dog's mind. The salivary response is a behavior measurable in cubic centimeters of saliva. Pavlov's success therefore suggested a scientific model for how the young discipline of psychology might proceed - by isolating the basic building blocks of complex behaviors and studying them with objective laboratory procedures.
Other units in this text - on consciousness, motivation, emotion, health, psychological disorders, and therapy - show how Pavlov's principles can influence human health and wellbeing. Two examples:
Pavlov's work also provided a basis for Watson's (1913) idea that human emotions and behaviors, though biologically influenced, are mainly a bundle of conditioned responses. Working with an ll-month-old, Watson and Rosalie Rayner (1920; Harris, 1979) showed how specific fears might be conditioned. Like most infants, "Little Albert" feared loud noises but not white rats. Watson and Rayner presented a white rat and, as Little Albert reached to touch it, stmck a hammer against a steel bar just behind his head. After seven repeats of seeing the rat and hearing the frightening noise, Albert burst into tears at the mere sight of the rat. Five days later, he had generalized this startled fear reaction to the sight of a rabbit, a dog, and a sealskin coat, but not to dissimilar objects, such as toys.
For years, people wondered what became of Little Albert. Not until 2009 did some psychologist-sleuths identify him as Douglas Merritte, the son of a campus hospital wet nurse who received $1 for her tot's participation. Sadly, Albert died at age 6, apparently having suffered all his short life from congenital hydrocephalus, complicated later by meningitis. This brain damage probably influenced his behavior during Watson and Rayner's experiment (Beck et aI., 2009, 2010; Fridlund et al., 2012a,b). People also wondered what became of Watson. After losing his Johns Hopkins professorship over an affair with Rayner (whom he later married), he joined an advertising agency as the company's resident psychologist. There he used his knowledge of associative learning to conceive many successful advertising campaigns, including one for Maxwell House that helped make the"coffee break" an American custom (Hunt, 1993).
The treatment of Little Albert would be unacceptable by today's ethical standards. Also, some psychologists, noting that the infant's fear wasn't learned quickly, had difficulty repeating Watson and Rayner's findings with other children. Nevertheless, Little Albert's learned fears led many psychologists to wonder whether each of us might be a walking repository of conditioned emotions. If so, might extinction procedures or even new conditioning help us change our unwanted responses to emotion-arousing stimuli? One patient, who for 30 years had feared going into an elevator alone, did just that. Following his therapist's advice, he forced himself to enter 20 elevators a day. Within 10 days, his fear had nea rly vanished (Ellis & Becker, 1982). With support from AirTran, comedian-writer Mark Malkoff likewise extinguished his fear of flying. He lived on an airplane for 30 days, taking 135 flights that had hin, in the air 14 hours a day (NPR, 2009). After a week and a half, his fears had faded and he began playing games with fellow passengers. (His favorite antic was the "toilet paper experiment": He'd put one end of a roll in the toilet, unroll the rest down the aisle, and flush. The entire roll would be sucked down in three seconds.) In Units XII and XIII we will see more examples of how psychologists use behavioral techniques to treat emotional disorders and promote personal growth.
