Chapter 6Learning

©2013 W. W. Norton & Company, Inc.

Gazzaniga • Heatherton • Halpern

FOURTH EDITION

Psychological Science

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Learning

• B. F. Skinner, who was inspired by the work of Watson and Pavlov, has been one of the most influential people in contemporary psychology

• Skinner believed that, to be scientists, psychologists had to study observable actions and focus on the behaviors people and nonhuman animals display

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6.1 What Ideas Guide the Study of Learning?

• Define classical conditioning.• Differentiate between US, UR, CS, and CR.• Describe the role of learning in the

development and treatment of phobias and drug addiction.

• Discuss the evolutionary significance of classical conditioning.

• Describe the Rescorla-Wagner model of classical conditioning.

6.1 What Ideas Guide the Study of Learning?

• Skinner and other behaviorists dismissed the importance of introspection and mental states in favor of basic learning principles and scientific approaches to psychology.

• Learning theories have been used to improve quality of life and to train humans and nonhuman animals to learn new tasks.

Learning Results from Experience

• Learning: a relatively enduring change in behavior, resulting from experience

• Associations develop through conditioning, a process in which environmental stimuli and behavioral responses become connected– classical (Pavlovian) conditioning: learning that

two types of events occur together

– operant (instrumental) conditioning: learning that a behavior leads to a particular outcome

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Learning Results from Experience

• Learning Theory arose in the early twentieth century in response to Freudian and introspective approaches

• John B. Watson argued that only observable behavior was a valid indicator of psychological activity, and that the infant mind was a tabula rasa, or blank slate

• He stated that the environment and its effects were the sole determinants of learning

• Behaviorism was the dominant paradigm into the 1960s, and had a huge influence on every area of psychology

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Behavioral Responses Are Conditioned

• Watson was influenced by Ivan Pavlov’s research on the salivary reflex, an automatic response when food stimulus is presented to a hungry animal

• Pavlov noticed the dogs salivated as soon as they saw the bowls that usually contained food, suggesting a learnedresponse

• Twitmyer made a similar observation of the knee-jerk reflex in humans: when paired with a bell, subjects can be conditioned to demonstrate the knee-jerk response without other triggers

Pavlov’s Experiments

• Classical (Pavlovian) conditioning: A neutral object comes to elicit a response when it is associated with a stimulus that already produces that response

• A typical Pavlovian experiment involves:– Conditioning trials: neutral stimulus AND unconditioned

stimulus are paired to produce reflex, e.g. salivation• Neutral stimulus: anything the animal can see or hear as long as it

is NOT associated with the reflex being tested, e.g. ringing bell

• Unconditioned stimulus (US): a stimulus that elicits a response, such as a reflex, without any prior learning, e.g. food

– Critical trials: neutral stimulus alone is tested, and effect on the reflex is measured

Terminology of Pavlov’s Experiments

• Unconditioned response (UR): a response that does not have to be learned, such as a reflex

• Unconditioned stimulus (US): a stimulus that elicits a response, such as a reflex, without any prior learning

• Conditioned stimulus (CS): a stimulus that elicits a response only after learning has taken place

• Conditioned response (CR): a response to a conditioned stimulus; a response that has been learned

Can you think of any learned associations that have classically conditioned you?

Acquisition, Extinction, and Spontaneous Recovery

• Pavlov was influenced by Darwinand believed that conditioning is the basis of adaptive behaviors

• Acquisition: the gradual formation of an association between the CS and US

• The critical element in the acquisition of a learned association is time, or contiguity

• The CR is stronger when there is a very brief delay between the CS and the US– For example, scary music begins to play right before a

frightening scene in a movie—not during or after

Acquisition, Extinction, and Spontaneous Recovery

• How long do learned behaviors persist?• Animals must learn when associations are no longer

adaptive– extinction: a form of learning that the prior association no

longer holds. The CR is weakened when the CS is repeated without the US, and eventually extinguishes

• Spontaneous recovery: a previously extinguished response reemerges after the presentation of the CS

• The recovery will fade unless the CS is again paired with the US

• Extinction inhibits the associative bond, but does not eliminate it

Generalization, Discrimination, and Second Order Conditioning

• In a learning situation, how does the brain determine which stimulus is relevant?

• stimulus generalization: responding to stimuli that are similar but not identical to the CS produce the CR

• stimulus discrimination: a differentiation between two similar stimuli when only one of them is consistently associated with the US

• Second-order conditioning: a CS becomes associated with other stimuli associated with the US. This phenomenon helps account for the complexity of learned associations

Phobias and Addictions Have Learned Components

• Classical conditioning helps explain many behavioral phenomena. Among the examples are phobias and addictions.

Phobias and Their Treatment

• Phobia: an acquired fear out of proportion to the real threat of an object or of a situation

• Fear conditioning: the process of classically conditioning animals to fear neutral objects

• The responses include specific physiological and behavioral reactions– freezing: may be a hardwired response to fear that

helps animals deal with predators

Phobias and their Treatment

• In 1919, John B. Watson became one of the first researchers to demonstrate the role of classical conditioning in the development of phobias by devising the “Little Albert” experiment

• At the time, the prominent theory of phobias wasbased on Freudian ideas about unconscious repressed sexual desires

• Watson proposed that phobias could be explained by simple learning principles, such as classical conditioning

Phobias and their Treatment

• The “Little Albert” Research Method:– Little Albert was presented with neutral objects (a white

rat and costume masks) that provoked a neutral response

– During conditioning trials, when Albert reached for the white rat (CS) a loud clanging sound (US) scared him (UR)

– Results: Eventually, the pairing of the rat (CS) and the clanging sound (US) led to the rat’s producing fear (CR) on its own. The fear response generalized to other stimuli presented with the rat initially, such as the costume masks

– Conclusion: Classical conditioning can cause people to fear neutral objects

Phobias and their Treatment

• Watson planned to conduct extinction trials to remove the learned phobias but Albert’s mother removed him from the study– Do you think this type of research is ethical?

• Watson’s colleague, Mary Cover Jones, used classic conditioning techniques to develop effective behavioral therapies to treat phobias– Counterconditioning –exposing a patient to small doses of

the feared stimulus while they engage in an enjoyable task

Phobias and their Treatment

• Systematic desensitization:a formal treatment based on counterconditioning– Developed by behavioral therapist Joseph Wolpe

in 1997

– CS → CR1 (fear) connection can be broken by developing a CS → CR2 (relaxation) connection

• Psychologists now believe that exposure to the feared stimulus is more important than relaxation

Drug Addiction

• Classical conditioning also plays an important role in drug addiction.

• Environmental cues associated with drug use can induce conditioned cravings

• Unsatisfied cravings may result in withdrawal, an unpleasant state of tension and anxiety, coupled with changes in heart rate and blood pressure

• The sight of drug cues leads to activation of the prefrontal cortex and various regions of the limbic system and produces an expectation that the drug high will follow

Drug Addiction

• Psychologist Shepard Siegel (2005) believed exposing addicts to drug cues was an important part of treating addiction – Exposure helps extinguish responses to the cues and prevents them

from triggering cravings

• Siegel and his colleagues conducted research into the relationship between drug tolerance and situation– The body has learned to expect the drug in that location and

compensates by altering neurochemistry or physiology to metabolize it

– Conversely, if addicts take their usual large doses in novel settings, they are more likely to overdose because their bodies will not respond sufficiently to compensate

Classical ConditioningInvolves More Than Events Occurring at the Same Time

• Pavlov’s original explanation for classical conditioning was that any two events presented in contiguity would produce a learned association

• Pavlov and his followers believed that the association’s strength was determined by factors such as the intensity of the conditioned and unconditioned stimuli

• However, in the mid-1960s, a number of challenges to Pavlov’s theory suggested that some conditioned stimuli were more likely than others to produce learning

• Contiguity was not sufficient to create CS-US associations

Evolutionary Significance

• Psychologist John Garcia and colleagues showed that certain pairings of stimuli are more likely to become associated than others

• conditioned food aversion:the association between eating a food and getting sick– Response occurs even if the illness was caused by a virus or some

other condition

– Especially likely to occur if the food was not part of the person’s usual diet. A food aversion can be formed in one trial

• Animals that associate a certain flavor with illness, and therefore avoid that flavor, are more likely to survive and pass along their genes

Evolutionary Significance

• Learned adaptive responses may reflect the survival value that different auditory and visual stimuli have based on potential dangers associated with the stimuli

• What evolutionary value do you see in this learned behavior?

• Biological preparedness: Psychologist Martin Seligman (1970) argued that animals are genetically programmed to fear specific objects

• People are predisposed to wariness of outgroup members (Olsson, Ebert, Banaji, & Phelps, 2005)

Learning Involves Cognition

• Classical conditioning is a way that animals come to predict the occurrence of events—which prompted psychologists to take a cognitive perspective on learning

• Robert Rescorla argued that for learning to take place, the conditioned stimulus must accurately predict the unconditioned stimulus

• Rescorla-Wagner model: states that the strength of the CS-US association is determined by the extent to which the unconditioned stimulus is unexpected or surprising

Learning Involves Cognition

• Other aspects of classical conditioning consistent with the Rescorla-Wagner model:– Orienting response: occurs when an animal

encounters a novel stimulus

– Blocking effect: once a conditioned stimulus is learned, it can prevent the acquisition of a new conditioned stimulus

– Occasion setter: a stimulus associated with a CS that acts as a trigger for the CS

Critical Thinking Skill: Avoiding the Association of Events

with Other Events That Occur at the Same Time

• People, and apparently other animals, have a strong need to understand what causes or predicts events. Their resulting associations can lead people to cling to superstitions

• What misfortunes could actually occur in the situations shown on the following slide?

6.2 How Does Operant Conditioning Differ from Classical Conditioning?

• Define operant conditioning.• Distinguish between positive reinforcement,

negative reinforcement, positive punishment, and negative punishment.

• Distinguish between schedules of reinforcement.

• Identify biological and cognitive factors that influence operant conditioning.

6.2 How Does Operant Conditioning Differ from Classical Conditioning?

• Operant (instrumental) conditioning: a learning process in which the consequences of an action determine the likelihood that it will be performed in the future

• B. F. Skinner chose the term operant to express the idea that animals operate on their environments to produce effects.

• Edward Thorndike performed the first reported carefully controlled experiments in comparative animal psychology using a puzzle box.– Law of Effect: Any behavior that leads to a “satisfying state of affairs”

is likely to occur again, and any behavior that leads to an “annoying state of affairs” is less likely to occur again.

Reinforcement Increases Behavior

• Thirty years after Thorndike, Skinner developed a more formal learning theory based on the law of effect

• He objected to the subjective aspects of Thorndike’s law of effect: States of “satisfaction” are not observable empirically

• Skinner believed that behavior occurs because it has been reinforced– reinforcer: a stimulus that follows a response and

increases the likelihood that the response will be repeated

The Skinner Box

• An operant chamber that allowed repeated conditioning trials without requiring interaction from the experimenter

• Contained one lever connected to a food supply and another connected to a water supply

Shaping

• Sometimes animals take a long time to perform the precise desired action. What can be done?

• Shaping: an operant-conditioning technique that consists of reinforcing behaviors that are increasingly similar to the desired behavior– successive approximations: anybehavior that even slightly

resembles the desired behavior

• Suppose you wanted to teach yourself to do something. Which behavior would you choose, and how would you go about shaping it?

Reinforcers Can Be Conditioned

• primary reinforcers: satisfy biological needs such as food or water

• secondary reinforcers: events or objects established through classical conditioning that serve as reinforcers but do not satisfy biological needs, e.g. money or compliments

Reinforcer Potency

• David Premack theorized about how a reinforcer’s value could be determined

• The key is the amount of time an organism, when free to do anything, engages in a specific behavior associated with the reinforcer

• Premack principle: Using a more valued activity can reinforce the performance of a less valued activity– How do you think you could use this principle on yourself?

Both Reinforcement and Punishment Can Be Positive or Negative

• Reinforcement and punishment have the opposite effects on behavior– Reinforcement increases a behavior’s probability

– Punishment decreases its probability

• Both reinforcement and punishment can be positive or negative

• This designation depends on whether something is given or removed, not on whether any part of the process is good or bad

Positive and Negative Reinforcement

• Reinforcement — positive or negative — increases the likelihood of a behavior– positive reinforcement: the administration of a

stimulus to increase the probability of a behavior’s being repeated, e.g. a reward

– negative reinforcement: the removal of a stimulus to increase the probability of a behavior’s being repeated, e.g. requiring a rat to press a lever to turn off a shock

Positive and Negative Punishment

• Punishment reduces the probability that a behavior will recur– positive punishment: the administration of a

stimulus to decrease the probability of a behavior’s recurring, e.g. receiving a ticket for speeding

– negative punishment: the removal of a stimulus to decrease the probability of a behavior’s recurring, e.g. taking away driving privileges for bad behavior

Effectiveness of Parental Punishment

• For punishment to be effective, it must be reasonable, unpleasant, and applied immediately so that the relationship between the unwanted behavior and the punishment is clear– How might this go wrong?

• Punishment often fails to offset the reinforcing aspects of the undesired behavior

• Research indicates that physical punishment is often ineffective, compared with grounding and time-outs

• Many psychologists believe that positive reinforcement is the most effective way of increasing desired behaviors while encouraging positive parent/child bonding

Operant Conditioning is Influenced by Schedules of Reinforcement

• How often should reinforcers be given?• continuous reinforcement: a type of learning

in which behavior is reinforced each time it occurs

• partial reinforcement: a type of learning inwhich behavior is reinforced intermittently

• Partial reinforcement’s effect on conditioning depends on the reinforcement schedule

Ratio and Interval Schedules

• Partial reinforcement can be administered according to either the number of behavioral responses or the passage of time– ratio schedule: Reinforcement is based on the

number of times the behavior occurs

– interval schedule: Reinforcement is provided after a specific unit of time

• Ratio reinforcement generally leads to greater responding than does interval reinforcement

Fixed and Variable Schedules

• Partial reinforcement can also be given on a fixed schedule or a variable schedule– fixed schedule: Reinforcement is provided after a

specific number of occurrences or after a specific amount of time

– variable schedule: Reinforcement is provided at different rates or at different times

Behavioral Persistence

• Continuous reinforcement is highly effective for teaching a behavior. If the reinforcement is stopped, however, the behavior extinguishes quickly

• variable-ratio schedule: persistent behavior thatonly sometimesresults in reward

• partial-reinforcement extinction effect: Behavior is more persistent under partial reinforcement than under continuous reinforcement– Can this explain why gambling is so addictive?

Psychology: Knowledge You Can Use—Can Behavior Modification Help Me

Stick with an Exercise Program? • Consider these steps:– Identify a behavior you wish to change– Set goals– Monitor your behavior– Select a reinforcer and decide on a reinforcement

schedule– Reinforce the desired behavior– Modify your goals, reinforcements, or

reinforcement schedules, as needed

Behavior Modification

• Behavior modification: the use of operant-conditioning techniques to eliminate unwanted behaviors and replace them withdesirable ones

• Token economies operate on the principle of secondary reinforcement. Tokens are earned for completing tasks and lost for bad behavior. Tokens can later be traded for objects or privileges

Biology and Cognition Influence Operant Conditioning

• Behaviorists such as Skinner believed that all behavior could be explained by straightforward conditioning principles

• However, a great deal about behavior remains unexplained

• Biology constrains learning, and reinforcement does not always have to be present for learning to take place

Biological Constraints

• Animals have a hard time learning behaviors that run counter to their evolutionary adaptation

• Marian and Keller Breland used operant-conditioning techniques to train animals but ran into difficulty when the tasks were incompatible with innate adaptive behaviors

• Conditioning is most effective when the association between the response and the reinforcement is similar to the animal’s built-in predispositions– For example, Bolles argued that animals have built-in

defense reactions to threatening stimuli

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Acquisition/Performance Distinction

• Tolman argued that learning can take place without reinforcement– latent learning: takes place in the absence of reinforcement

– insight learning: A solution suddenly emerges after either a period of inaction or of contemplation

• Tolman’s studies involved rats running through mazes– cognitive map: a visual/spatial mental representation of an

environment

• The presence of reinforcement does not adequately explain insight learning, but it helps determine whether the behavior is subsequently repeated

6.3 Does Watching Others Affect Learning?

• Describe the concept of the meme.• Define observational learning.• Generate examples of observational learning,

modeling, and vicarious learning.• Discuss contemporary evidence regarding the

role of mirror neurons in learning.

6.3 Does Watching Others Affect Learning?

• Teaching someone to perform a complex task requires more than reinforcing arbitrary correct behaviors.

• We learn many behaviors, including attitudes, through observation.

Learning Can Be Passed On through Cultural Transmission

• Meme: a unit of knowledge transmitted within a culture

• Memes can be conditioned through association or reinforcement, but are often learned by watching the behavior of other people

• Through social learning, some behaviors are passed along from one generation to the next

Learning Can Occur through Observation and Imitation

• Observational learning: the acquisition or modification of a behavior after exposure to at least one performance of that behavior

• Observational learning is a powerful adaptive tool for humans and other animals– Can you think of some examples of observational

learning in animals?

Bandura’s Observational Studies

• Bandura’s studies suggest that exposing children to violence may encourage them to act aggressively

Media and Violence

• The extent to which media violence impacts aggressive behavior in children is debated

• Some studies demonstrate desensitization to violence after exposure to violent video games

• However, it is difficult to draw the line between “playful” and “aggressive” behaviors in children

• There may be extraneous variables that affect both TV habits AND violent tendencies

• Based on what you have just learned, how might media impact behavior?

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Social Learning of Fear

• Susan Mineka noticed that lab-reared monkeys were not afraid of snakes the way monkeys in the wild are

• Her research demonstrated that animals’ fears can be learned through observation

• Social forces play a role in fear-learning in humans too

Demonstration and Imitation

• modeling: the imitation of behavior through observational learning

• Modeling is effective only if the observer is physically capable of imitating the behavior

• Imitation is much less common in nonhuman animals than in humans

• Adolescents who associate smoking with admirable figures are more likely to begin smoking

Vicarious Reinforcement

• vicarious learning: learning the consequences of an action by watching others being rewarded or punished for performing the action

• A key distinction in learning is between the acquisition of a behavior and its performance

• In other words, learning a behavior does not necessarily lead to performing that behavior

Mirror Neurons

• What happens in the brain during imitation learning?

• mirror neurons: neurons that are activated when one observes another individual engaging in an action and when one performs the action that was observed

• May serve as the basis of imitation learning, but the firing of mirror neurons does not always lead to imitative behavior

• May be the neural basis for empathy and play a role in humans’ ability to communicate through language

• Debatable if brain activity reflects prior learning rather than imitation

6.4 What Is the Biological Basis of Learning?

• Discuss the role of dopamine and the nucleus accumbens in the experience of reinforcement.

• Define habituation, sensitization, and long-term potentiation.

• Describe the neural basis of habituation, sensitization, long-term potentiation, and fear conditioning.

6.4 What Is the Biological Basis of Learning?

• When animals and people learn, what changes in the brain?

• Researchers are rapidly identifying the neurophysiological basis of learning.

• Similar brain activity occurs for most rewarding experiences.

Dopamine Activity Underlies Reinforcement

• Positive reinforcement works in two ways:– provides the subjective experience of pleasure

– increases wanting for the object or event that produced the reward

• The neurotransmitter dopamine is involved in addictive behavior and plays an important role in reinforcement

Pleasure Centers

• intracranial self-stimulation: self-administered shock to pleasure centers of the brain

• Starving rats prefer ICSS to food over 80 percent of the time

• The neural mechanisms underlying both ICSS and natural reward appear to use the same neurotransmitter: dopamine

• This suggests dopamine serves as the neurochemical basis of positive reinforcement in operant conditioning

• Interfering with dopamine eliminates self-stimulation as well as naturally motivated behaviors

Dopamine and Reward• The nucleus accumbens is a subcortical brain region that is part of the

limbic system• More dopamine is released under deprived conditions than under

nondeprivedconditions– Do you have the intuition that food tastes better when you are

hungry?• In operant conditioning, dopamine release sets the value of a reinforcer,

and blocking dopamine decreases reinforcement– Dopamine blockers are can also help people with Tourette’s

syndrome regulate their involuntary body movements• Robinson and Berridge (1993) introduced an important distinction

between the wanting and liking aspects of reward– For example, a smoker may want a cigarette but not especially

enjoy it• Dopamine appears to be especially important in wanting a reward

Secondary Reinforcers Also Rely on Dopamine

• Natural reinforcers appear to signal dopamine reward directly

• Secondary reinforcers at first fail to trigger dopamine release but may do so readily after they are paired with unconditioned stimuli

• Money is a secondary reinforcer that activates dopamine systems

Habituation and Sensitization Are Simple Models of Learning

• Kandel’s work on the aplysia has shown that habituation and sensitization, two simple forms of learning, occur through alteration in neurotransmitter release– habituation: a decrease in behavioral response

after repeated exposure to a nonthreatening stimulus

– sensitization: an increase in behavioral response after exposure to a threatening stimulus

Long Term Potential Is a Candidate for the Neural Basis of Learning

• long-term potentiation (LTP): the strengthening of a synaptic connection, making the postsynaptic neurons more easily activated

• Through LTP, intense stimulation of neurons strengthens synapses, increasing the likelihood that one neuron’s activation will increase the firing of other neurons

• LTP effects are most easily observed in brain sites known to be involved in learning and memory, such as the hippocampus

• Research has also supported Hebb’s rule that neurons that fire together wire together

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LTP and the NMDA Receptor

• LTP occurs when NMDA receptors are stimulated by nearby neurons

• Joseph Tsien modified genes in mice to make the genes’ NMDA receptors more efficient

• Tsein’s “Doogie Mice” learned novel tasks quicker and showed increased fear conditioning

Fear Conditioning

• LTP in the amygdala appears to play a role in fear conditioning

• Joseph LeDoux’s research suggests that fear conditioning might produce long-lasting learning through the induction of LTP

• Heightened activity in the amygdala, when subjects watched another person’s distress, suggests that similar mechanisms are involved in conditioned and observational fear learning

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