Book and Article questions

A biological imperative faced by all creatures is to survive long enough to reproduce. Because of this necessity, behavior related to survival and reproduction often appears to be built into the organism. Thus, organisms are born with a range of behavior that aids survival and reproduction.

not need to be learned; it results from the organism’s evolutionary history as a species. The complex

dependable when this behavior is primarily based on genetic endowment. For most animals, survival at birth depends on being able to breathe, digest food, and move

about. When a worm is dangled over a young robin’s head, this stimulus elicits opening of the mouth and chirping. The behavior of the chick is the result of biological mechanisms and is elicited

. Presumably, in the evolutionary history of robins, chicks that presented a gaping mouth and chirped were fed more often those that did not, contributing to

by an infant ensures more effective care from the child’s parents. Parents engage in a variety of caretaking behaviors, which may have resulted in cessation of crying. Usually, parental responses

Behavior relations that predominantly are based on the genetic endowment are described as phy- logenetic

past generations of organisms that engaged in such behavior survived and reproduced—passing on their genes over generations. Thus, species history provides an organism with a basic repertoire

behavioral characteristics were naturally selected, as they occurred through no human action or intervention.

Fixed-action patterns or FAPs

engage in the FAP when the appropriate releasing stimuli are presented. Fixed-action patterns have been observed and documented in a wide range of animals and over a large number of behaviors

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male sticklebacks intrude on its territory during the mating season. The female spider Cupiennius salei

Basically, the bird continues behaving as if the egg is present even though it has been removed. The Sciurus vulgaris

in while storing nuts for the winter:

The squirrel . . . buries nuts in the ground each fall, employing a quite stereotyped sequence of movement. It picks a nut, climbs down to the ground, and searches for a place at the bottom of a tree trunk or a large boulder. At the base of such a conspicuous landmark it will scratch a hole by means of alternating movements of the forelimbs and place the nut in it. Then the nut is rammed into place with rapid thrusts of the snout, covered with dirt with sweeping motions and tamped down with the forepaws.

Ethologists refer to such predictable and stereotypic behaviors as to sug- gest that these behaviors are built in and immutable. These researchers are looking for heritable genetic factors, which appear to account for behavior of all members of the species. On the other

- able, at least to some degree. So, given the adaptive ability of most animals, we refer to this behavior as a modal action pattern or MAP

Turdus migratorius very similar in construction. It is clear, however, they do not all build in the same location, or use the same materials. There is substantial individual variation in all phases of nest construction, suggest-

form. Once started, a yawn progresses through

stop—almost like a sneeze. Yawning typi- cally occurs in bouts, with a highly variable inter-yawn interval, averaging about a minute.

variation about this value. Also, the pattern of

is quite stable over several weeks of obser- vation and there is no compensation between yawning frequency and duration. Those who yawn for shorter durations do not do it more frequently than others with longer durations; also, people with longer duration yawns do not yawn less often than those with shorter

- cise stimulus that sets off yawning is hard to

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bedtime as well. Yawning after waking is often accompanied by stretching of the arms, while yawn- ing before bedtime usually only involves yawning without stretching. As you can see, yawning involves stereotypic behavior of phylogenetic origin that often occurs during periods of low vig- ilance and reduced alertness—perhaps acting to momentarily reinstate surveillance and monitor- ing of the environment. [Note: arousal or physiological activation of the brain is a disputed cause

contagious yawning is

Sacket, 2015 for birds.] Reaction chains are similar to FAPs, but with one major difference—each set of responses

the behavior are removed. In the previous squirrel and nuts example, the animal continues to dig a hole and bury the nonexistent nut, even if the nut is removed. In contrast, a reaction chain requires

performance produces stimuli that set off the next series of responses in the chain; these behaviors in turn produce the stimuli followed by another set of responses. Presenting a stimulus that ordinarily occurs in the middle part of the sequence activates the chain at that point rather than at the begin- ning. Also, unlike FAPs, if the stimuli that activate behavior are removed, the sequence is disrupted.

Gasterosteus aculeatus

describe an idealized behavioral sequence. During the mating season, the reaction chain is initiated when a male stickleback sees a female and begins a zigzag dance, displaying his red underbelly. For a receptive female with eggs, the male’s display functions as a stimulus that causes the female to arch her back and reveal her swollen abdomen. This initiates swimming by the male to a previously constructed nest. The female follows and enters the nest with her tail protruding, causing the male to nibble at the

base of her tail and initiate the egg- laying sequence. Once the female has deposited her eggs, the male ousts her from the nest, enters the nest, and fertilizes the eggs, thereby completing the reaction chain.

This courtship chain may be terminated at any point if the

or inappropriate to function as a stimulus for the next link in the chain. Thus, red-bellied males that skillfully perform the zigzag dance are more likely to attract females to their nests and fertil- ize eggs than males that execute the dance less skillfully. Sexual selection, by providing more chances to mate, ensures that genes related to skillful execu- tion of the dance are more rep-

resented in the next generation and that the offspring have a high probability of successful courtship and reproduction.

- ciples that describe the relationship between a sudden loud noise and a startle response, also hold for the

relationships he discovered over a century ago generalize to a remarkable variety of stimulus–response relations. When food is placed in a dog’s mouth, the salivary glands produce saliva. This relationship

others are particular to a species. Thus, humans are born with an array of responses elicited by

response—turning toward the stimulation with the mouth open, which then receives the nipple.

serves a similar function—getting fed. Because these relationships are relatively invariant and bio- logically based, we refer to the eliciting or activating event as the unconditioned stimulus (US). The related behavior following the stimulus is called the unconditioned response (UR). The term unconditioned -

called a

produces the unconditioned response when presented with an unconditioned stimulus. You do not choose

the UR of salivation; that is, salivation is said to be elicited by the US. This is the way the animal is built. However, there are times and conditions described below where the US does not elicit the UR. When repeated presentations of the US leads to a reduction of the UR, we call the process habituation.

Around 350 BC, Aristotle developed principles of association that were rediscovered by psychologists

below the knee, causing a kick, may vary from a modest to a heavy blow. The intensity of the eliciting US describe these effects.

1. The law of the threshold is based on the observation that at very weak intensities a stimulus will not elicit a response, but as the intensity of the eliciting stimulus increases, there is a point at which the response is elicited. Thus, there is a point below which no response is elicited and above which a response always occurs. The uncertainty region, where roughly 50% of the stim- uli that are presented produce a response, is called the threshold.

2. The law of intensity–magnitude describes the relationship between the intensity of the eliciting stimulus and the size or magnitude of the elicited response. As the intensity of the US increases, so does the magnitude of the elicited UR will evoke a slight jerk of the lower leg; a stronger tap will produce a more vigorous kick of the

is used to smash into the knee, the result is a broken kneecap and no movement for a long time. 3. The law of latency concerns the time between the onset of the eliciting stimulus and the appear-

these two events. As the intensity of the US increases, the latency to the appearance of the elic- ited UR decreases. Thus, a strong puff of air will elicit a quick blink of the eye. A weaker puff will also elicit an eye blink, but the onset of the response will be delayed.

- acteristics and one of these, habituation, has been shown in animals as simple as protozoa and as complex as humans.

One of the more documented secondary properties habituation. Habituation is observed to occur when an unconditioned stimulus repeatedly elicits an unconditioned response

eventually fail to occur at all. For example, Waw-

onto a slide on which the protozoa Spirostomum ambiguum were mounted. The dropped weight initially elicited a contraction or startle response that steadily declined to near zero with repeated stimulation.

An interesting report of human habituation, in a dangerous setting, appeared in the July 1997 issue of National Geographic small island of Montserrat has been home to

- tively silent volcano on the island reawakened in July 1995. Suddenly, the quiet existence that had characterized living on Montserrat was rudely interrupted. Before the major eruption of the vol- cano, a large group of inhabitants refused to evac- uate the island, even though these people suffered through several small volcanic explosions:

staying with friends in St. John’s, about as far north of the volcano as you can get. . . . Peo- ple could get passes to visit the unsafe zone,

morning. “If you have animals and crops, you

walked back to his truck. “You have to come look after them and hope nothing happen.” As he spoke, the volcano made a crackling sound like

falls, everybody look.”

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uated to near zero with repeated eruptions of the volcano. A similar process is observed when people

some time the sound is barely noticed. This decrease in the human startle response is demonstrated in a

South Dakota State. Brady notes that a human demonstration of habituation is not an experiment as the

large initially, but gets progressively smaller as habituation continues. Second, if the unconditioned stimulus is withheld for some time, the habituated response recovers, a process called spontaneous recovery. Third, when habituation is repeatedly produced, each series of stimulus presentations

generates progressively more rapid habituation. In other words, habituation occurs more quickly on

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On a daily basis, animals are exposed to aversive events that activate a complex stress response

repeated presentation of the stressful event. In a recent review of the HPA axis and stress neurobi-

Overall, a good deal of literature supports HPA habituation as an example of response habitua- tion. . . . These criteria describe the well-documented phenomenon of habituation itself, its ability to be enhanced by increased frequency or number of presentations, variations in its induction related to the strength of stimulus, and its ability to be dishabituated by a novel stimulus. . . . However, [some] criteria are not supported. This is due largely to the lack of demonstration of spontaneous recovery [of HPA activity after a period without the stressor].

The authors conclude that the HPA-axis response to repeated stress is more complicated than response habituation. The decline in HPA activity to stressful events does involve habituation, but

exposures to stressful stimuli. Habituation is a conserved behavioral process that has come about because of a phylogenetic

history. Those animals that habituated were more likely to survive and produce offspring—passing on their genes to the next generation. An herbivore that runs away each time the grass rustles gets less to eat than one that stands its ground. A rustling sound of grass may indicate the presence of a predator, or simply the wind blowing. Repeated, unnecessary activation of respondent mechanisms also causes stress to the animal, which is not good in terms of health and physiology.

In addition to phylogenetic history, the behavior of an organism is affected by environmental expe- rience. Each organism has a unique ontogenetic history or lifetime of conditioning. Changes in behavior, as a result of such experiences, are called learning, consisting of moment-to-moment interactions of the organism’s behavior with the environment. Events in the physical and social

phylogenetic history to determine when, where, and what kind of behavior will occur at a given moment.

For example, salivation is involved in the digestion of food. People do not learn to salivate to the taste of food; this is a phylogenetic characteristic of the species. After some experience learning that McDonald’s goes with food, you may salivate to the sight of the golden arches of McDonald’s, especially if you are hungry and like hamburgers. Salivating at the sight of McDonald’s arches occurs because of respondent conditioning—you were not born that way. It is, however, important to note that respondent conditioning and other learning processes evolved because they provided some sort of reproductive advantage. Those organisms whose behavior came under the control of

behavior did not. Through Darwinian evolution and selection, respondent conditioning became a means of behavioral adaptation. In other words, organisms with a capacity for respondent or asso- ciative learning were more likely to survive and reproduce—increasing their genes in the population

Respondent conditioning involves the transfer of the control of behavior from one stimulus to another by S–S association. In Chapter 1, we saw that the sound of a bell could come to elicit sali- vation after the bell had been associated with food. This kind of conditioning occurs in all species, including humans, and is common in everyday life. Imagine that you are out for an early morning walk and pass a bakery where you smell fresh donuts. When this happens, your mouth begins to water and your stomach starts to growl. These conditioned responses occur because, in the past, the

conditioned stimulus (CS), and salivation to the light is called the conditioned response (CR).

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of behavior control to new and often arbitrary aspects of the environment. To experience this sort of conditioning, try the following: Read the word lemon and consider the last time you ate a slice of lemon. Many people salivate at this CS because the word has been correlated with the sour taste of the fruit. This shift in controlling stimulus from food to word is possible because inputs to the visual system end up activating the neurons innervating the salivary gland.

Because the CR is a response elicited by the CS, it is often called a respondent. The terms conditioned response and respondent are interchangeable throughout this text. The process of cor-

relating the CS with the US so that the CS comes

respondent conditioning. Technically, respondent conditioning involves establishing a conditional

Note that the association is between the CS and lemon and the real fruit in the

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point. The word “association” is sometimes taken to mean an internal mental process that a person or other animal performs. We hear people say, “The dog salivates when the bell is sounded because it has associated the sound with the food.” In con- trast, a behavior analyst points to the association or

the past. In other words, the association is between

events—it does not refer to mental associations to explain the conditioning. The word lemon

The usual measures -

and latency make sense as behavioral measures because respondent conditioning often involves

orienting to a stimulus or going to a place or location, are elicited and often confused with operant behavior. When the CS controls behavior based on a respondent-conditioning procedure, the behav-

consequences is operant, even when this behavior involves actions of the smooth muscles, glands,

conditioned taste aversion (CTA). Now consider a different procedure where the CS is a particular place or location and the

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the location paired with the solution, an effect known as conditioned place preference (CPP). Notice that the tasty solution functioned as a CS for CTA conditioning, but as a US for CPP learning. Therefore, the same stimulus or event may function as either a CS or a US, depending on its relation to other stimuli in the situation.

When stimuli or events occur near in time or are paired together, they often become similar in function. While close temporal proximity between CS and US is usually required, conditioning

CTA there is a substantial delay between the CS-taste onset and US-sickness, but strong conditioned

is followed by an effective US and acquires some of the behavior functions related to the US, an equivalence relation referred to as stimulus to stimulus (S–S) conditioning

by the CS response, and the person may die due to heart failure. For most practical purposes, the conditioning procedure should arrange close temporal proxim-

ity, pairing, or contiguity of the CS and US, but research shows that it is the contingency, predictive- ness, or correlation between the stimuli that is critical. Thus, the US should occur more frequently when the CS is present than when it is absent—the CS should predict or signal the US

- where from moment to moment. Although many nonhuman studies of respondent conditioning are cited in this textbook, these principles also account for an enormous amount of human behavior.

In humans, conditioning by contingency happens all the time. When the features of a person are -

life enhances many social relationships. Mother–infant bonding is a product of good USs from the

the sound of her voice, and perhaps her heartbeat, many aspects that can become very potent signals

commitment to that person. Advertising often involves enhancing product appeal by linking the item

Star Wars preferences also transferred to other stimuli resembling those used during conditioning.

The attractiveness of the human face has been an important component in human dating and

Additional research, using brain-imaging technology, has revealed neural activity to presentations of attractive faces in the reward areas of the brain. In the advertising industry, many television

faces can transfer to commercial products by conditioning procedures.

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active during conditioning. The results showed increases from preconditioning to postconditioning

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ditioning trials in accord with the S–S model of conditioning proposed by Rescorla and Wagner

conditioning works on the reward centers in the brain related to the dopamine neurons in the ventral striatum. The results also suggest how commercial advertisements linking products with attractive

of goods and services.

- tion of the CS is called respondent acquisition

turning on the tone for a brief period, and then placing food in a dog’s mouth. Anrep measured the CR as the number of drops of saliva during 30-s intervals wherein the tone

that the amount of salivation to the tone increases rapidly

its maximum, called the asymptote. In other words, with repeated presentations of the CS and US, the magnitude of the conditioned response increases. Once the conditioned

- tations have no additional effects.

It is important to note that the asymptote for the con- ditioned response depends on the intensity of the uncondi- tioned stimulus. As the intensity of the US increases, the magnitude of the UR also increases up to a point. The mag- nitude of the UR limits the maximum associative strength of the CR. Thus, the more food a dog is given the greater

there will be more salivation than if it is presented with 30

- ated with 30 g of food. It is clear that these relationships are limited by an organism’s physiology. If a dog is given 450 g of steak, it will probably salivate at maximum strength, and a change to 900 g will have no further effect. Similar limits

response to light, magnitude of the knee jerk in response to a tap, and the degree of startle in response to noise.

Notice that the conditioned response of salivation appears identical to the unconditioned response. When conditioning to the tone has occurred, turning it on will elicit salivation. This response to the tone seems to be the same as the salivation produced by food in the dog’s mouth. In fact, early theories of learning held that the tone substituted for the food stimulus. This implies that the CS–CR relationship is the same as the US–UR relation. If the CS–CR and the US–UR relationships are the same, then both should follow similar laws and principles. And the govern the US–UR relationship, as you have seen.

If the CS–CR and US–UR relationships are the same, then the law of intensity–magnitude should hold for conditioned stimuli and responses. Thus, a rise in the intensity of the CS should increase the magnitude of the CR. In addition, the CS–CR relation should follow the law of latency. An increase in the intensity of the CS should decrease the latency between the CS onset and the

not -

ditioned stimulus decreases the strength of the conditioned response. In the experiment by Anrep -

tude and latency of salivation. If Anrep had increased the sound, there would have been less sali-

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respondent extinc- tion. The procedure involves repeatedly presenting the CS and not presenting the US. Figure 3.5B

- sented the CS but no longer fed the dog. As you can see, the amount of salivation declines and reaches a minimal value by the seventh trial. This minimum level of the CR is often similar to the

respondent level of this

before any known conditioning has occurred. Extinction can be valuable as a therapeutic procedure for reducing or removing unwanted emotional responses such as claustrophobia or arachnophobia.

component. The phobic CR will then gradually decrease with repeated trials. A distinction should be made between extinction as a procedure and extinction as a behavioral

process. The procedure involves presenting the CS but not the US after conditioning has occurred. As a behavioral process, extinction refers to the decline in the strength of the conditioned response when an extinction procedure is in effect. In both instances, the term extinction is used correctly. Extinction is the procedure of breaking the CS–US association, resulting in the decline of the CR.

The decline in the strength of the CR is often rapid. This statement is true for the conditioning of salivation, but other types of conditioned responses may vary in resistance to extinction. Even with salivation, Pavlov noted that as the time between trials increased, the CR declined more slowly. A test trial is any instance in which the CS is given in the absence of the unconditioned stimulus. Of course, repeated test trials are the same as extinction. The slower extinction of salivation with longer

Spontaneous recovery is the observation of an increase in the CR after respondent extinction has occurred. Recall that after repeated presentations of the CS without the US, the CR declines to respondent level. Following extinction of the response to respondent level, after some time has

powder, and the US was food in the dog’s mouth. As you would expect, the sight of meat powder eventually elicited a conditioned response of salivation. When extinction began, the dog responded

no salivation to the sight of food powder, but after 20 min of rest without stimulus presentations, the CS again elicited a conditioned response. Note, however, that the amount of salivation on the

- ship during extinction. He went on to suggest that “internal inhibition” came to block the connection between stimuli and responses. Pavlov viewed conditioning phenomena as an index of brain pro-

- ing physiological processes, and one of these was an active but temporary “dampening” of associative connections between the CS and the conditioned response. Pavlov called this apparent physiological blocking of the CS–CR relationship “internal inhibition.”

In contrast to Pavlov’s hypothetical phys-

spontaneous recovery suggests that the CS– CR relation is weakened by extinction, but the context or features of the situation in general maintain some level of control over the condi-

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regulate behavior. For example, background odors, general illumination of the room, the presence of particular researchers, the passage of time, and all the events that signal the start of a conditioning series come to exert some control over the conditioned response. Each time a recovery test is made, some part of the situation that has not yet been extinguished evokes the CR. This gradual decline in contextual stimulus control through repeated extinction also accounts for progressively less recov- ery of the conditioned response. The role of extinction of contextual CSs in spontaneous recovery

Pavlov conducted a large number of conditioning experiments and discovered many principles that respondent general-

ization. Respondent generalization occurs when an organism shows a conditioned response to val- ues of the CS that were not trained during acquisition. For example, respondent acquisition occurs

animal will salivate at maximum level. To show generalization, the researcher varies some property

the magnitude of the conditioned response is measured. Figure 3.7 shows possible results of such an experiment. As you can see, the amount of salivation declines as the test stimulus departs in both direc- tions from the value used in training. This graph, which plots stimulus value against magnitude of response, is called a gener- alization gradient.

Interestingly, a similar generalization gradient may not occur if the intensity rather than the tonal quality of the CS is varied. If decibels rather than cycles-per-

- ization test, a different result might occur. A few studies have shown that as the

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Heinemann and Chase suggest that there may be consistent increases in the strength of the CR as the

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conditions do not remain exactly the same from trial to trial. Consider a situation in which a pred-

- tions would probably not last long. This is because the events that occurred during conditioning are never precisely repeated—each approach of a predator produces variations in sounds, sights, and smells. Even in the laboratory, where many features of the environment are controlled, there is some variation in stimuli from one trial to the next. When a bell is presented and followed by food, the dog may change its orientation to the bell and thereby alter the sound; room humidity and other factors may also produce slight variations in tonal quality. Because of generalization, a CS–CR relationship can be strengthened even though the stimulus conditions are never exactly the same from trial to trial. Thus, stimulus generalization is likely an adaptive process, allowing organisms to respond to the vagaries of life.

Another conditioning principle that Pavlov discovered is called differentiation or discrimination. Respondent discrimination occurs when an organism shows a conditioned response to one value of the stimulus, but not to other values. A discrimination-training procedure involves presenting both positive and negative conditioning trials. For example, a positive trial occurs when a CS such

is continued, however, the animal no longer salivates to the CS response to the CS differential response occurs, we may say that the dog discriminates between the tones.

Respondent discrimination is another adaptive learning process. It would be a chaotic world if an animal spent its day running away from most sounds, sights, and smells—generalizing to everything. Such an animal would not survive and reproduce as there would be no time for other essential activities such as eating, drinking, and procreating. Discrimination allows an organism to budget its time and responses in accord with the requirements of the environment. In the predator example, noises that are reliably associated with an animal that considers you a main course should become CS

for such behavior. Notice, how-

observation suggests that familiar events or stimuli do not elicit as intense a reaction as novel ones. The same is true for respondent conditioning, where novelty of the CS or US increases its effective-

respondent acquisition. Considerable research indicates that pre-exposure to the CS weakens subsequent conditioning

with the US—the CS-pre-exposure effect Latent inhibition denotes the inhibition of learning of the CS–US relation by pre-exposure of the CS, as revealed by an acquisition test following the conditioning phase.

which is followed by drug-induced illness. Compared to animals without pre-exposure to the taste

acquisition. You may have had similar experiences. For example, you eat a juicy steak with your meal,

ketchup. Now consider what would happen if you had eaten sauce béarnaise repeatedly with your meals

the repeated pre-exposure to the sauce béarnaise without illness, it is unlikely that you will condition to the taste of the sauce. In other words, you will not show avoidance of the sauce for your next steak dinner. Latent inhibition and CTA have been studied extensively, and the neurophysiological under-

Other research has focused on the novelty of the US by giving pre-exposure to the US before

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slower conditioning on the acquisition test—a result called the US-pre-exposure effect.

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to the drug is not due to simple habituation of the unconditioned stimulus. Research has shown that the context in which the drug US is injected can function as a CS. Even when the drug is injected

alone, aspects of the context or background acquire CS functions. When the sweet saccharin CS is subsequently conditioned in the same context, the contextual cues that signal the upcoming injection block conditioning to the sweet saccharin CS, resulting in weak or no avoidance of the sweet solu-

There are several ways to arrange the temporal relation- ship between the presentation of a CS and the uncon-

procedure in which the CS is presented a few seconds before the US occurs. This procedure is called delayed conditioning

Delayed conditioning is considered the most

such as salivation. In the diagram, the CS is turned on, and 3 s later the US is presented. The interval between the onset of the CS and the onset of the US

- ness of conditioning. For autonomic responses, such as salivation, blood pressure, skin temperature, hor- mone levels, and sweat secretion, a CS–US interval of between 5 and 30 s appears to be most effective. A brief CS–US interval of about 0.5 s seems to be opti- mal for the conditioning of quick skeletal responses, such as a knee jerk, eye blinks, and retraction of a limb from a hot surface. In human eye-blink condi- tioning, a delay of 0.4 s between the CS and the US produces the fastest conditioning in young adults, but a longer delay of about 1 s is more effective with older

conditioning serves as a model system for analysis of the neural mechanisms participating in respondent or

Another temporal arrangement is called simultaneous conditioning, where the CS and US are presented at the same time. This procedure is shown in Figure 3.8B,

where the CS and US are presented at the same moment. For example, at the same time that the bell

predict or signal the impending occurrence of the US in simultaneous conditioning. Based on this observation, many researchers have emphasized the predictiveness of the CS as the central feature

it provides information that “tells” the organism a US will follow. In simultaneous conditioning, however, there is no predictive information given by the CS, and yet some conditioning occurs. One possibility that predictiveness of the CS is usually required for conditioning, but contiguity or close

The procedure for trace conditioning is shown in Figure 3.8C. The CS is presented for a brief period,

is placed in a dog’s mouth. The term trace conditioning comes from the idea of a “memory trace,”

and US are separated by only a few seconds. When compared with delay conditioning with the same interval between the onset of the CS followed by the US, trace conditioning is not as effective—pro- ducing a weaker conditioned response. Contemporary research has extended trace conditioning to taste

As shown in Figure 3.8D, backward conditioning stipulates that the US comes on and goes off -

not produce a conditioned response. If you place food in a dog’s mouth and ring a bell, the bell does not elicit salivation when presented later. Most conditioning experiments have used arbitrary stimuli

These researchers reasoned that following an unsuccessful attack by a predator, the sights, sounds, and smells of the attacker would be associated with pain from the attack. Consider a situa-

as the prey animal would learn to avoid lions.

Rats were placed in an experimental chamber and fed a sugar pellet in a particular location. While

the chamber was made com- pletely dark for 1, 5, 10, or 40 s. When the light in the chamber came back on, a toy hedgehog

To make this experiment clear, eating sugar pellets was viewed as the laboratory equivalent of grazing, the shock represented an attack, and the appearance of the toy hedgehog substituted for the predator. Two control groups were run under identical con- ditions, except that one group saw the hedgehog but did not get shocked, and the other group received the shock but did not see a hedgehog.

On the next day, each animal was returned to the situation and a number of responses were mea- sured. Compared with the control groups, backward conditioning was found after a delay of 1, 5, and 10 s but not after 40 s. Relative to control animals, experimental subjects showed greater avoidance

avoidance of the toy animal. This experiment shows that backward conditioning is possible with a biologically relevant CS. Despite this outcome, most contemporary researchers suggest that backward

- tioning several conditioning trials, the control of the response to the US is transferred to the non-functional

transfer of control to other events that have not been directly associated with the unconditioned stimulus. These events gain control over the response because of the association with an estab- lished conditioned stimulus. Thus, second-order conditioning involves presentation of a second CS

2 along with an already conditioned CS

1

- er-order conditioning is important because it extends the range of behavioral effects produced by

in people. Consider a person who refuses to sit with friends in the backyard on a nice summer day. The

1

2 1

2

Basic research on simple and complex (i.e., including contextual effects) respondent condi- tioning has major applied importance. One example of this involves factors that affect drug use and abuse. Several experiments have shown that conditioned stimuli (CS) can produce drug-like effects in both humans and other animals. In addition, stimuli that have been fol- lowed by drugs sometimes produce internal conditioned responses (CR) that are opposite to the unconditioned effects of the drug. For example, when animals are injected with insulin (US), the unconditioned response is a reduction in blood sugar levels (UR). The response to a stimulus (CS) that has been followed by insulin is exactly the opposite—blood sugar levels increase (Siegel, 1975).

Similar counteractive effects have been found with drugs other than insulin. For exam- ple, amphetamine reduces appetite, but a CS correlated with it increases food intake (Poulos,

stimulus associated with pentobarbital counteracts the drowsiness ordinarily associated with

Effects such as these suggest that respondent conditioning plays a major role in drug tol- erance. Here is how it works. With repeated presentation of a CS (injection process) and US (drug) contingency, the conditioned response (CR) gains in strength and increasingly opposes the unconditioned (UR) effects of the drug. This means that larger and larger amounts of the US will be needed for the user to experience the same degree of effect. In everyday life, condi- tioned stimuli arise from the time of day that a drug is taken, the way it is administered (using a needle), the location (in a tavern or at home), and social events (a party or dance). Notice that tolerance, which is a reduction in the effect of the drug (UR), is not due to habituation, but rather it is the result of the counteractive effects (CR) to the injection process and setting (CS). When more of a drug (US) is needed to obtain the same drug effects (UR), we talk about drug tolerance components of drug tolerance.

To consider drug tolerance as a conditioned response helps to explain instances of drug overdose. Heroin addicts are known to survive a drug dose that would kill a person who did not regularly use the drug. Despite this high level of tolerance, approximately 1% of heroin addicts die from drug overdose each year. These victims typically die from drug-induced respiratory depression. Surpris- ingly, many of these addicts die from a dose similar to the amount of heroin they usually took each

of tolerance. The opiate addict, who can usually tolerate extraordinarily high doses, is not tolerant

experiment to test these ideas. In one study, rats were injected with heroin every other day for 30 days. The amount of heroin

was gradually increased to a dose level that would produce tolerance to the drug. On non-heroin -

trose injections were given in one of two distinctive contexts—the ordinary colony room that the rats lived in, or a different room with constant white noise. A control group of rats was injected only with the dextrose solution in the two situations. The researchers predicted that experimental animals would develop a tolerance to the drug; this tolerance would occur if aspects of the room in which

heroin given to experimental animals. The same high dose of heroin was given to the control group, who had no history of tolerance. Half of the experimental animals received this larger dose in the room where the drug was usually administered. The other addicted rats were injected with the higher dose in the room where they usually received a dextrose injection.

Figure 3.10 shows the results of this experiment. As you can see, the large dose of heroin killed almost all of the animals in the control group. For the two groups of animals with a history

usually injected with heroin. Only 32% of the rats died in this condition, presumably because the CSs set off the opposing conditioned responses. This inference is supported by the mortality rate of rats in the different room group. These rats were injected with the double dose of heroin in a room that had never been associated with heroin administration. Twice as many animals in this condition

- pared with the same room group. It seems that the effects of context during this kind of respondent conditioning can be a matter of

-

in which the conditioning has occurred, and in humans involves conditioning of both

What happens when the drug-related CS is presented without the drug US, as in the classical extinction procedure? In this case the elicited respondents often are called “cravings,” and the process is known as conditioned withdrawal. The CS elicits reactions that ordinarily are countered by the US. However, when the US is not delivered and if those CR reac- tions occur, the subject experiences with- drawal effects. A heroin addict can have withdrawal symptoms immediately ter- minated by a heroin injection. If you are accustomed to having a cigarette after a meal, the craving you experience can be alleviated with a smoke.

generally considered to be internal and autonomously controlled processes. In this procedure, a CS is followed by a US drug that suppresses immune-system function, such as the production of antibodies. [Note: drugs like cyclophosphamide are commonly administered to suppress rejection of a transplanted organ.] After several presentations of the CS–US contingency, the CS is presented

- tematically investigate and describe this phenomenon. Clearly, the next question is whether the immune system can also be conditioned to increase an immune reaction. It appears that it can. In

also Hadamitzky, Engler, & Schedlowski, 2013 reported learned immunosuppression using a condi-

placebo effects on a person’s physiological well-being? Many studies have shown that people who receive a sugar

-

One thing that these types of studies indicate is that there is much greater two-way interaction between the environment and physiological mechanisms than had been suspected. Organisms are

Philosoph- ical Transactions of the Royal Society of behavioral conditioning of the immune system including ongoing clinical applications.

We so far have examined CS and US relationships in isolation, ignoring for the most part the con- text or background in which these events occur. To investigate the effects of context on respondent behavior, researchers have arranged situations involving compound stimuli. In these cases, and to

a single conditioned response. In an everyday example, the odor of food at a bakery or restaurant probably becomes a CS

however, such as the name, the order clerk, the location of the store, and the outdoor signs also are correlated with eating. These additional features of the fast-food experience become conditioned

- tioning procedures related to compound stimuli result in the behavioral processes called blocking and overshadowing.

overshadowing. A compound stimulus is arranged consisting of two -

such as food. Pavlov found that the most salient element of the compound stimulus came to regulate exclusively the conditioned response. In this case the loud tone and not the faint light would become a CS for salivation. The tone is said to overshadow conditioning to the light. This happens even though the weak light could function as a CS if it was originally presented by itself and followed by a US.

Overshadowing is demonstrated by either of two procedures. Simultaneous presentation involves the presentation of CS

1 and CS

2 -

1 is followed by CS

2 1

CS 2 1 1

CS 1

- ing procedure. When the US is positive as with food presentations, overshadowing is shown as a decrease

1

demonstrated by an increased 1

Research with rats has shown overshadowing of CTA induced by an opportunity to run in a

1 2 , overshad-

1

all rats received 1-bottle tests for 15 min with salty

shown in Figure 3.11 for overshadowing and con- trol rats. Data analysis indicated that rats in both overshadowing and control groups did not differ in wheel running and increased wheel turns over daily trials. Notice that rats in the overshadowing condition showed higher intake of salty solution than the control group—indicating less avoidance of the CS

1 , the target taste. In contrast, rats given

the overshadowing procedure drank less of the sucrose solution than control animals, indicating more avoidance of the CS

2

together indicate that the overshadowing stimu-

2

1 ,

1

and CS 2

This effect is called blocking, which describes a situation in which CS 1 when followed by the US

blocks a subsequent CS 2 –US association. In blocking, a CS

1 1

stimulus or CS 2 is presented at the same time as the original CS

1 1

CS 2 1

evokes the CR but the second stimulus or CS

2 1

-

On test trials, the tone will elicit salivation but the light will not. The previously conditioned tone blocks conditioning of the light stimulus.

conditioned suppres- sion aversive US such as an electric shock. After several conditioning trials, the CS becomes a condi-

ave ave

commonly called anxiety or fear. Once the CSave has been conditioned, its effects may be observed by changes in an organism’s operant behavior. For example, a rat may be trained to press a lever for food. After a stable rate of response is established, the CSave is introduced. When this occurs, the animal’s lever pressing is disrupted, presumably by the CER elicited by the CSave. Basically, we could say that the CSave frightens the animal and it stops pressing the bar. Conditioned suppression is a widely used procedure in respondent conditioning, and as you will see later it is important in the study of human emotions.

blocking. Two groups of rats were used: a blocking group and a control group. In the blocking ave

Following this, the rats received 8 trials during which the compound stimulus, tone and light, was

have the 8 trials of tone and light followed by shock. Both groups were tested for conditioned sup- pression of lever pressing in the presence of the light. In this test, the light was presented alone and suppression of bar pressing for food indicated the occurrence of the conditioned emotional response

lever pressing in the blocking group. In other words, prior conditioning with the tone alone blocked or prevented conditioning to the light. Functionally, the light acted as a CSave in the control group but not in the blocking group.

Blocking and overshadowing have been interpreted as cases of redundant stimuli. Only the salient CS element signaling the US presumably is required to elicit the CR; the other elements of

while other features do not. All stimulus manipulations are conducted in some place, be it the lab- oratory or an everyday setting like a classroom, and noticeable elements of that environment often

CS–US contingency that tends to restrict the connection to only salient stimuli.

-

-

- tioned taste aversion and a US for conditioned taste preference. Both respondent acquisition and extinction were described, and research examples were provided. Spontaneous recovery that occurs during respondent behavior was also discussed.

Organisms show generalization of respondent behavior over a stimulus gradient, but also

withheld to other values of the stimulus array. In addition to simple conditioning effects, tem- poral relationships between the CS and US are important as in delayed, simultaneous, trace, and backward conditioning—and the phenomenon known as second-order conditioning. The impli- cations of respondent conditioning were extended to an analysis of drug use and abuse, with some attention to context and drug tolerance. Finally, more advanced issues of complex condi- tioning and compound-stimulus effects such as overshadowing and blocking were introduced. The Rescorla–Wagner model of conditioning was described, and expressed as a mathematical

decrease during extinction.

- duction Some neat data on conditioning and tolerance are provided and discussed.

www.youtube.com/watch?v=LcojyGx8q9U One application of respondent conditioning is called systematic desensitization—an effective treatment for anxiety and phobia. This video clip out- lines the basic procedure of graded exposure to the fear stimulus, a snake.

1. Behavior relations based on the genetic endowment of the organism are described as:

2. Complex sequences of released behaviors are called:

5. A diminution in the UR due to repeated presentation of the US is called: