Classical Conditioning I
Module 04 Reading
Chapter 4
Classical Conditioning I: Basic Principles
CHAPTER OUTLINE
The Basics of Classical Conditioning
The Unconditioned Stimulus (US), Conditioned Stimulus (CS),
Unconditioned Response (UR), and Conditioned Response (CR)
Acquisition
Number of CS-US Pairings
Strength of the US
Does the CS precede the US?
Contiguity and CS-US timing
Extinction
Resistance to extinction
Appetitive and Aversive USs
Check Your Learning
Additional Results From the Laboratory
Generalization and Discrimination
Generalization
Discrimination
Higher-Order Conditioning
Sensory Preconditioning
Sign Tracking
Conditioned Emotional Responses (CERs)
Conditioned Inhibition: When the CS Signals US Omission
Pavlov’s Original Procedure
A word about contingencies
Measuring Conditioned Inhibition
Retardation tests
Summation tests
Check Your Learning
Learning in the Real World: Classical Conditioning and Food Preferences
Have you ever eaten an unusual food and later been sick to your stomach? If so, it is likely that you will make every effort to avoid consuming that unusual food from then on. For example, one of the authors ate several pieces of “Hawaiian Delight” pizza several hours before a virus caused him to be violently sick to his stomach. He has now successfully avoided this unusual pizza for over 25 years! His experience is an example of the learning process known as classical conditioning.
The Basics of Classical Conditioning
Ivan Pavlov (1849-1936), a Russian physiologist who won a 1904 Nobel Prize in Medicine and Physiology for his studies of digestive processes, was the first person to extensively and systematically study the process of classical conditioning. Pavlov’s research on classical conditioning was conducted in the most controlled, scientific manner possible for his time period. According to Goodwin (2005)
Beginning in 1910 (but not fully equipped until 1925, the Institute [of experimental Medicine] built a special laboratory for Pavlov’s conditioning research. Later known as the Tower of Silence, it featured extensive soundproofing techniques to ensure that the dogs would respond only to the stimulus being studied at the time and not to any extraneous stimuli. ……there were eight experimental chambers, four on each of two floors that were separated by an intermediate floor. Each research chamber was fully insulated and separated from other chambers by a corridor. To further reduce noise and vibration, the building itself was supported by beams immersed in sand and surrounded by a sand- and straw-filled moat! Experimenters were separated from the dogs by the double wall that is evident in [Figure 4-1]. (pp. 282-283)
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Fig. 4-1 Goes Here
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A part of Pavlov’s basic procedure for studying digestive processes consisted of placing meat powder on the tongues of the dogs that served as his research subjects. He carefully collected and measured (by weighing) the gastric juices and saliva that occurred when the dogs tasted the meat powder—the taste of food results in the involuntary reflex of salivation and other digestive processes. During the course of his research, Pavlov noticed that other stimuli, such as the sight of the researcher or the experimental equipment, caused the dogs to salivate before they received the meat powder. Because it appeared that these events that preceded delivery of the meat powder were capable of eliciting the salivation reflex, the dogs seemed to anticipate that the meat powder was coming. In short, a form of learning known as classical conditioning had taken place.
Because researches at this time thought that behaviors like the salivation reflex were innate and not changeable by experience, these observations intrigued Pavlov. Consequently, he and his assistants began to study this phenomenon under more scientific, controlled conditions. Their basic procedure was to activate a metronome just prior to delivering the meat powder. (Contrary to popular belief, Pavlov did not ring a bell.) Following several pairings of the metronome and the meat powder (each pairing is called a trial), they presented just the ticking sound of the metronome. As with his original observations, Pavlov found that salivation occurred when the dogs heard just the sound of the metronome. Further research indicated that two types of stimuli and two types of responses are involved in classical conditioning.
The Unconditioned Stimulus (US), Conditioned Stimulus (CS), Unconditioned Response (UR), and Conditioned Response (CR)
Pavlov designated the stimulus that automatically or reflexively elicits the behavior in question as the unconditioned stimulus (US). The meat powder is the US in the example of conditioning in Pavlov’s laboratory. After it was paired with the meat powder several times and was able to elicit the target response (salivation) by itself, the ticking sound of the metronome became a conditioned stimulus (CS). The researchers designated the response that the US reflexively (automatically) elicited as the unconditioned response (UR). They labeled the response that the CS (ticking sound of the metronome) elicited as the conditioned response (CR).
Putting these stimuli and responses together, we can diagram the process of classical conditioning as follows:
First : A US reflexively elicits a UR
US UR
Then: A CS is paired with the US several times.
US UR
+
CS
Finally: The researcher presents the CS by itself.
CS CR
In Pavlov’s research both the UR and CR were salivation. However, you should not jump to the conclusion that these two responses will be identical in all instances of classical conditioning. This effect was summarized by Kimble (1961) who indicated “In many experiments, the conditioned response appears to be weaker than the unconditioned response or to represent only a component of it” (p. 53). For example, because it is part of an innate reflex, the food powder US is very likely to elicit a stronger response (the UR) than the one that the CS elicits (the CR) as well as other digestive processes, such as stomach contractions.
Once the basic process was established, researchers were quick to begin projects to determine what factors affected classical conditioning. The initial research focused o two main aspects: Acquisition and Extinction of the CR.
Acquisition
As the name implies acquisition is the process of acquiring the new response, the CR. Initially, researchers believed that the CR developed and that it was unusual for a strong CR to be shown after only one paring of the CS and US. We will see later in this chapter and in Chapter 5 that these assumptions have been challenged.
*** What are some of the factors that you believe will affect the acquisition of the CR (i.e., result in a stronger CR)? Write your answers down before reading further.
If you thought of such factors as the number of times the CS and US are paired, the strength of the US, and whether the CS precedes the US, then you are definitely on the right track. One other factor that is very important that you may not have considered is the length of time that elapses between when the CS is presented and when the US occurs. Let’s examine each of these variables more closely.
Number of CS-US pairings. Generally speaking, the more times the CS and US have been paired, the stronger the CR (Hilgard & Marquis, 1935). Certainly, this relation reaches a point where further pairings do not result in stronger conditioning.
Strength of the US. Up to a point, the stronger the US, the stronger conditioning will be. For example, if you grab the handle of a hot (US) skillet (CS), you will be conditioned to fear skillets (CR) more rapidly than if the skillet handle had only been warm.
Does the CS precede the US? Conditioning is stronger if the CS precedes the US. Researchers have attempted to produce conditioning by presenting the US and then following it with the CS. This procedure, called backward conditioning, produces very weak conditioning, if any conditioning at all (Kimble, 1961).
Contiguity and CS-US timing. Early studies of classical conditioning indicated that contiguity of CS and US was an important factor in the development of strong conditioning (Hilgard & Marquis, 1940). When two stimuli are contiguous, they occur together in time and space. This definition holds true for the CS and US in classical conditioning. However, there are some qualifications to our definition.
First, strict contiguity, where the CS and US are presented at exactly the same time does not produce the strongest conditioning. This procedure is called simultaneous conditioning. Similarly, conditioning will not be as strong if the US occurs at the time that the CS terminates or immediately after CS termination. Researchers call this procedure delayed conditioning.
By varying the time between presentation of the CS and presentation of the US, early researchers determined that the optimum interval for producing the strongest conditioning was approximately .50 sec (Reynolds, 1945; Woodworth & Schlosberg, 1954). Shorter or longer intervals appeared to result in weaker conditioning (Brogden, 1951).
*** Does that last statement seem a bit strange? Have you already read something that might contradict it? Give this question some thought and write down your answer before you read further.
If you remembered the pizza scenario that opened this chapter, then you are definitely on the right track. In that situation the person experienced the CS (novel taste) occurred long before the illness occurred. According to what you just read, under these conditions classical conditioning should be very weak if it occurs at all. Initially, such anecdotal reports were not taken seriously; they did not represent scientific findings produced under controlled conditions (Garcia, 1981). Then, in 1966 Garcia, Ervin, and Koelling reported that they had conditioned a taste aversion in rats with one pairing of a novel taste (CS) and irradiation (US) that produced illness (UR) even when the CS and US were separated by an expanded time interval. The anecdotal reports had received experimental verification; classical conditioning can, under certain conditions, occur with a long delay separating the CS and US. We will have much more to say about the topic of conditioned taste aversions in the next chapter where we will examine recent trends in classical conditioning.
Second, conditioning will be weaker if the CS comes on and then is terminated before the US is presented. This procedure is known as trace conditioning because the US is not directly associated with the CS, but rather with the memory or trace of the CS Figure 4-2 shows the various CS-US arrangements we have described.
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Fig. 4-2 Goes Here
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Extinction
Because the US is not presented when researchers test for the presence of the CR, the CR gradually decreases in strength. Researchers call this procedure of presenting the CS without the US extinction.
*** Why does it make sense for the CR to gradually diminish or extinguish with repeated presentations of just the CS? Write down some potential reasons before reading further.
If your reasons included the fact that the CS did not reflexively elicit any response under normal conditions, give yourself a pat on the back. Viewed in this context, extinction is a procedure whereby the CS gradually loses its power to elicit the CR. Some theorists have proposed that right after conditioning, the CS is an excellent predictor that the US is going to occur. After several CS-only (extinction) trials the CS is no longer as good a predictor of US occurrence and its ability to elicit the CR gradually decreases.
Resistance to extinction. Researchers have devised several methods to measure how long it takes to extinguish the CR (typically called resistance to extinction). Notice that these measures of extinction clearly are related to the strength of conditioning that was established during acquisition; the stronger the conditioning the grater the resistance to extinction. The following are traditional measures of resistance to extinction:
- Number of CS only trials – Typically, the stronger the conditioning the greater the number of CS only trials required to extinguish the response.
- Amplitude or magnitude of the CR – As the number of CS only trials increases the amplitude or magnitude of the CR decreases. Examples of measures of amplitude or magnitude are the amount of saliva that is secreted and the degree of change in heart rate or respiration.
- Latency of the CR – As the number of CS only trials increases, the time between the onset of the CS and the display of the CR increases. For example, the onset of salivation and the display of an eyeblink are slower to occur as the number of CS only trials increases.
Spontaneous recovery. Assume that you have just spent all day extinguishing a conditioned salivary response in one of the dogs you are testing; the CS no longer elicits a CR. Imagine your surprise when you return the next day, present the CS, and it elicits a CR. Admittedly, the CR is substantially weaker than it was when you started extinction yesterday; however, ou cannot deny that you just recorded a CR. What has happened?
Pavlov called this phenomenon spontaneous recovery. It occurs when a presumably extinguished CR reappears following the passage of time (Kimble, 1961). Typically, the greater the passage of time between extinction sessions, the greater the spontaneous recovery (see Brooks & Bouton, 1993).
At this point you may be wondering if you can ever completely extinguish the CR. The occurrence of spontaneous recovery prompted researchers to determine if the CR can be extinguished or if it would always reappear to some degree following the passage of time. Their research indicated that the CR can be fully extinguished; however, if the original conditioning is strong, extinction can be a very lengthy process (Brogden, 1951). Researchers have shown that spontaneous recover occurs in both animals and humans (Razran, 1939). Finally, it is worth noting that as few as one presentation of the US during extinction may be sufficient to return the CR to its original, pre-extinction strength and extend extinction considerably.
Appetitive and Aversive USs
Even though many of our examples have used meat powder at the US, you should not get the impression that it is the only US that researchers have used to study classical conditioning. Far from it.
*** Recall the scenario about the unusual food and illness that opened this chapter—here’s a chance to do some reviewing. What were the US, UR, CS, and CR in that situation? Write down your answers before reading further.
The US was the illness, whereas the pain and discomfort automatically produced by the illness constituted the UR. The CS was the sight and taste of the unfamiliar food and the CR consisted of feeling nauseous and avoiding the unfamiliar food after conditioning too place.
Another favorite US with classical conditioning researchers has been to administer a brief puff of air to the open eye of the test subject, frequently a rabbit or a young child (Steinmetz, 1999) The puff of air reflexively elicits an eye blink that can be conditioned easily.
Likewise, some researchers have used a mild electric shock as the US. Often they apply this shock to one foot of a test dog; the dog reflexively raises its foot. This foot-raising behavior is easily conditioned to a CS, such as a tone or blinking light.
If you stop and think about it, these, if not all, USs can be put into two categories: appetitive and aversive. Appetitive USs, such as meat powder, are ones that we seek out or approach. Aversive USs, such as electric shock or a puff of air to the eye, are ones we dislike and try to avoid. Table 4-1 summarizes several appetitive and aversive USs and the URs that they elicit.
Table 4-1. Selected Examples of Appetitive and Aversive USs and the URs They Elicit.
___________________________________________________________________________
USUR
___________________________________________________________________________
APPETITIVE USs
Voluntary Muscles
Object touches lipSucking
Digestive System
Good foodSalivation
Emotional System
Sexual stimulationErotic feeling
Reproductive System
Genital stimulationVaginal lubrication, penile erection, orgasm
AVERSIVE USs
Voluntary Muscles
Sharp or hot stimuliJerk away and cry
Blows, shock, burnsWithdrawal
Circulatory System
High temperatureSweating, flushing
Sudden loud noiseBlanching, pounding heart
Digestive System
Bad foodSickness, nausea, vomiting
Respiratory System
Irritation in noseSneeze
Throat cloggedCough
AllergensAsthma attack
Emotional System
Painful blowFear
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Adapted from: Baldwin and Baldwin (2001)
Check Your Learning
Classical conditioning is a form of learning that occurs when a neutral stimulus that was paired with an unconditioned stimulus comes to elicit a conditioned response.
The unconditioned stimulus (US) reflexively elicits the unconditioned response (UR). Following its pairing with the US, the conditioned stimulus (CS) comes to elicit a conditioned response (CR).
The CR may be weaker than or a component of the UR.
Acquisition is the process of learning a new response.
The number of CS-US pairings, strength of the US, whether the CS precedes or follows the US, and contiguity f the CS and US are factors that affect the strength of conditioning.
Extinction occurs when the CS is presented without the US and the CR decreases. Resistance to extinction is a measure of extinction and can be assessed by the number of CS only presentations, amplitude/magnitude of the CR, and latency of the CR.
Spontaneous recovery occurs when a previously extinguished CR reappears with the passage of time.
Appetitive USs are approached, whereas aversive USs are avoided.
Additional Results From the Laboratory
After establishing the basics involved in the acquisition and extinction of a classically conditioned response, early researchers turned their attention to other intriguing research questions. Among the areas they investigated were: higher-order conditioning, generalization and discrimination, sign tracking, conditioned emotional responses, and classical conditioning in humans.
Generalization and Discrimination
Generalization. If classical conditioning is going to serve an adaptive function, then the CR should also be elicited by stimuli that are similar to the CS that was conditioned.
*** Reread the last statement. Why is this statement true? Write down some reasons before reading further
Because other, similar stimuli also may be predictive of a US, it makes sense to also pay attention to them. For example, if you have experienced the pain (US) of being stung by a wasp (CS), then you will want to avoid similar insects like yellow jackets and hornets. The ability of stimuli that are similar to the original conditioned CS to elicit a CR is called generalization, and, as we’ve just discussed, generalization can assist in adaptation to the environment (Moore, 1972).
Pavlov’s (1928) original research on generalization involved conditioning a CR to one specific ticking speed of the metronome (CS). Following conditioning, he tested for CRs to different ticking rates. The more similar the ticking rate he tested to the rate of the original CS, the stronger the CR. An experiment by Bass and Hull (1934) demonstrated generalization of the galvanic skin response (GSR) in college students to a tactile stimulus that had been paired with electric shock. Such studies reflect the pervasive nature of generalization.
Discrimination. You can view discrimination as the converse of generalization; instead of making CRs to stimuli that are similar to the CS, responding is shown only to one stimulus, typically the CS that was conditioned to the US (Kimble, 1961). For example, assume that during conditioning a 5ooHz tone served as the CS and a mild electric shock to a dog’s hind foot is the US. The researcher also presents tones of 100Hz, 300Hz, 700Hz, and 900Hz frequencies; however, when these tones are presented, they are never followed by the US. During conditioning the dog reflexively raises its foot (UR) when the US is presented. After conditioning is complete the researcher tests for CRs to all of the tones and finds that a CR is shown only to the 500Hz tone (the CS). The dog has learned to discriminate between the tones that did not predict the US and the one that did predict the US. Likewise, humans learn numerous discriminations, such as which insects sting and which do not sting.
Higher-Order Conditioning
Quite likely you can think of several stimuli in your own life that have become CSs because they were paired with a US. How about the package that contains your favorite snack food? Do you begin to salivate (CR) at the sight of that package (CS)? If you were trapped in an abandoned refrigerator as a child and almost suffocated (US that elicits fear), does the sight of a refrigerator cause you to become anxious (CR)? You likely can point to a large number of instances of classical conditioning in your life.
However, there are likely to be numerous other stimuli that do not seem to have been paired with a US that also elicit similar reactions. Consider the following scenario. Last week you and your former best friend, Bill (CS), had a major argument (US) which made you very angry (UR). Now, whenever you see Bill, you become angry (CR). On several recent occasions you have seen Bill talking to John and now you become angry when you see John even though you have no reason to be angry with him. What’s going on here?
*** Using what you know about classical conditioning and the pairing of stimuli, see if you can answer this question; the above paragraph ontains all the necessary information. Write down some possibilities before reading further.
If you started with the original conditioning situation and its result, your’re on the right track. Let’s diagram that situation:
Original Conditioning: US (violent argument) UR (anger)
+
CS (Bill)
Then:CS (Bill) CR (anger)
Then, Bill talked with John several times, hence
CS (Bill) CR (anger)
+
CS (John)
After several conversations
CS (John) CR (anger)
The process by which a second CS, John in our example, can come to elicit a CR b being paired with a previously conditioned CS, Bill in our example, is called higher-order classical conditioning (Murphy & Miller, 1957; Razran, 1955). Using our classical conditioning symbols, we can diagram the general paradigm for higher-order conditioning as follows:
CS1 (already conditioned) CR
+
CS2 (to-be-conditioned stimulus)
After pairing:
CS2 CR
In this situation researchers refer to the already conditioned CS as the first-order CS; it had direct contact with the US and when it is presented alone it is only one step removed from the US. The stimulus that is paired with the first-order CS to produce higher-order conditioning is called the second-order CS; it is two steps removed from the US.
*** Focus your attention on the CR that is elicited by the second-order CS (John in our example). Will this CR be as strong as the CR that is shown when the first-order CS is presented? Write down your answer, with some supporting reasons, before reading further.
The CR elicited by the second-order CS will be weaker than the CR elicited by the first-order CS because the procedure used to establish higher-order conditioning also is the procedure used to produce extinction (i.e., presenting the CS without the US). Just the two are paired to produce conditioning to the second-order CS; hence, the effectiveness of the first-order CS will gradually decline. Researchers have attempted to carry higher-order conditioning even further by pairing second- and third-order CSs. As you might expect, this conditioning procedure produces very weak, if any, conditioning.
Sensory Preconditioning
Sensory preconditioning, like higher-order conditioning, involves pairing two CSs together. However, in sensory preconditioning (Brogden, 1939) the pairing is done before the experimenter pairs on of the CSs with a US. We can diagram this arrangement thusly:
Two CSs are paired
CS1
+
CS2
Then, CS1 is paired with a US
US UR
+
CS1
Following conditioning of a CR to CS1, the experimenter presents CS2 by itself. If sensory preconditioning has occurred, the CS2 will elicit a CR.
CS2 CR
The establishment of a CR to CS2 under these conditions was important because it showed that conditioning can occur in situations other than a CS-US pairing; two CSs can become associated by being paired. Sensory preconditioning also is important because it provides another mechanism, in addition to generalization, by which stimuli that have never been paired with a US can come to elicit a CR. For example, assume that a school child frequently sees dogs (CS1) on the playground at school (CS2). Then one day he is bitten (US) by a dog in his own front yard. Now, he doesn’t want to go out on the playground at school for recess. The dog (CS1) was paired with the painful bite (US) that elicited fear and panic. Now, because dogs (CS1) and the playground (CS2) were associated, the playground also elicits the fear CR.
Sign Tracking
As they began to study classical conditioning in animals other than dogs, researchers were compelled to measure behaviors other than salivation. For example, the pigeon is an excellent laboratory subject for the study of learning.
*** Despite the popularity of pigeons for the study of learning, they do pose a problem if you are interested in studying classical conditioning. We seriously doubt that you will find it feasible to study the formation of a salivary CR in these birds. What response could you classically condition in pigeons? Write down some possibilities before reading further.
If you included pecking in your list, give yourself a pat on the back. Pecking is one of the responses that researchers frequently use in their studies of classical conditioning in pigeons. Here’s how they do it. In the procedure known as sign tracking (Hearst, 1975; Locurto, Terrace, & Gibbon, 1981; Tomie, Brooks, & Zito, 1989), researchers present a CS (typically a plastic disc that can be illuminated that is located on one wall of the test chamber near where a food US (e.g., grain) is presented. This pairing is repeated a number of times (just as Pavlov paired the ticking metronome and meat powder a number of times when he established the salivary CR). Initially, the pigeon appears to ignore the disc when the light is turned on. However, as the number of pairings increases, the pigeon attends to and even begins to peck at the disc when the light is turned on in anticipation of receiving the food US. The quickness of beginning to peck and the number of pecks are both measures of classical conditioning. Thus, in sign tracking animals investigate or explore stimuli that predict relevant events (e.g., USs).
Conditioned Emotional Responses (CERs)
Imagine that a rat has learned to press a lever for food (se Chapter 6 for more on this type of learning). The rat has learned this response quite well and makes a large number of responses during its daily 15-minute test session. During another daily test session the same rat has received several pairings of a flashing light (CS) and a mild electric shock (US).
*** What do you think will happen when the experimenter presents the flashing light CS suring a lever-press session? Write down your answer (and reason) before reading further.
Researchers, such as Estes and Skinner (1941) who developed this procedure, noticed that CSs such as a flashing light or a tone are easily conditioned to an electric shock US. A rodent’s natural response to a stimulus, such as the flashing light in our example, that signals danger is to freeze. Freezing is an adaptive response that lessens the chances that the rodent will be noticed by a predator. In situations, such as the one we have described, researchers have given the term conditioned emotional response (CER) to the freezing behavior that is conditioned,.
Now, what is the effect of adding the blinking-light CS to the lever-press situation. Because it is a signal for the rat to freeze (a CER, it is incompatible with and suppresses lever pressing. Researchers frequently presents a CS that elicits a CER in another situation, such as lever pressing, to determine the strength of the CER conditioning. The greater the reduction or interference in responding in the test situation, the stronger the CER conditioning. This is definitely a situation where less responding (e.g., lever pressing in our example) is more (stronger CER conditioning). The effect of the CER on the target behavior is called conditioned suppression.
Conditioned Inhibition: When the CS Signals US Omission
Up to this point, we have considered classical conditioning situations where the CS signaled that the US was going to occur. Pavlov (1927) called this type of conditioning conditioned excitation because the CS causes or excites the production of a CR. On the other hand, Pavlov also developed the procedure he called conditioned inhibition where the CS signals omission of the US.
*** How would you go about conditioning a CS to signal the omission of a US? You cannot just present a stimulus and then not present the US; that’s essentially what a yet-to-be-conditioned stimulus does normally. Give this problem some thought and write down a possible solution before reading further.
Pavlov’s Original Procedure
Pavlov (1927) solved this dilemma in a rather ingenious manner. He conditioned an excitatory CS (CSexcite) by pairing it with meat powder; this is the standard classical conditioning procedure that we’ve already examined several times. On other trials he presented CSexcite with a second stimulus that was destined to become the inhibitory CS (CSinhib) and did not follow this stimulus pair with the US. This arrangement can de diagrammed as follows (see also Marchant, Mis, & Moore, 1972):
CSexcite
+ no US
CSinhib
The test subject gradually learns the discrimination that when the CSexcite is presented by itself, the US will follow (CR is established) and that when CSexcite and CSinhib are presented together, the US will not follow (no CR is established). For example, you are training your dig, Sherlock, to sit. Whenever Sherlock successfully sits when you say nthe word “sit,” she is rewarded with a treat. Soon Sherlock is salivating (CR) when she hears “sit” (CSexcite) because “sit” and the treat (US) have been paired. However, when Sherlock gets in trouble you sat “sit” (CSexcite) and “bad dog” (CSinhib). Sherlock becomes conditioned to not salivate on these occasions; “bad dog” has become a CSinhib that tells her that the treat (U) will not be forthcoming. It is important to keep in mind that inhibitory conditioning takes place in the context of excitatory conditioning (Baker & Baker, 1985; LoLOrdo & Fairless, 1985).
A word about contingencies. Generally speaking, the use of the term contingency in classical conditioning refers to the frequency that the CS and US occur together (Kimble, 1961). Obviously, the more frequently they occur together, the more likely classical conditioning will occur.
*** If you stop and think about it, logic tells us there are three types of contingencies. Write down these three types (with a brief description for each one) before reading further.
The three types of contingencies are positive, zero, and negative. In classical conditioning when a positive contingency is in effect a Csexcite is present and signals the occurrence of a US. When a negative contingency is in effect a Csinhib is present and signals the omission of the US. A zero contingency means that the CS and US do not occur together in any reliable or predictable manner; hence, classical conditioning does not take place.
Measuring Conditioned Inhibition
Whereas measuring a CR that occurs to a CSexcite is a relatively simple procedure, measuring something that does not occur, such as not making a response to a CSinhibit, poses a problem. Although researchers have devised several procedures for assessing conditioned inhibition, retardation tests and summation tests are the most common procedures.
Retardation tests. Retardation tests for conditioned inhibition test the speed of conditioning an excitatory CR to a CSinhibit (Rescorla, 1969). The basic procedure is to pair a CSinhibit with a US and and compare the number of pairings required for this CSinhibit to become a CSexcite with the number of pairings required for a second, neutral CS to become a CSexcite. Because of its initial inhibitory effect, the CSinhibit retards the formation of the new CS-US association. Hence, the CSinhibit should requite more pairings with the US to establish the excitatory CR; the number of extra pairings; the number of extra pairings provides a measure of conditioned inhibition.
Summation tests. If a CSinhibity is presented with an already established CSexcite, then the magnitude of the CR elicited by the CSexcite should be reduced, relative to the CR shown to just the CSexcite, because of the conditioned inhibitory effect of the CSinhibit. Thus, in the summation test the CSinhibit counters the excitatory power of the CSexcite. It is important to note that the CSexcte presented during the summation test is not the CSexcite that the experimenter presented during the conditioning of CSinhibit.
Check Your Learning
Generalization occurs when stimuli that are similar to the CS elicit a CR.
Discrimination is the converse of generalization. It occurs when a CR is elicited by one stimulus, but not others.
Higher-order conditioning involves pairing two stimuli together following conditioning to one of them. A CR is elicited by the second stimulus following pairing.
Sensory preconditioning occurs when two stimuli are paired before one of the stimuli is conditioned. Following conditioning the second stimulus elicits a CR.
Sign tracking occurs when animals investigate or explore stimuli that predict relevant events (e.g., USs).
Emotional responses can be classically conditioned. When an animal freezes at the presentation of a fear-evoking CS, it is showing a conditioned emotional response (CER).
Conditioned inhibition occurs when the CS signals omission of the US. The retardation test and the summation test measure conditioned inhibition.
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Learning in the Real World: Pokémon and Classical Conditioning
Most likely, when we assume the role of consumer, we are well aware of all of the advertisements that that are trying to convince us to buy this or that product. We steadfastly assert our ability to choices on our own and not be influenced by the media; at least that’s what we think. It is quite likely that our behavior is being manipulated without our knowledge. Consider the following experiment.
Olson and Fazio (2001) informed their college student volunteers that they were taking part in a study of video surveillance and vigilance. The researchers told the students that hundreds of images would be presented randomly on a computer screen. Each image was paired with either a positive word (e.g., excellent or awesome) or image (e.g., puppies or a hot-fudge sundae) or a negative word (e.g., terrible or awful) or image (e.g., a cockroach or a man wielding a knife). Among the hundreds of images that the students saw were Pokemon cartoon characters; they were of special interest to the researchers.
*** Describe the conditioning that took place in this situation before reading further.
The Pokemon cartoon characters were the CS. Some were paired with positive words or images; whereas, other Pokemon characters were paired with negative words or images. Following all the presentations, the students evaluated the Pokemon characters. The positive or negative words or images that were paired with the Pokemon characters served as the US. (Because there was no true US in this situation that was capable of reflexively eliciting a response, this experimental arrangement is very similar to higher-order conditioning.) The good feelings that the positive words and images elicited and the bad feelings that the negative words and images elicited served the role of the UR.
How do you think the students reacted to the Pokemon characters when they evaluated them? The researchers found that participants reported positive evaluations of the Pokemon characters paired with positive words or images and negative evaluations of the Pokemon chararcters that had been paired with negative words or images. Moreover, the students were unable to recognize or describe the connection between their evaluation of the Pokemon characters and the fact that they had been paired with positive or negative words or images. In short, the experimental procedure created an attitude in the participants without the participants’ knowledge. This research indicates clearly that advertisers may be conditioning our attitudes and trying to control our buying behavior in a very unobtrusive manner and to a much greater extent than we may believe possible. We encourage you to be examine repetitive advertising very carefully.
Margin Definitions
Classical conditioning
A form of learning in which an initially neutral stimulus is paired with an unconditioned stimulus and becomes a conditioned stimulus that elicits a conditioned response
Unconditioned stimulus (US)
Stimulus that reflexively elicits a response
Conditioned stimulus (CS)
Stimulus that, following pairing with the US, comes to elicit a response
Unconditioned response (UR)
Response that is reflexively elicited by the US
Conditioned response (CR)
Response that is elicited by the CS
Acquisition
The process of learning a new response, such as the CR
Extinction
Presentation of the CS without the US. Leads to a reduction in the strength and frequency of the CR
Resistance to extinction
A measure of the strength of the CR. How long it takes to extinguish the CR
Spontaneous recovery
Reappearance of a CR that was thought to be extinguished
Appetitive US
A US, such as food, that is sought out
Aversive US
A US, such as electric shock, that is avoided
Generalization
The ability of stimuli that are similar to the CS to elicit a CR
Discrimination
The converse of generalization. The test subject learns to respond to one stimulus, but not other
Higher-order classical conditioning
A previously neutral stimulus comes to elicit a CR after being paired with an already conditioned CS
Sensory preconditioning
Repeated pairing of two neutral stimuli before one of them is paired with a US.
Sign tracking
Tendency to investigate/explore stimuli that predict relevant events (USs)
Conditioned emotional response (CER)
The CS signals an aversive US. Because a CER CS can suppress ongoing behavior, the term conditioned suppression is appropriate.
Conditioned excitation
The CS excites or causes the production of a CR
Conditioned inhibition
The CS signals the omission of a US
Retardation test
Test for conditioned inhibition that measures the speed of conditioning an excitatory CR to an inhibitory CS
Summation test
Test for conditioned inhibition in which an inhibitory CS and an excitatory CS are presented simultaneously to determine how much the inhibitory CS counters the effects of the excitatory CS
References
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