Psychologists are interested in operations which affect behavior. One important class of these operations involves conditioning. On the basis of differences in the operations involved, one can distinguish between two kinds of conditioning. The first of these is classical, or reflex, conditioning. The second kind of conditioning is called operant conditioning. Classical conditioning, since it deals with reflexes, is usually said to deal with involuntary behavior, and operant conditioning with voluntary behavior. However, as will be seen later in this unit, individuals are probably capable of more voluntary control over their reflexes than had previously been supposed.
This module will cover classical conditioning of reflex behaviors. As you read the text, keep the following questions in mind.
The starting point for classical conditioning is the reflex. An unlearned reflex is a stimulus-response connection which is inherent in the structure of the organism. The two parts of the reflex are called the unconditioned stimulus (UCS) and the unconditioned response (UCR).
UCS (unconditioned stimulus) -----------------------------------------------------------> UCR (unconditioned response)
In a reflex both the stimulus and the response are unconditioned
In a reflex both the stimulus and the response are unconditioned
No conditioning (learning) is required for the unconditioned stimulus to elicit the unconditioned response. For example, if a light shines in your eye (an unconditioned stimulus) the pupil of your eye will contract (the unconditioned response). Or, when you place food (the unconditioned stimulus) on your tongue, you will salivate (the unconditioned response). No learning (conditioning) is required for these responses to occur, so they are "unconditioned."
Before any conditioning occurs, the reflex response may be considered as being under the control of the unconditioned stimulus. If the unconditioned stimulus is presented, the reflex response occurs; without the stimulus, the response does not occur. In conditioning, reflex control is extended from the unconditioned stimulus to some arbitrarily selected (neutral) stimulus which previously had no control over the reflex response. A dog does not have to learn to salivate when he has food in his mouth, but if he also salivates at the sight of his bowl being brought to him, learning has taken place.
In order for this control to develop, the neutral stimulus has to be paired
with the unconditioned stimulus, or, as one theorist puts it, the neutral
stimulus has to precede the occurrence of the response. The conditioned-
response experiment was originated by the Russian physiologist and Nobel
Prize winner, Ivan Pavlov (1849-1936). While studying the reflexes
associated with digestion, Pavlov noticed that the flow of saliva was
influenced not only by food placed in the dog's mouth, but also by the sight of
food. He knew that the flow of saliva in response to food placed in the mouth
was an unlearned response; he called it an unconditioned response. He
thought, however, that the influence of the sight of food was probably learned.
Hence, this is a learned or conditioned response. Pavlov then experimented
to find out how conditioned responses were formed. He eventually taught the
dog to salivate to various signals, such as a rotating disk or the sound of a
metronome. This proved to him that new stimulus-response associations
could be formed in the laboratory.
A response is called a
conditioned response if it
is elicited by the
A response is called a conditioned response if it is elicited by the conditioned stimulus
Pavlov prepared a dog for experimentation by performing a minor operation on its cheek. Part of the salivary gland was thus exposed to the surface. A capsule was attached to the cheek to measure salivary flow. The dog was brought to the soundproof laboratory on several occasions and placed in a harness on a table. This preliminary training was needed so that the animal would stand quietly in the harness as the experiment proceeded. A light (the conditioned stimulus) was turned on and, after a few seconds, the meat powder (unconditioned stimulus) was delivered by remote control to a pan in front of the dog. The hungry dog salivated and ate. A few more trials were given in which the light was always followed by the meat, and the meat by salivation. After several trials, the dog would salivate when the light was turned on, even though food did not follow. When this happened, a conditioned response had been established.
The usual order of events (conditioned stimulus, unconditioned stimulus, and response) can best be remembered if the conditioned stimulus is thought of as a signal that the unconditioned stimulus is about to appear. In our example, the light is a signal that food is coming. The conditioned response may be considered a simple habit because association is demonstrated to exist between the stimulus and the response, and this association is a learned one.
After conditioning, the response will follow either the unconditioned or the conditioned stimulus
Classical conditioning, as it is represented by Pavlov's model, may be defined as the formation of an association between a conditioned stimulus and a conditioned response, on the basis of an existing relationship between an unconditioned stimulus and an unconditioned response. The original response to the unconditioned stimulus is called an unconditioned response; the learned response to the conditioned stimulus is called a conditioned response.
The conditioned response, of course, resembles the unconditioned response. For this reason classical conditioning is sometimes referred to as learning through stimulus substitution. This term should be used carefully, however, since the unconditioned stimulus has not actually been replaced; it still produces the same response.
In classical conditioning, the subject simply responds to the environment. For this reason classical or reflex conditioning is also called respondent conditioning. We can summarize the steps in classical conditioning as follows:
1. Start with:
A Reflex | unconditioned stimulus| leads to | unconditioned response ( UCS --------> UCR)
2. Do the training: Pavlovian Conditioning
conditioned stimulus paired with unconditioned stimulus ---leads to a ---unconditioned response
(pairing)UCS/CS -----> UCR
3. The relationship which results: A Conditioned Response
conditioned stimulus ------> conditioned response CS ----->CR
In research on classical conditioning in humans, the eye-blink reflex is frequently used. The procedure looks like this:
1) puff of air to eye -----> blink (reflex)
UCS --------> UCR
2) puff of air to eye while bell (originally a neutral stimulus) sounds -------> blink (conditioning)
(pairing) UCS/CS-----> UCR
3) Bell sounds -----> blink (test for conditioning)
CS ------> CR
One measurement of the strength of conditioning is the magnitude of the conditioned response. Pavlov carefully measured the amount of saliva produced by the dog after different amounts of conditioning.
As might be expected, if the animal had experienced few trials in which the light and food were paired, the test for conditioning would yield very little saliva. However, if the animal had experienced many conditioning trials, a great deal of saliva would be produced by the test.
It was previously mentioned that if you present an unconditioned stimulus you will elicit a reflex response, but this is true only if the stimulus is of sufficient magnitude or intensity. It is easy to imagine a light stimulus so weak and feeble that it would have no effect whatsoever on your pupillary reflex. If this were the case, a psychologist (or student of this course) would say the stimulus intensity was below threshold. The threshold, then, is simply a name for the intensity or magnitude of a stimulus above which an unconditioned response is elicited. Below this threshold no response is elicited.
Latency can be used as a measure of response strength
Latency is the name given to the period of time which elapses between the presentation of a stimulus and the occurrence of a response. The latency of an unconditioned response depends in part on the intensity of the unconditioned stimulus. A sharp tap on the knee will elicit a faster (as well as greater) knee jerk than a very light one; a bright light will elicit a faster (and greater) papillary contraction than a dim one.
EXTINCTION AND SPONTANEOUS RECOVERY
If one continues to present the CS (in the salivation example, the light) without following the CS with the UCS (in the salivation example, the meat powder), the conditioned response (salivation) will cease to occur. The set of operations by which a previously conditioned response is eliminated is called extinction. If we continue to present the CS without following it by the UCS, we will notice a gradual tendency not to respond to the CS. At this stage the animal might be returned to his home cage for a rest period. When he is returned to the apparatus and the CS is tried again, he will give a conditioned response for several trials. This recovery of the tendency to give the conditioned response without any further training trials is known as spontaneous recovery.
Once a response has been conditioned to a particular stimulus, other similar stimuli will also elicit the same response. This phenomenon is known as stimulus generalization. For example, if a response has been conditioned to a tone of a particular pitch, the conditioned. response will also occur at higher and lower tones; the closer the tone is to the stimulus used in training, the greater the CR will be.
Generalization's counterpart is discrimination. The operations necessary to produce a discrimination combine those of conditioning and extinction, and can be illustrated by recounting an experiment of Pavlov's Pavlov conditioned dogs to salivation when a metronome was set at 100 beats per minute. Then, testing for generalization, he found that the dog would also salivate at 80 beats per minute. Now, by consistently presenting meat powder in the presence of the 100-beat-per-minute metronome and consistently failing to present it in the presence of the 80-beat-per-minute metronome, salivation was eventually brought under the control of the 1 00-beat metronome. Eventually no salivation occurred in the presence of the 80-beat-per-minute: discrimination had occurred.
PROGRESS CHECK 1
Now test yourself without looking back.
1. An unlearned reflex is composed of a(n)________________________________ and a(n)_____________________________________________.
2. In an experiment, the following sequence of events occurs:
a. A light comes on
b. Some meat powder is placed on the dog's tongue
c. The dog salivates
Name these events:
3. The intensity or magnitude of a stimulus above which an unconditioned response is elicited is called
4. Latency is_____________________________________
5. What is extinction?_________________________________
6. On Tuesday at 2 p.m., an experimenter works with a dog for an hour and extinguishes the salivation response to a tone. He then returns the animal to his cage. On Thursday at 2 p.m., he places the dog back in the conditioning apparatus. Explain what will happen, and give the technical term.
7. When a response has been conditioned to a specific stimulus, other similar stimuli will also elicit the response. This is called___________________________________________
8. Pavlov conditioned a dog to salivate at a metronome beat of 100 beats per second, but not at 80 beats per second. This is an example of________________________________________________
Now, be sure to do the exercises which follow.
A classic study (John B. Watson and Rosalie Rayner, 1920) showed that fear could be conditioned in a human being in the laboratory. When nine-month-old Albert was shown a tame white rat, he was curious but unalarmed. The next time they showed him the rat, an experimenter stood behind Albert and made a loud noise by striking a metal bar with a hammer. Albert cried. This sequence was repeated several times. After a few trials, Albert would cry at the sight of the white rat. Eventually, in fact, Albert would cry at the sight of any white furry object, such as a ball of cotton, a rabbit, or a white mask.
In classical conditioning, an unconditioned stimulus that elicits an unconditioned response must be present. In the case of Albert, the unconditioned response was________________________________________7
The unconditioned response, crying, was originally elicited in the presence of the unconditioned stimulus, the____________________________________ 10
In order to condition a reflex, the unconditioned stimulus is paired with a conditioned stimulus. In the case of Albert, the conditioned stimulus was the_______________________________________ 3
After several trials, the presentation of the conditoned stimulus produces a conditioned response. For Albert, the conditioned response was__________________________________________________ 5
Match the following, referring to the story of Albert above.
1 ) White rat______
2) Loud noise_______
a. Conditioned response
b. Unconditioned response
c. Conditioned stimulus
d. Unconditioned stimulus
Albert's crying at the sound of the loud noise was an example of a reflex. A reflex, then, consists of a(n)_________________________________________ and a(n)_______________________________________________________ _________________________________________________________________________ 4
Stimulus generalization means that once a response has been conditioned to a specific stimulus, other similar stimuli will produce the same response. Albert showed stimulus generalization in his response to a:
a. loud noise.
c. white mask.
d. white rat.
Discrimination is the antithesis of generalization. Discrimination
a. once a response has been conditioned to a specific
stimulus, other stimuli will elicit the same response.
b. an animal might respond only to a specific stimulus
and not to other similar stimuli.
c. (neither of these)
A stimulus below a certain intensity will not elicit an unconditioned
response. This specific intensity is called threshold. Which of the
following is another definition of threshold?
a. The intensity of a stimulus that elicits the greatest
b. The intensity of a stimulus above which the response
c. The intensity of a response that is elicited
d. A stimulus that elicits an intense response
3 a, b
3 white rat
4 stimulus (unconditoned) and response (unconditioned)
8 b, c
10 loud noise
Latency refers to the time between the presentation of the stimulus Match.
and the occurrence of the response. In the case of Albert, latency
could refer to the elapsed time between:
a. the presentation of the white rat and the loud noise.
b. the presentation of the loud noise and the occurrence
c. the presentation of the rat and stimulus generalization.
d. the presentation of the white rat and Albert's crying.
Conditioned responses can be eliminated, or extinguished, by con- tinuing to present the conditioned stimulus without ever following it with the unconditioned stimulus. How do you think extinction was accomplished with Albert? ______________________________________________________________________________________________________________________________________________ 5
In the process of extinction, a phenomenon called spontaneous
recovery sometimes occurs. After the response is extinguished and
the animal has a rest period, the conditioned stimulus again will elicit
the conditioned response. Which of the following is an example of
a. A dog salivates at the sound of a tone. This conditioned response is extinguished. The dog never again sali- vates at the sound of a tone.
b. A dog that was conditioned to salivate at the sound of a tone is repeatedly presented with the tone without unconditioned stimulus, food. After a while, he no longer salivates at the sound of the tone. He then is placed in his cage for a day. When the tone is again presented, he salivates.
c. A dog is repeatedly presented with the sound of a tone, followed by food, and he salivates. After a day of rest, he again salivates at the sound of a tone. ___________________________________________________________4
3 Stimulus generalization
5 None of the above
a) The tendency to respond to similar stimuli_______
b) The tendency not to respond to similar stimuli________
c) The elapsed time between the presentation of the stimulus and the response_______
d) The intensity of stimulus above which the response will occur_______
e)Eliminating a previously conditioned response_______ _____________________________________________________________________1
Refer to the case of Albert, if necessary, and explain classical (respondent) conditioning in terms of stimuli and responses. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________3
3 The unconditioned stimulus is presented with the conditioned stimulus to elicit the unconditioned response. After several trials, the conditioned stimulus alone will elicit the conditioned response.
1 a) 3
5 By continuing to present the white rat wit out ever again making the loud noise.
NOW TAKE PROGRESS CHECK 2
PROGRESS CHECK 2
1. The parts of an unlearned reflex are:
a. unconditioned stimulus.___________________________
b. conditioned stimulus. ________________________________
c. unconditioned response. ____________________________
d. conditioned response.____________________________-
2. In classical conditioning, a dog may be trained to salivate at the sound of a bell if the experimenter
presents food with the sound of the bell. In this example, give the following:
a. Unconditioned stimulus________________________
b. Conditioned stimulus ______________________
c. Unconditioned response__________________
d. Conditioned response_________________
3. Define threshold._________________________________________________
4. The period of time that elapses between the presentation of a stimulus and the occurrence of a response is called________________________________________________________
5. Describe spontaneous recovery.__________________________________________________
6. A dog has been trained to salivate at a tone of a certain frequency. If stimulus generalization is present in this case, what will happen when a tone of a near, but different, frequency is presented?__________________________________________
7. How could you show with classical conditioning that a dog can discriminate between the stimulation from a 100-beat metronome and an 80-beat metronome?_______________________________________________
6 OR MORE CORRECT MODULE 2
FEWER THAN 6 CORRECT INSTRUCTOR CONFERENCE
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