Why trace and delay conditioning are sometimes (but not always) hip...
- PubMed - NCBI
The NCBI web site requires JavaScript to function.
FormatSummarySummary (text)AbstractAbstract (text)MEDLINEXMLPMID ListApplyChoose DestinationFileClipboardCollectionsE-mailOrderMy BibliographyCitation managerFormatSummary (text)Abstract (text)MEDLINEXMLPMID ListCSVCreate File1 selected item: FormatSummarySummary (text)AbstractAbstract (text)MEDLINEXMLPMID ListMeSH and Other DataE-mailSubjectAdditional textE-mailAdd to ClipboardAdd to CollectionsOrder articlesAdd to My BibliographyGenerate a file for use with external citation management software.Create File
2013 Feb 1;. doi: 10.1016/j.brainres.. Epub
2012 Nov 23.Why trace and delay conditioning are sometimes (but not always) hippocampal dependent: a computational model.1, , , , , .1Department of Veterans Affairs, New Jersey Health Care System, East Orange, NJ, USA. a.moustafa@uws.edu.auAbstractA recurrent-network model provides a unified account of the hippocampal region in mediating the representation of temporal information in classical eyeblink conditioning. Much empirical research is consistent with a general conclusion that delay conditioning (in which the conditioned stimulus CS and unconditioned stimulus US overlap and co-terminate) is independent of the hippocampal system, while trace conditioning (in which the CS terminates before US onset) depends on the hippocampus. However, recent studies show that, under some circumstances, delay conditioning can be hippocampal-dependent and trace conditioning can be spared following hippocampal lesion. Here, we present an extension of our prior trial-level models of hippocampal function and stimulus representation that can explain these findings within a unified framework. Specifically, the current model includes adaptive recurrent collateral connections that aid in the representation of intra-trial temporal information. With this model, as in our prior models, we argue that the hippocampus is not specialized for conditioned response timing, but rather is a general-purpose system that learns to predict the next state of all stimuli given the current state of variables encoded by activity in recurrent collaterals. As such, the model correctly predicts that hippocampal involvement in classical conditioning should be critical not only when there is an intervening trace interval, but also when there is a long delay between CS onset and US onset. Our model simulates empirical data from many variants of classical conditioning, including delay and trace paradigms in which the length of the CS, the inter-stimulus interval, or the trace interval is varied. Finally, we discuss model limitations, future directions, and several novel empirical predictions of this temporal processing model of hippocampal function and learning.Published by Elsevier B.V.PMID:
[PubMed - indexed for MEDLINE] PMCID: PMC3873755 The hippocampal model which includes recurrent connections within the motor and hippocampal networks, as well as processing of within-trial events. In the motor network, CS inputs project through modifiable weights to the output node, which in turn project to motor areas that drive the behavioral response (eyeblink CR). The prediction error module receives excitatory US projections and inhibitory CR projections, and provides the response error (US-CR) as a “teaching signal” to the motor network. The hippocampal-region network receives inputs detailing the current state of all inputs at time t, including presence or absence of CSs, contextual cues, US, and CR. The hippocampal-reigon network learns to produce outputs that predict the state of all inputs at the next timestep t+1; in the process it forms new stimulus representations in its internal node layer that are sensitive to stimulus co-occurrence and association with the US. In the intact model, these new representations also provided as input to the motor network, which can then map from them to new behavioral responses. Arrows represent
filled circles = inhibitory connections.Brain Res. ;6/j.brainres..Schematic illustration of stimulus events during a single trial of conditioning. (A) Delay conditioning (ISI=4): On each trial several context-alone presentations are given (not shown), followed by CS onset (left dashed line); the CS remains present for 5 timesteps. The US appears for a single timestep (US onset marked by right dashed line) and co-terminates with the CS. Additional context-alone presentations complete the trial (not shown). (B) Trace conditioning (ISI=4) is similar, except that the CS is present for only two timesteps, producing a two-timestep trace interval (TI=2) before US arrival. (C) Long-delay conditioning (ISI=8) is similar to short-delay conditioning except that the CS is present for 8 timesteps before the US CS and US co-terminate. (D) Short-trace conditioning in which the US appears on the next timestep after CS offset. Abbreviation, ISI, in TI, trace interval.Brain Res. ;6/j.brainres..Simulation results of delay and trace conditioning depicted in Figure 2A,B. (A) For a given short ISI (here, ISI=4), the intact model acquires a delay CR more quickly than a trace CR. (B) Under the same parameters, the lesioned model can learn a delay CR but is severely impaired at acquiring the trace CR. In this figure, and in subsequent figures depicting learning curves, the mean model output is defined as the output of the motor network at timestep t-1, where t is the time of US a results shown are averaged over 5 bars represent standard error of the mean. (Results – not shown – are similar if CRs are scored as the peak output during the time interval between CS onset and US onset.) In all subsequent figures, HL refers to hippocampal-lesioned model.Brain Res. ;6/j.brainres..Short-delay (ISI=4) conditioning in the model. (A) Both intact and lesioned model can learn the eyeblink (EB) CR (CR, solid lines) while maintaining low background responding measured at the timestep before CS onset (pre-CS, dashed lines). (B) Activity of the hippocampal-region output node learning to predict the next state of the US in the intact model. (C) Individual responses of two representative hippocampal network hidden units during the last conditioning trial, one (light blue) which responds at CS onset and continues to respond throughout the CS period, and one (dark blue) which responds during the CS period, close to the time of expected US arrival. The x-axis indicates within-trial events: .=context only (no CS or US present on that timestep); c=CS u=US *=both CS and US HL, H hippocampus.Brain Res. ;6/j.brainres..Long-delay (ISI=8) conditioning in the model. (A) as in Figure 4, both the intact and HL model can learn long-delay condition but at a lower rate. (B) Hippocampal prediction of the US in the intact model that produced the responses in (A). (C) Individual responses of three representative hippocampal network hidden units during the last conditioning trial, showing that different units respond to CS onset (purple), later in the CS period (blue), or to predicted US arrival (green).Brain Res. ;6/j.brainres..Effect of varying ISI. (A) Trials to criterion on delay conditioning in the intact model varies as a function of ISI.Brain Res. ;6/j.brainres..Trace conditioning paradigm with ISI=4 and TI=2. (A, B) Across-trials responding in the intact and HL model given 100 training trials (left) and in the HL model given 10,000 training trials, right). (C) Activity of the hippocampal-region output node learning to predict the next state of the US in the intact model. (D) Individual responses of three representative hippocampal network hidden units during the last conditioning trial. As in long-delay conditioning, some nodes respond to CS onset (blue), others later in the CS period (purple), and some peak at the time of expected US arrival (brown).Brain Res. ;6/j.brainres..The “simplest” version of trace conditioning in the model, in which US onset occurs just after CS cessation (TI=0); see Figure 6D for task description. (A) The intact model lear the HL model is impaired, but learns to produce some CRs after extended training.Brain Res. ;6/j.brainres..Simulation results show that (A) cholinergic antagonists mildly affect delay conditioning but severely impair trace conditioning. In contrast, (B) mild doses of cholinergic agonists slightly enhance delay conditioning and significantly enhance performance in trace eyeblink conditioning, while (C) large doses of cholinergic agonists mildly impair delay conditioning, but severely impair trace conditioning.Brain Res. ;6/j.brainres..Activity of hippocampal hidden units at time step before US presentation during trace conditioning, showing prediction of US during learning. The first plot shows activity of the output of the Motor network. The other 10 figures show activity of the hippocampal hidden units during trace conditioning. The “AHA” moment here is roughly at trial 500 (first plot, Top left). Some hidden unit also show increase of activity around the “AHA” moment (see in particular, hidden units # 2,3,4,6,8,9); they activities become stable after the AHA moment, and are not altered by overtraining the network. Abbreviation: hh = hippocampal hidden unit.Brain Res. ;6/j.brainres..Publication TypesMeSH TermsGrant SupportFull Text SourcesOther Literature Sources
Supplemental Content
External link. Please review our .From Wikipedia, the free encyclopedia
(Redirected from )
"Pavlov's dog" redirects here. For other uses, see .
"Pavlovian" redirects here. For the Pavlovian Upper Paleolithic culture, see .
A statue of
and one of his dogs.
Classical conditioning (also Pavlovian or respondent conditioning) is a process of behavior modification in which an innate response to a potent biological stimulus become expressed in response to a previou this is achieved by repeated pairings of the neutral stimulus and the potent biological stimulus that elicits the desired response. Classical conditioning was made famous by
and his experiments conducted with dogs. Classical conditioning became the basis for a theory of how organisms learn, and a philosophy of psychology developed by ,
and others. Learning theory grew into the foundation of , a school of psychology that had great societal influence in the mid-20th century.
Classical conditioning occurs when a conditioned stimulus is paired with an unconditioned stimulus. Usually, the conditioned stimulus (CS) is a neutral stimulus (e.g., the sound of a tuning fork), the unconditioned stimulus (US) is biologically potent (e.g., the taste of food) and the unconditioned response (UR) to the unconditioned stimulus is an unlearned reflex response (e.g., salivation). After pairing is repeated (some learning may occur already after only one pairing), the organism exhibits a conditioned response (CR) to the conditioned stimulus when the conditioned stimulus is presented alone. The conditioned response is usually similar to the unconditioned response (see below), but unlike the unconditioned response, it must be acquired through experience and is relatively impermanent.
In classical conditioning, the conditioned stimulus is not simply connected to the unconditioned response. The conditioned response usually differs in some way from the unconditioned response, sometimes significantly. For this and other reasons, learning theorists commonly suggest that the conditioned stimulus comes to signal or predict the unconditioned stimulus, and go on to analyze the consequences of this signal.
provided a clear summary of this change in thinking, and its implications, in his 1988 article "Pavlovian conditioning: It's not what you think it is."
Classical conditioning differs from , in which a behavior is strengthened or weakened depending on its consequences (i.e., reward or punishment).
provided the most famous example of classical conditioning, although
published his findings a year earlier (a case of simultaneous discovery). During his research on the physiology of digestion in dogs, Pavlov developed a procedure that enabled him to study the digestive processes of animals over long periods of time. He redirected the animal’s digestive fluids outside the body, where they could be measured. Pavlov noticed that the dogs in the experiment began to salivate in the presence of the technician who normally fed them, rather than simply salivating in the presence of food. Pavlov called the dogs' anticipated salivation, psychic secretion. From his observations he predicted that a stimulus could become associated with food and cause salivation on its own, if a particular stimulus in the dog's surroundings was present when the dog was given food. In his initial experiments, Pavlov rang a bell and th after a few repetitions, the dogs started to salivate in response to the bell. Pavlov called the bell the conditioned (or conditional) stimulus (CS) because its effects depend on its association with food. He called the food the unconditioned stimulus (US) because its effects did not depend on previous experience. Likewise, the response to the CS was the conditioned response (CR) and that to the US was the unconditioned response (UR). The timing between the presentation of the CS and US affects both the learning and the performance of the conditioned response. Pavlov found that the shorter the interval between the ringing of the bell and the appearance of the food, the stronger and quicker the dog learned the conditioned response.
As noted earlier, it is often thought that the conditioned response is a replica of the unconditioned response, but Pavlov noted that saliva produced by the CS differs in composition from what is produced by the US. In fact, the CR may be any new response to the previously neutral CS that can be clearly linked to experience with the conditional relationship of CS and US. It was also thought that repeated pairings are necessary for conditioning to emerge, however many CRs can be learned with a single trial as in fear conditioning and taste aversion learning.
Diagram representing forward conditioning. The time interval increases from left to right.
Learning is fastest in forward conditioning. During forward conditioning, the onset of the CS precedes the onset of the US in order to signal that the US will follow. Two common forms of forward conditioning are delay and trace conditioning.
Delay conditioning: In delay conditioning the CS is presented and is overlapped by the presentation of the US.
Trace conditioning: During trace conditioning the CS and US do not overlap. Instead, the CS begins and ends before the US is presented. The stimulus-free period is called the trace interval. It may also be called the conditioning interval. For example: If you sound a buzzer for 5 seconds and then, a second later, puff air into a person’s eye, the person will blink. After several pairings of the buzzer and puff the person will blink at the sound of the buzzer alone.
The difference between trace conditioning and delay conditioning is that in the delayed procedure the CS and US overlap.
Classical conditioning procedures and effects
During simultaneous conditioning, the CS and US are presented and terminated at the same time.
For example: If you ring a bell and blow a puff of air into a person’s eye at the same moment, you have accomplished to coincide the CS and US.
Main article:
This form of conditioning follows a two-step procedure. First a neutral stimulus (“CS1”) comes to signal a US through forward conditioning. Then a second neutral stimulus (“CS2”) is paired with the first (CS1) and comes to yield its own conditioned response. For example: a bell might be paired with food until the bell elicits salivation. If a light is then paired with the bell, then the light may come to elicit salivation as well. The bell is the CS1 and the food is the US. The light becomes the CS2 once it is paired with the CS1
Backward conditioning occurs when a CS immediately follows a US. Unlike the usual conditioning procedure, in which the CS precedes the US, the conditioned response given to the CS tends to be inhibitory. This presumably happens because the CS serves as a signal that the US has ended, rather than as a signal that the US is about to appear. For example, a puff of air directed at a person's eye could be followed by the sound of a buzzer.
Temporal conditioning is when a US is presented at regular intervals, for instance every 10 minutes. Conditioning is said to have occurred when the CR tends to occur shortly before each US. This suggests that animals have a biological clock that can serve as a CS. This method has also been used to study timing ability in animals. (see ).
In this procedure, the CS is paired with the US, but the US also occurs at other times. If this occurs, it is predicted that the US is likely to happen in the absence of the CS. In other words, the CS does not "predict" the US. In this case, conditioning fails and the CS does not come to elicit a CR. This finding - that prediction rather than CS-US pairing is the key to conditioning - greatly influenced subsequent conditioning research and theory.
Main article:
In the extinction procedure, the CS is presented repeatedly in the absence of a US. This is done after a CS has been conditioned by one of the methods above. When this is done the CR frequency eventually returns to pre-training levels. However, spontaneous recovery (and other related phenomena, see "Recovery from extinction" below) show that extinction does not completely eliminate the effects of the prior conditioning. Spontaneous recovery is when there is a sudden appearance of the (CR) after extinction occurs.
As described above, during acquisition the CS and US are paired in one of those ways. The extent of conditioning may be tracked by test trials. In these test trials, the CS is presented alone and the CR is measured. A single CS-US pairing may suffice to yield a CR on a test, but usually a number of pairings are necessary. This repeated amount of trials increase the strength and/or frequency of the CR gradually. The speed of conditioning depends on a number of factors, such as the nature and strength of both the CS and the US, previous experience and the animal's motivational state Acquisition may occur with a single pairing of the CS and US, but usually, there is a gradual increase in the conditioned response to the CS. This slows down the process as it nears completion.
In order to make a learned behavior disappear, the experimenter must present a CS alone, without the presence of the US. Once this process is repeated continuously, eventually, the CS will stop eliciting a CR. This means that the CR has been "extinguished".
may be observed if a strong or unfamiliar stimulus is presented just before, or at the same time as, the CS. This causes a reduction in the conditioned response to the CS.
Several procedures lead to the recovery of an extinguished CR. The following examples assume that the CS has first been conditioned and that this has been followed by extinction of the CR as described above. These procedures illustrate that the extinction procedure does not completely eliminate the effect of conditioning
Reacquisition:
If the CS is again paired with the US, a CR is again acquired, but this second acquisition usually happens much faster than the first one.
Spontaneous recovery:
Main article:
Spontaneous recovery is defined as the reappearance of the conditioned response after a rest period. That is, if the CS is tested at a later time (for example an hour or a day) after conditioning it will again elicit a CR. This renewed CR is usually much weaker than the CR observed prior to extinction.
External inhibition:
If the CS is tested just after intense but associatively neutral stimulus has occurred, there may be a temporary recovery of the conditioned response to the CS
Reinstatement:
If the US used in conditioning is presented to a subject in the same place where conditioning and extinction occurred, but without the CS being present, the CS often elicits a response when it is tested later.
Renewal is a reemergence of a conditioned response following extinction when an animal is returned to the environment in which the conditioned response was acquired.
Stimulus generalization is said to occur if, after a particular CS has come to elicit a CR, another test stimulus elicits the same CR. Usually the more similar are the CS and the test stimulus the stronger is the CR to the test stimulus. The more the test stimulus differs from the CS the more the conditioned response will differ from that previously observed.
One observes stimulus discrimination when one stimulus ("CS1") elicits one CR and another stimulus ("CS2") elicits either another CR or no CR at all. This can be brought about by, for example, pairing CS1 with an effective US and presenting CS2 in extinction, that is, with no US.
Main article:
In latent inhibition, an exposure to a stimulus of little or no consequence will prevent a conditioned association with the stimulus being formed. This process will inhibit the formation of memory by preventing learning of the observed stimuli. This process is thought to prevent information overload.
This is one of the most common ways to measure the strength of learning in classical conditioning. A typical example of this procedure is as follows: a rat first learns to press a lever through . Then, in a series of trials, the rat is exposed to a CS, a light or a noise, followed by the US, a mild electric shock. An association between the CS and US develops, and the rat slows or stops its lever pressing when the CS comes on. The rate of pressing during the CS measures the strength of cl that is, the slower the rat presses, the stronger the association of the CS and the US. (Slow pressing indicates a "fear" conditioned response, and it is an example of a conditioned emotional response, see section below.)
Three phases of conditioning are typically used:
A CS (CS+) is paired with a US until asymptotic CR levels are reached.
CS+/US trials are continued, but these are interspersed with trials on which the CS+ is paired with a second CS, (the CS-) but not with the US (i.e. CS+/CS- trials). Typically, organisms show CRs on CS+/US trials, but stop responding on CS+/CS- trials.
Summation test for conditioned inhibition: The CS- from phase 2 is presented together with a new CS+ that was conditioned as in phase 1. Conditioned inhibition is found if the response is less to the CS+/CS- pair than it is to the CS+ alone.
Retardation test for conditioned inhibition: The CS- from phase 2 is paired with the US. If conditioned inhibition has occurred, the rate of acquisition to the previous CS- should be less than the rate of acquisition that would be found without the phase 2 treatment.
Main article:
This form of classical conditioning involves two phases.
A CS (CS1) is paired with a US.
A compound CS (CS1+CS2) is paired with a US.
A separate test for each CS (CS1 and CS2) is performed. The blocking effect is observed in a lack of conditional response to CS2, suggesting that the first phase of training blocked the acquisition of the second CS.
Experiments on theoretical issues in conditioning have mostly been done on vertebrates, especially rats and pigeons. However, conditioning has also been studied in invertebrates, and very important data on the neural basis of conditioning has come from experiments on the sea slug, Aplysia. Most relevant experiments have used the classical conditioning procedure, although
experiments have also been used, and the strength of classical conditioning is often measured through its operant effects, as in conditioned suppression (see Phenomena section above) and
According to Pavlov, conditioning does not involve the acquisition of any new behavior, but rather the tendency to respond in old ways to new stimuli. Thus, he theorized that the CS merely substitutes for the US in evoking the reflex response. This explanation is called stimulus-substitution theory of conditioning. A critical problem with the stimulus-substitution theory is that there is evidence that the CR and UR are not always the same. As a rule, the conditioned response is weaker than the UR. An even more serious difficulty is the finding that the CR is sometimes the opposite of the UR.
For example: the unconditional response to electric shock is an increase in heart rate, whereas a CS that has been paired with the electric shock elicits a decrease in heart rate.
It has been proposed that only when the UR does not involve the central nervous system are the CR and the UR opposites.
Main article:
The Rescorla–Wagner (R–W) model is a relatively simple yet powerful model of conditioning. The model predicts a number of important phenomena, but it also fails in important ways, thus leading to number modifications and alternative models. However, because much of the theoretical research on conditioning in the past 40 years has been instigated by this model or reactions to it, the R–W model deserves a brief description here.
The Rescorla- Wagner model argues that there is a limit to the amount of conditioning that can occur in the pairing of two stimuli. One determinant of this limit is the nature of the US. For example: pairing a bell with a juicy steak, is more likely to produce salivation than pairing a piece of dry bread with the ringing of a bell, and dry bread is likely to work better than a piece of cardboard. A key idea behind the R–W model is that a CS signals or predicts the US. One might say that before conditioning, the subject is surprised by the US. However, after conditioning, the subject is no longer surprised, because the CS predicts the coming of the US. (Note that the model can be described mathematically and that words like predict, surprise, and expect are only used to help explain the model.) Here the workings of the model are illustrated with brief accounts of acquisition, extinction, and blocking. The model also predicts a number of other phenomena, see main article on the model.
?V= αβ(λ - ΣV)
This is the Rescorla-Wagner equation. It specifies that the amount of learning (the change ? in the predictive value of a stimulus V) depends on the amount of surprise (the difference between what actually happens, λ, and what you expect, ΣV). By convention, λ is usually set to a value of 1 when the US is present, and 0 when it is absent. A value other than 1 might be used if you want to model a larger or smaller US. The other two terms, α and β, relate to the salience of the CS and the speed of learning for a given US. According to Rescorla and Wagner, these parameters affect the rate of learning, but neither of them cha in most cases we can ignore α and β and focus solely on surprise to determine the extent to which learning will occur. For further information on the equation, see main article on the model.
The R–W model measures conditioning by assigning an "associative strength" to the CS. Before a CS is conditioned it has an associative strength of zero. Pairing the CS and the US causes a gradual increase in the associative strength of the CS. This increase is determined by the nature of the US (e.g. its intensity). The amount of learning that happens during any single CS-US pairing depends on the difference between the current associative strength of the CS and the maximum set by the US. On the first pairing of the CS and US, the difference is large and the associative strength of the CS takes a big step up. As CS-US pairings accumulate, the US becomes more predictable, and the increase in associative strength on each trial becomes smaller and smaller. Finally the difference between the associative strength of the CS and the maximum strength reaches zero. That is, the CS fully predicts the US, the associative strength of the CS stops growing, and conditioning is complete.
The associative process described by the R–W model also accounts for extinction (see "procedures" above). The extinction procedure starts with a positive associative strength of the CS, which means that the CS predicts that the US will occur. On an extinction trial the US fails to occur after the CS. As a result of this “surprising” outcome, the associative strength of the CS takes a step down. Extinction is complete when the strength of the CS no US is predicted, and no US occurs. However, if that same CS is presented without the US but accompanied by a well-established conditioned inhibitor (CI), that is, a stimulus that predicts the absence of a US (in R-W terms, a stimulus with a negative associate strength) then R-W predicts that the CS will not undergo extinction (its V will not decrease in size).
Main article:
The most important and novel contribution of the R–W model is its assumption that the conditioning of a CS depends not just on that CS alone, and its relationship to the US, but also on all other stimuli present in the conditioning situation. In particular, the model states that the US is predicted by the sum of the associative strengths of all stimuli present in the conditioning situation. Learning is controlled by the difference between this total associative strength and the strength supported by the US. When this sum of strengths reaches a maximum set by the US, conditioning ends as just described.
The R–W explanation of the blocking phenomenon illustrates one consequence of the assumption just stated. In blocking (see "phenomena" above), CS1 is paired with a US until conditioning is complete. Then on additional conditioning trials a second stimulus (CS2) appears together with CS1, and both are followed by the US. Finally CS2 is tested and shown to produce no response because learning about CS2 was “blocked” by the initial learning about CS1. The R–W model explains this by saying that after the initial conditioning, CS1 fully predicts the US. Since there is no difference between what is predicted and what happens, no new learning happens on the additional trials with CS1+CS2, hence CS2 later yields no response.
One of the main reasons for the importance of the R–W model is that it is relatively simple and makes clear predictions. Tests of these predictions have led to a number of important new findings and a considerably increased understanding of conditioning. Some new information has supported the theory, but much has not, and it is generally agreed that the theory is, at best, too simple. However, no single model seems to account for all the phenomena that experiments have produced. Following are brief summaries of some related theoretical issues.
The R–W model reduces conditioning to the association of a CS and US, and measures this with a single number, the associative strength of the CS. A number of experimental findings indicate that more is learned than this. Among these are two phenomena described earlier in this article
Latent inhibition: If a subject is repeatedly exposed to the CS before conditioning starts, then conditioning takes longer. The R–W model cannot explain this because preexposure leaves the strength of the CS unchanged at zero.
Recovery of responding after extinction: It appears that something remains after extinction has reduced associative strength to zero because several procedures cause responding to reappear without further conditioning.
Latent inhibition might happen because a subject stops focusing on a CS that is seen frequently before it is paired with a US. In fact, changes in attention to the CS are at the heart of two prominent theories that try to cope with experimental results that give the R–W model difficulty. In one of these, proposed by , the speed of conditioning depends on the amount of attention devoted to the CS, and this amount of attention depends in turn on how well the CS predicts the US. Pearce and Hall proposed a related model based on a different attentional principle Although neither model explains all conditioning phenomena, the attention idea still has an important place in conditioning theory.
As stated earlier, a key idea in conditioning is that the CS signals or predicts the US (see "zero contingency procedure" above). However, the room or chamber in which conditioning takes place, also “predicts” that the US may occur. Still, it usually predicts with much less certainty than does the experimental CS itself. The role of such context is illustrated by the fact that the dogs in Pavlov's experiment would sometimes start salivating as they approached the experimental apparatus, before they saw or heard any CS. Such so-called “context” stimul they have been found to play an important role in conditioning and they help to account for some otherwise puzzling experimental findings. Context plays an important role in the comparator and computational theories outlined below.
To find out what has been learned, we must somehow measure behavior ("performance") in a test situation. However, as students know all too well, performance in a test situation is not always a good measure of what has been learned. As for conditioning, there is evidence that subjects in a blocking experiment do learn something about the “blocked” CS, but fail to show this learning because of the way that they are usually tested.
“Comparator” theories of conditioning are “”, that is, they stress what is going on at the time of the test. In particular, they look at all the stimuli that are present during testing and at how the associations acquired by these stimuli may interact. To oversimplify somewhat, comparator theories assume that during conditioning the subject acquires both CS-US and context-US associations. At the time of the test, these associations are compared, and a response to the CS occurs only if the CS-US association is stronger than the context-US association. After a CS and US are repeatedly paired in simple acquisition, the CS-US association is strong and the context-US association is relatively weak. This means that the CS elicits a strong CR. In “zero contingency” (see above), the conditioned response is weak or absent because the context-US association is about as strong as the CS-US association. Blocking and other more subtle phenomena can also be explained by comparator theories, though, again, they cannot explain everything.
An organism's need to predict future events is central to modern theories of conditioning. Most theories use associations between stimuli to take care of these predictions. For example: In the R–W model, the associative strength of a CS tells us how strongly that CS predicts a US. A different approach to prediction is suggested by models such as that proposed by Gallistel & Gibbon (). Here the response is not determined by associative strengths. Instead, the organism records the times of onset and offset of CSs and USs and uses these to calculate the probability that the US will follow the CS. A number of experiments have shown that humans and animals can learn to time events (see ), and the Gallistel & Gibbon model yields very good quantitative fits to a variety of experimental data. However, recent studies have suggested that duration-based models cannot account for some empirical findings as well as associative models.
Pavlov proposed that conditioning involved a connection between brain centers for conditioned and unconditioned stimuli. His physiological account of conditioning has been abandoned, but classical conditioning continues to be studied in attempts to understand the neural structures and functions that underlie learning and memory. Forms of classical conditioning that are used for this purpose include, among others, , , and the foot contraction conditioning of , a sea-slug.
In their textbook on ,
and V. Tsyrkin list five criteria for demarcation between unconditioned and conditioned reflexes. Unlike conditioned reflexes, the unconditioned reflexes are mostly stable. As described above, the conditioned reflexes are not only unstable but can be modified and extinguished. These two distinctions between the reflexes can be seen under
A leading role in the performance of unconditioned reflexes is played by the lower divisions of the higher , the ,
and .:vol. II, p. 330 Conditioned reflexes, in contrast, are a function of the
and can involve the most varied stimuli applied to different .:see a table at page 105
Main article:
Some therapies associated with classical conditioning are ,
and . Aversion therapy is a type of behavior therapy designed to make patients give up an undesirable habit by causing them to associate it with an unpleasant effect. Systematic desensitization is a treatment for phobias in which the patient is trained to relax while being exposed to progressively more anxiety-provoking stimuli(e.g. angry words). Flooding attempts to eliminate an unwanted CR. This type of behavior therapy is a form of desensitization for treating phobias and anxieties by repeated exposure to highly distressing stimuli until the lack of reinforcement of the anxiety response causes its extinction. It is usually with actual exposure to the stimuli, with implosion used for imagined exposure, but the two terms are sometimes used synonymously. .
Conditioning therapies usually take less time than
therapies.
A stimulus that is present when a drug is administered or consumed may eventually evoke a conditioned physiological response that mimics the effect of the drug. This is sometimes th habitual coffee drinkers may find that the smell of coffee gives them a feeling of alertness. In other cases, the conditioned response is a compensatory reaction that tends to offset the effects of the drug. For example, if a drug causes the body to become less sensitive to pain, the compensatory conditioned reaction may be one that makes the user more sensitive to pain. This compensatory reaction may contribute to . If so, a drug user may increase the amount of drug consumed in order to feel its effects, and end up taking very large amounts of the drug. In this case a dangerous overdose reaction may occur if the CS happens to be absent, so that the conditioned compensatory effect fails to occur. For example, if the drug has always been administered in the same room, the stimuli provided by that room may produce a conditioned then an overdose reaction may happen if the drug is administered in a different location where the conditioned stimuli are absent.
Signals that consistently precede food intake can become conditioned stimuli for a set of bodily responses that prepares the body for food and digestion. These reflexive responses include the secretion of digestive juices into the stomach and the secretion of certain hormones into the blood stream, and they induce a state of hunger. An example of conditioned hunger is the "appetizer effect." Any signal that consistently precedes a meal, such as a clock indicating that it is time for dinner, can cause people to feel hungrier than before the signal. The lateral hypothalamus (LH) is involved in the initiation of eating. The nigrostriatal pathway, which includes the substantia nigra, the lateral hypothalamus, and the basal ganglia have been shown to be involved in hunger motivation.
Further information:
The influence of classical conditioning can be seen in emotional responses such as , disgust, nausea, anger, and sexual arousal. A familiar example is conditioned nausea, in which the CS is the sight or smell of a particular food that in the past has resulted in an unconditioned stomach upset. Similarly, when the CS is the sight of a dog and the US is the pain of being bitten, the result may be a conditioned fear of dogs.
As an adaptive mechanism, emotional conditioning helps shield an individual from harm or prepare it for important biological events such as sexual activity. Thus, a stimulus that has occurred before sexual interaction comes to cause sexual arousal, which prepares the individual for sexual contact. For example, sexual arousal has been conditioned in human subjects by pairing a stimulus like a picture of a jar of pennies with views of an erotic film clip. Similar experiments involving blue gourami fish and domesticated quail have shown that such conditioning can increase the number of offspring. These results suggest that conditioning techniques might help to increase fertility rates in infertile individuals and endangered species.
This article appears to contain
references to . Please
to explain the subject's impact on popular culture rather than simply
rather than deleting it if possible. (September 2014)
One of the earliest literary references to classical conditioning can be found in the comic novel
(1759) by . The narrator Tristram Shandy explains how his mother was conditioned by his father's habit of winding up a clock before having sex with her:
My father [...] was, I believe, one of the most regular men in everything he did [...] [H]e had made it a rule for many years of his life,—on the first Sunday-night of every month throughout the whole year,—as certain as ever the Sunday-night came,—to wind up a large house-clock, which we had standing on the back-stairs head, with his own hands:—And being somewhere between fifty and sixty years of age at the time I have been speaking of,—he had likewise gradually brought some other little family concernments to the same period, in order, as he would often say to my uncle Toby, to get them all out of the way at one time, and be no more plagued and pestered with them the rest of the month. [...]
[F]rom an unhappy association of ideas, which have no connection in nature, it fell out at length, that my poor mother could never hear the said clock wound up,—but the thoughts of some other things unavoidably popped into her head—& vice versa:—Which strange combination of ideas, the sagacious Locke, who certainly understood the nature of these things better than most men, affirms to have produced more wry actions than all other sources of prejudice whatsoever.
In the 1932 novel , written by , conditioning plays a key role in the maintenance of social peace, especially in maintaining the
upon which society is based. Children are conditioned, both in their sleep and in their daily activities. They're conditioned to be happy in their government-assigned social role as "Alphas", "Betas", and so on, as well as in adopting other "socially acceptable" types of behaviour, including consuming manufactured goods and transport, practicing free sex, etc. For example, earlier in the book, the director of the Central London Hatchery and Conditioning Centre shows his young visitors how a group of toddlers of the Delta caste is conditioned to avoid books and flowers, by using shrill noises to terrorise them and applying "mild electric shocks". Also, in a later explanation by Resident World Controller of Western Europe, Mustapha Mond, of how their society really works, he explains how early conditioning is an essential part of how social harmony among the different castes is maintained. Lower-caste members like Epsilons are as happy as upper-caste Alpha-Pluses, in large part due to their conditioning.
Another example is in the 1962 dystopian novel
in which the novel's
and , Alex, undergoes a procedure called the , where he is fed a solution to cause severe nausea and then forced to watch violent acts. This renders him unable to perform any violent acts without inducing similar nausea. Unintentionally, he also forms an aversion to classical music.
In the 1999 science-fiction novel
"Pavlovian mental bans" are used to prevent crime. In the book a controversial scientist, Anton, is kept from researching genetic experimentation by associating his work with anxiety. A device is then surgically placed in his head that would increase detected anxiety, sending him into a . The result is that Anton must remain good-humored at all times, can only speak of his work through self-deceptive metaphors, and even after his Pavlovian mental ban is lifted can no longer study science. An abusive father is also mentioned to have he proceeds to become pleasant for a time, before eventually committing suicide.
In the "" episode of 's TV series , Jim conditions Dwight to want a
whenever he hears a .[]
          
Cherry, Kendra. . < Guide. .
Shettleworth, Sara J.(2010) Cognition, Evolution, and Behavior (2nd edn) Oxford Univ. Press
Rescorla, Robert A. . (1988) American Psychologist, 43, 151-160.
Bouton, M. E. (2007) Learning and Behavior: A Contemporary Synthesis, Sunderland, MA: Sinauer
Pavlov, I. P. (). Conditional Reflexes. New York: Dover Publications (the 1960 edition is not an unaltered republication of the 1927 translation by Oxford University Press ).
Douglas L. Medin, Brian H. Ross, and Arthur B. Markman. Cognitive Psychology. N.p.:n.p,2009. Print 50-53
T.L. Brink (2008) Psychology: A Student Friendly Approach.
pp.&#160;97–98
Chang, Raymond C.; Stout,S Miller, Ralph R. "Comparing excitatory backward and forward conditioning." Quarterly Journal of Experimental Psychology: Section B January 2004. Vol. 57 Issue 1, pp. 1-23. State University of New York at Binghamton, New York, USA.
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print. 69
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print. pp.66
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print. pp.71
Rescorla, R. A. (1967). . Psychological Review, 74, 71-80
Schacter, Daniel L (2009). PSYCHOLOGY. Catherine Woods. p.&#160;267. &#160;.
Shettleworth, S. J. (2010) Cognition, Evolution and Behavior (2nd Ed), New York: Oxford.
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print. pp. 84
Rescorla, R. A. & A. R. Wagner (1972). A theory of Pavlovan conditioning: Variations in the effectiveness of reinforcement and nonreinforcement. In Classical Conditioning II: Current Theory and Research Black & Prokasy (eds), p. 64-99. New York: Appleton-Century.
Miller, R. & M. Escobar Learning: Laws and Models of Basic Conditioning. In Stevens’ Handbook of Experimental Psychology,(3rd Edition) Vol 3: Learning, Motivation & Emotion, Pashler & Gallistel, (eds) pp 47-102 New York: Wiley
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print. pp. 85
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print pp 85-89
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print. pp. 85-89
Miller, R. R., Barnet, R. C. & Grahame, N. J. (1995) Assessment of the Rescorla–Wagner model. Psychological Bulletin, 117, 363-386
Mackintosh, N. J. (1975) A theory of attention: Variations in the associability of stimuli with reinforcement Psychological Review, 82, 276-298
Pearce, J. M. & Hall, G. (1980) . Psychological Review, 87, 532-552.
Gibbon, J. & Balsam P. (1981) Spreading association in time. In Locurto, Terrace & Gibbon (Eds.), Autoshaping and conditioning theory (pp. 219-235). New York: Academic Press
Miller, R. R. & Escobar, M. (2001) . Current Directions in Psychological Science 10, 141-145.
Gallistel, R. & Gibbon, J. (2000). . Psychological Review, 107, 289-304.
Gallistel, R. & Gibbon, J. (2002) The Symbolic Foundations of Conditioned Behavior. Mahwah, NJ: Erlbaum
Golkar, A., Bellander, M., & ?hman, A. (2013). Temporal properties of fear extinction--does time matter? "Behavioral neuroscience", 127(1), 59–69.
(1989). "Conditioned-Reflex Activity of the Cerebral Cortex". In . Human Physiology, in 2 vols. Translated by Ludmila A translation edited by H. C. Creighton (M.A., ). : . &#160;&#160;&#160;First published in Russian as <>
For more details, see: Физиология человека (Human Physiology, in Russian) // Под ред.
и В.И.Циркина. — СПб., 1998.
Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp.336
Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp136
Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp133
McGee, Donald Loring. Behavior Modification. , Inc. 2006. Retrieved on .
Carlson, Neil R. (2010). Psychology: The Science of Behaviour. New Jersey, United States: Pearson Education Inc. pp.&#160;599–604. &#160;.
Carlson, Neil R. (2010). Psychology: The Science of Behaviour. New Jersey, United States: Pearson Education Inc. pp.&#160;198–203. &#160;.
Laurence Sterne: The Life and Opinions of Tristram Shandy, Gentleman; Vol. 1, Chapter 1. IV
Further reading
(1989). "Chapter 17, the section “Conditioned-Reflex Activity of the Cerebral Cortex”". In . Human Physiology, in 2 vols. 2. Translated by Ludmila A translation edited by H. C. Creighton (M.A., ). : . pp.&#160;330–357. &#160;&#160;&#160;First published in Russian as <>
Dayan, P.; Kakade, S. & Montague, P.R. (2000). Learning and selective attention. Nature Neuroscience, 3, 1218–23.
Jami, S.A.; Wright, W.G. & Glanzman, D.L. (2007). . The Journal of Neuroscience, 27, 3064–8.
Kirsch, I.; Lynn, S.J.; Vigorito, M. & Miller, R.R. (2004). The role of cognition in classical and operant conditioning. , 60, 369–92.
Pavlov, I.P. (1927). : An Investigation of the Physiological Activity of the Cerebral Cortex (translated by ). London: Oxford University Press.
Rescorla, R.A. & Wagner, A.R. (1972). A theory of Pavlovian conditioning. Variations in effectiveness of reinforcement and non-reinforcement. In A. Black & W.F. Prokasky, Jr. (eds.), Classical Conditioning II New York: Appleton-Century-Crofts.
Schmidt, R. F. (1989). "Behavior Memory (Learning by Conditioning)". I . Human Physiology. Translated by Marguerite A. Biederman-Thorson (Second, completely revised ed.). Berlin etc.: . pp.&#160;155–156. &#160;.
Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, , 2008. Print.
Douglas L. Medin, Brian H. Ross, and Arthur B. Markman. Cognitive Psychology. N.p.:n.p,2009. Print
Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print.
: Hidden categories:}