Mazur Chapter 3: Basic Principles of Classical Conditioning Flashcards Preview

PSYCH 3011 > Mazur Chapter 3: Basic Principles of Classical Conditioning > Flashcards

Flashcards in Mazur Chapter 3: Basic Principles of Classical Conditioning Deck (39)
Loading flashcards...

Basic Terminology


To conduct a typical experiment in classical conditioning, an experimenter first selects some stimulus that reliably elicits a characteristic response

The stimulus of this pair is called the unconditioned stimulus (US), and the response called the unconditioned response (UR)

The term unconditioned is used to signify that the connection between the stimulus and response is unlearned (innate)

In Pavlov’s experiment, the US was the presence of food in the dog’s mouth, and the UR was the secretion of saliva

The third element of the classical conditioning paradigm is the conditioned stimulus (CS), which can be any stimulus that does not initially evoke the UR

In Pavlov’s experiment, the CS was a bell

The term conditioned stimulus indicates that is only after conditioning has taken place that the bell will elicit the response of salivation

Any salivation that occurs during the CS but before the US is referred to as a conditioned response (CR), since it is only because of the conditioning procedure that the bell now elicits salivation

The two components of the initial stimulus-response pair are the US and the UR

Through the procedures of classical conditioning, a novel stimulus, the CS, begins to elicit responses of its own, and these responses to the CS are called CRs since they are learned, or conditioned, responses

Much of the research on classical conditioning has been conducted with a small number of conditioning preparations – conditioning situations using a particular US, UR, and species of subject
o E.g. eyeblink conditioning, condition suppression, skin conductance response


Eyeblink Conditioning


Conditioning of the eyeblink reflex has been studied with humans, rabbits, rats and other animals

The US is a puff of air directed at the eye, and the UR is the eyeblink

The CS may be a light, tone or some tactile stimulus such as a vibrational experimental chamber, and the duration of the CS is typically about one second

Like the UR, the CR is an eyeblink, but its form may be different (smaller and more gradual blink)

Eyeblink conditioning often requires a large number of CS-US pairings


Conditioned Suppresion

aka “Conditioned Emotional Response” (CER)


Subjects are usually rats

The US is an aversive event such as a brief electric shock delivered to the metal bars that form the floor of the experimental chamber

The UR to shock may include several different behaviors

The measure of conditioning in this situation is the suppression of ongoing behavior when the CS (which signals that a shock is forthcoming) is presented

The duration of the CS is generally much longer in the conditioned suppression procedure – one minute or more is typical

The shock comes at the end of the of 1-minute CS and lasts about 1 second

**Conditioning takes place in far fewer trials than in the eyeblink procedure, perhaps partly because the shock is more intense than air puffs


The Skin Conduction Response (SCR)

a.k.a. electrodermal response, a.k.a. galvanic skin response


Subjects are usually human

The SCR is a change in the electrical conductivity of the skin

To measure a person’s SCR, two coin-shaped electrodes are attached the palm, and electrodes are connected to a device that measures momentary fluctuations in the conductivity of the skin caused by small changes in perspiration

The conductivity of the skin is altered by emotions such as fear or surprise

Electric shock is a stimulus that reliably produces a large increase in skin conductivity

A similar increase in conductivity can be conditioned to any CS that is paired with shock


Taste-Aversion Learning


Subjects are usually rats

CS is the taste of something the subject eats or drinks

After eating or drinking the animals given an injection of a poison (the US) that makes it ill

Several days later, after the animal has fully recovered from its illness, it is again given the opportunity to consume the substance that served as the CS

The usual result is that the animal consumes little or none of this food

Thus, the measure of conditioning is the degree to which the animal avoids the food

Some psychologists have suggested that taste-aversion learning is not an ordinary example of classical conditioning, but that it violates some of the general principles that apply to classical conditioning

Taste-aversion often develops after just one conditioning trial and this rapidity of conditioning is advantageous for certain theoretical questions

Taste aversion is something that many people experience at least once in their lives

An aversion may develop even if the individual is certain that the food was not the cause of the subsequent illness


Pavlov’s Stimulus Substitution Theory


Through repeated pairings between CS and US, the CS becomes a substitute for the US, so that the response initially elicited only by the US is now also elicited by the CS

Today, very few conditioning researchers believe the theory to be correct

The CR is almost never an exact replica of the UR

Not all parts of the UR to a stimulus become part of the CR
• e.g., a well-trained CS such as a bell will elicit salivation, but it will generally not elicit the chewing and swallowing responses

A CR may include some response that are not part of the UR
• e.g., sometimes a dog moves its entire body closer to the ringing bell

The CR is someitmes opposite in direction to the UR
• e.g. decreased heartrates of guinea pigs to a CS paired with a shock

In order to amend this theory, it should be acknowledged that only some components of the UR are transferred to the CR

Some components of the UR may depend on the physical characteristics of the US, and they will not be transferred to a CS with very different physical characteristics

Also, A CS such as a bell frequently elicits URs of its own, and these may become part of the CR
• e.g., when the dog hears the bell, and may exhibit an orienting response

In short, the form of the CR may reflect both the UR to the US (e.g. salivation, but not chewing or swallowing) and the UR to the CS itself (e.g. orienting toward the sound of the bell)

Possibly the strongest argument against stimulus substitution theory arises from the finding that in some cases the direction of the CR is opposite to that of the UR

Conditioned responses that are the opposite of the UR are called conditioned compensatory responses

For all these reasons, it is often difficult to predict in advance what the CR will look like in a specific instance – it may resemble the UR, or it may be very different


sign-tracking theory


Animals tend to orient themselves toward, approach, and explore any stimuli that are good predictors of important events, such as the delivery of food


conditioned compensatory responses


Conditioned responses that are the opposite of the UR


Pavlov’s “Centers” of the brain


Pavlov proposed that there are specific parts of the brain that become active whenever a US is presented – the “US center” of the brain

Similarly, for every different CS, there is a separate “CS center”, which becomes active whenever that particular CS is presented

Pavlov also assumed that for every UR there is part of the brain that can be called a “response center”, and it is the activation of this response center that initiates the neural commands that ultimately produce the observed response

Since the US elicits the UR without any prior training, Pavlov assumed that there is an innate connection between the US center and the response center


S-S vs S-R


Pavlov proposed that somehow an association develops during the course of classical conditioning, so that now the CS produces activity in the response center, and the CR is observed

There are at least two types of new associations that would give the CS the capacity to elicit a CR

S-R association—direct association between the CS center and the response center is formed during conditioning (stimulus and response “S-R”)

S-S association—a direct association between the CS center and the US center is formed during conditioning (CS-US)

Later, when the CS is presented, the CS center is activated, which activates the US center through the newly formed association, which in turn activates the response center

Pavlov tended to favor the S-S position


Attempts to study S-R vs S-S connections


Rescorla (1973) used the following reasoning: If the S-S position is correct, then after conditioning, the occurrence of a CR depends on the continued strength of two associations:

  1. The learned association between the CS center and the US center
  2. The innate association between the US Center and the response center

If the US-response connection is somehow weakened, then this should reduce the strength of the CR, since the occurrence of the CR depends on this connection

If the S-R position is correct, however, the strength of the CR does not depend on the continued integrity of the US-response association, but only on the direct association between the CS center and the response center

Rescorla used the condition suppression procedure with rats

A conditioned suppression of lever pressing would develop in response to any CS paired with the noise

But the noise was also susceptible to habituation if it was repeatedly presented

Two groups of rats were classically conditioned in an identical matter with a light as the CS and the noise as the US

In phase 2, the habituation group received many presentations of the noise by itself, in order to habituate the rats’ fear of the noise
• [The Control group received no stimuli]

This technique of decreasing the effectiveness of the US after excitatory CS has been created is called US devaluation

He found high levels of suppression to the light in the control group, but significantly lower levels of suppression in the habituation group

He concluded that the strength of the CR depends on the continued strength of the US-response association, as predicted by the S-S position, but not the S-R position


US devaluation


Technique of decreasing the effectiveness of the US after excitatory CS has been created

e.g. Habituating rats to loud noise after light has been paired, light CS+ loses excitatory strength




The part of a conditioning experiment in which the subject first experiences a series of CS-US pairings, and during which the CR gradually appears and increases in strength is called the acquisition phase

Strong USs also usually result in faster conditioning

This is also true of the intensity of the CS (e.g. loud tone, bright light)




THe maximum level of conditioned responding that is gradually approached as conditioning proceeds

The size or intensity of the US has a major influence on the asymptote of conditioning




Technique for producing the reduction and eventual disappearance of the CR

[The passage of time has relatively little effect on the strength of a CR]

Extinction involves repeatedly presenting the CS without the US

Though extinction results in elimination of the CR, it does not simply reverse the effects of the previous acquisition phase

At least three different phenomena show that whatever association was formed during acquisition is not erased during extinction:

Spontaneous recovery
Rapid reacquisition

In summation, extinction can cause a CR to disappear, and after repeated extinction sessions spontaneous recovery may disappear, but the subject will never be exactly the same as before the conditioning began


Spontaneous Recovery


After extinction produces no CR’s, often the next day a reappearance of CRs occurs, which Pavlov treated as proof that CS-US association is not permanently destroyed in an extinction procedure

If extinction serves to undo or erase learning that occurred in acquisition, why would CRs spontaneously reappear for the conditioning trials?

If more time elapsed between the first and second extension sessions, more spontaneous recovery is observed


Inhibition Theory


After extinction is complete, the subject is left with two counteracting associations

  1. CS-US association formed during acquisition is called an excitatory association because through this association the CS now excites, or activates the US center
  2. A parallel but inhibitory association develops during extinction

When extinction is complete, the effects of the excitatory and inhibitory associations cancel out, so that the US center is no longer activated by the presentation of the CS

The inhibitory CS-US association is strong enough to counteract the excitatory association completely, so that no CRs are observed

However, Pavlov proposed that inhibitory associations are more fragile than excitatory associations, and they are more severely weakened by the passage of time

Therefore, the reappearance of CRs are observed due to the weakened inhibitory association no longer fully able to counteract the excitatory association

Further extinction trials strengthen the inhibitory association, and CRs once again disappear

The amount of spontaneous recovery becomes smaller and smaller until it no longer occurs

According to the inhibition theory, this happens because the inhibitory association becomes progressively stronger with repeated extinction sessions

Other theories of spontaneous recovery
*The organism simply stops processing or paying attention to the CS
o When returned to the conditioning chamber, the attention to the CS is revived leading to spontaneous recovery of CRs

*The CS becomes an ambiguous stimulus because it has been associated both the US and then with the absence of the US
o The ambiguity relies on context for meaning, and the presence of a buzzer, for example, may serve to reduce confusion




The presentation of a distracting stimulus disrupts the fragile inhibition that supposedly develops during extinction
• e.g., a CS (bell) no longer evokes any salivation → a novel stimulus such as a buzzer is presented a few seconds before the bell → the bell may once again elicit a CR of salivation

According to the inhibition theory, the more stable excitatory association is less affected by the distracting stimulus than is the inhibitory association, and the result is a reappearance of the CR


Rapid Reacquisition


Similar to Ebbinghaus’ “savings”

If a subject receives an acquisition phase, and extinction phase, and then another acquisition phase with the same CS in the same US, the rate of learning is substantially faster in the second acquisition phase → the reacquisition phase


Conditioned Inhibition


If it can be shown that a CS prevents the occurrence of a CR, or that it reduces the size of the CR from what it would otherwise be, then this CS is called an inhibitory CS or a conditioned inhibitor (CS-)

e.g. – using two different CSs, a buzzer and the light
o In the first phase, the buzzer is paired with food until the dog salivates at the sound of the buzzer
o The buzzer can now be called an excitatory CS (CS+) because it regularly elicits a CR
o In the second phase, the dog received two types of trials, some are exactly like the first, and some trials have both the buzzer and the light presented simultaneously, but no food is delivered
o The simultaneous presentation of two or more CSs like these is called a compound CS
o At first, compound CS may elicit the CR

As phase 2 continues, however, the dog will eventually salivate on trials of the buzzer alone, but not on trials with both the buzzer and the light

If the light is truly a conditioned inhibitor, it should have the capacity to reduce the salvation produced by any CS, not just by the buzzer with which it was originally presented

Summation: A stimulus will become a conditioned inhibitor if it reliably signals the absence of the US in a context where the US would otherwise be expected to occur
o e.g. Because the light signaled the absence of an otherwise imminent US, it became an inhibitory CS


Summation Test


Testing the combined effects of a known excitatory CS and if possible inhibitory CS


Retardation Test


Method for determining whether a stimulus is inhibitory is to measure how long it takes to turn the stimulus into an excitatory CS

Acquisition should be slowed down with a CS that is initially inhibitory




he transfer of the effects of conditioning to similar stimuli




the opposite of generalization, in which a subject learns to respond to one stimulus but not to a similar stimulus


The Importance of Timing in Classical Conditioning


The timing of events can affect:

o How strong the conditioning will be
o Whether a CS will become excitatory or inhibitory
o Exactly when the CR occurs


short-delay conditioning


The CS begins a second or so before the US

*Usually produces the strongest and most rapid conditioning


simultaneous conditioning


The CS and US begin at the same moment

conditioned responding is much weaker than in short-delay conditioning

possibly due to lack of predictability if presented at the same time

the predictiveness of a CS is an important determinant the degree of conditioning and whether this conditioning is excitatory or inhibitory


CS Predictiveness


To the extent that a CS is a good predictor of the presence of the US, it will tend to become excitatory

To the extent that a CS is a good predictor of the absence of the US, it will tend to become inhibitory


trace conditioning


The CS and US are separated by some time interval in which neither stimulus is present

[since CS is no longer physically present, the subject must rely on a “memory trace” of the CS if conditioning is to occur]

As the CS-US interval is increased, the level of conditioning declined systematically


long-delay conditioning


The onset of the CS precedes that of the US by at least several seconds, but the CS continues until the US is presented

Like in trace conditioning, the strength of the condition responding decreases as the CS-US interval increases, but the effects are not as pronounced, since the subject does not have to rely on a memory trace of the CS


backward conditioning


CS is presented after the US

Level of conditioning is markedly lower than in simultaneous or short-delay conditioning

The weakness of backward conditioning points to a limitation of the contiguity principle—besides in their temporal proximity, the order of the stimuli is important

*After a sufficient number of trials, a backward CS becomes inhibitory
→The onset of the CS signals a period of time in which the US will be absent
→As long as the backward CS is present, the subject can be certain that no US will occur


temporal coding hypothesis


In classical conditioning, more is learned many simple
association between CS and US

The individual also learns about the timing of these two events

This learning affects when the CR occurs

This hypothesis can explain why CR may occur just before the onset of the US in the long-delay conditioning – the subject has learned that a delay of a certain duration separates the onset of the CS and the onset of the US


Rescorla & Correlation


Based on his results of conditioned suppresion procedures with rats, Rescorla concluded that the traditional view of classical conditioning, which states that the contiguity of CS and US is what causes an association to develop is incorrect

He proposed that the important variable in classical conditioning is not the contiguity of CS and US but rather the correlation between CS and US

If a CS predicts that the US is likely to occur, the CS will become excitatory

If a CS predicts that the US is not likely to occur, the CS will become inhibitory


second-order conditioning


CR is transferred from one CS to another

First-order CS– CS is paired with US

Second-order CS: another CS paired with the first-order CS which elicits the CR, *without ever being directly paired with the US


evaluative conditioning


second-order conditioning in humans

e.g. nonsense syllable repeatedly paired with a positive or negative word (which developed into a CS through language and experience), subjects later give the nonsense syllable a positive or negative rating

e.g. pictures of people’s faces (second-order stimuli) was paired with either positive or negative adjectives (first-order stimuli)
• subject later rated the faces as “liked” if they had been paired with positive adjectives and “disliked” if they had been paired with negative adjectives

[evaluative conditioning has long been used in advertising]


Applications in Behavior Therapy


systematic desensitization
aversive counterconditioning
treatment of nocturnal enuresis (bedwetting)


systematic desensitization


Manly used as treatment for phobias

Patient is exposed to phobic object gradually, so that fear and discomfort are kept to a minimum and extension is allowed to occur

Treatment has three parts:
• construction of a fear hierarchy
• training and relaxation
• gradual presentation of items in the fear hierarchy to the patient

After the fear hierarchy is constructed, the patient is given training in progressive muscle relaxation, (Wolpe 1958)


aversive counterconditioning


developing an aversive CR to stimuli associated with undesirable behavior

The term counterconditioning is used because the technique is designed to replace a positive emotional response to certain stimuli (such as alcohol, drugs, smoking, sexual deviation) with a negative one

Effectiveness is variable


Treatment of nocturnal enuresis (bedwetting)


Bell-and-pad method
• water-detecting devices placed beneath the sheets and a single drop of urine will activate the device during the development of child

Bell is a US that elicits two responses in the child:
• awakening
• tightening of those muscles necessary to prevent further urination

The goal of the procedure is to transfer either or both of these responses to an internal CS – the sensations associated with having a full bladder

By repeatedly pairing a full bladder with the bell, the response of awakening and-or tightening the muscles so as to retain one’s urine should eventually be elicited by the full bladder alone, before the bell sounds