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'''Classical conditioning''' (also '''Pavlovian conditioning''' or '''respondent conditioning''') is a type of associative [[learning]] found in animals. These associations are formed by pairing two [[stimulus|stimuli]]--what [[Ivan Pavlov]] described as the learning of conditioned [[behavior]]-- to [[conditioning|condition]] an animal to give a certain response. The simplest form of classical conditioning is reminiscent of what [[Aristotle]] would have called the law of contiguity which states that: "When two things commonly occur together, the appearance of one will bring the other to mind."
 
   
==Overview==
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'''Classical conditioning''' (also '''Pavlovian conditioning''' or '''respondent conditioning''') is a kind of learning that occurs when a conditioned stimulus (CS) is paired with an unconditioned stimulus (US). Usually, the CS is a neutral stimulus (e.g., the sound of a tuning fork), the US is biologically potent (e.g., the taste of food) and the unconditioned response (UR) to the US 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 CS when the CS is presented alone.  The CR is usually similar to the UR (see below), but unlike the UR, it must be acquired through experience and is relatively impermanent.<ref>{{cite web |url= http://psychology.about.com/od/cindex/g/condresp.htm |title= What Is a Conditioned Response? |first= Kendra |last= Cherry |work= About.com Guide |publisher= [[About.com]] |location= |accessdate= 2013-02-10 }}</ref>
The typical paradigm for classical conditioning involves repeatedly pairing a neutral stimulus with an unconditioned stimulus.
 
   
An '''[[unconditioned stimulus]]''' is a stimulus that elicits a response--known as an '''unconditioned response'''--that does not need to be learned by the animal. The relationship between the unconditioned stimulus and unconditioned response is known as the unconditioned (or unconditional) [[reflex]].
 
   
The '''[[conditioned stimulus]]''', or conditional stimulus, is an initially neutral stimulus that elicits a response--known as a '''conditioned response'''--that is learned by the animal. Conditioned stimuli are associated [[psychology|psychologically]] with conditions such as anticipation, satisfaction (both immediate and prolonged), and [[fear]]. The relationship between the conditioned stimulus and conditioned reponse is known as the conditioned (or conditional) reflex.
 
   
In classical conditioning, when the unconditioned stimulus is repeatedly or strongly paired with a neutral stimulus the neutral stimulus becomes a conditioned stimulus and elicits a conditioned response.
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Classical conditioning differs from [[Operant conditioning|''operant'' or ''instrumental'' conditioning]], in which a behavior is strengthened or weakened, depending on its consequences (i.e., reward or punishment).<ref name = "Bouton">Bouton, M. E. (2007) ''Learning and Behavior: A Contemporary Synthesis'', Sunderland, MA: Sinauer</ref>
   
To put it another way:
 
   
The typical procedure for inducing classical conditioning involves presentations of a neutral [[stimulus (physiology)|stimulus]] along with a stimulus of some significance. The neutral stimulus could be any event that does not result in an overt behavioral response from the organism under investigation. Pavlov referred to this as a ''[[Conditioned Stimulus]] (CS)''. Conversely, presentation of the significant stimulus necessarily evokes an innate, often reflexive, response. Pavlov called these the ''[[Unconditioned Stimulus]] (US)'' and ''[[Unconditioned Response]] (UR)'', respectively. If the CS and the US are repeatedly paired, eventually the two stimuli become associated and the organism begins to produce a behavioral response to the CS. Pavlov called this the ''Conditioned Response (CR)''.
 
   
Classical conditioning has been demonstrated in numerous species using a variety of methodologies.
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A classic experiment by [[Ivan Pavlov|Pavlov]] exemplifies the standard procedure used in classical conditioning.<ref name = "Pavlov">Pavlov, I. P. (1927/1960). ''Conditional Reflexes''. New York: Dover Publications (the 1960 edition is not an unaltered republication of the 1927 translation by Oxford University Press http://psychclassics.yorku.ca/Pavlov/).</ref> First Pavlov observed the UR (salivation) produced when meat powder (US) was placed in the dog's mouth. He then rang a bell (CS) before giving the meat powder. After some repetitions of this pairing of bell and meat the dog salivated to the bell alone, demonstrating what Pavlov called a "conditional" response, now commonly termed "conditioned response" or CR. 
   
Popular forms of classical conditioning that are used to study neural structures and functions that underlie learning and memory include [[fear conditioning]], [[eyeblink conditioning]], and classical conditioning of [[Aplysia gill and siphon withdrawal reflex]].
 
   
==History==
 
===Pavlov's experiment===
 
[[Image:One of Pavlov's dogs.jpg|thumb|250px|right|One of Pavlov’s dogs with a surgically implanted [[cannula]] to measure [[salivation]], Pavlov Museum, 2005]]
 
The original and most famous example of classical conditioning involved the [[saliva]]ry conditioning of Pavlov's dogs. During his research on the physiology of digestion in dogs, Pavlov noticed that, rather than simply salivating in the presence of meat powder (an innate response to food that he called the '''unconditioned response'''), the dogs began to salivate in the presence of the lab technician who normally fed them. Pavlov called these ''psychic secretions''. From this observation he predicted that, if a particular stimulus in the dog’s surroundings was present when the dog was presented with meat powder, then this stimulus would become ''associated'' with food and cause salivation on its own. In his initial experiment, Pavlov used bells to call the dogs to their food and, after a few repetitions, the dogs started to salivate in response to the bell. Thus, a neutral stimulus (bell) became a '''conditioned stimulus''' (CS) as a result of consistent pairing with the '''unconditioned stimulus''' (US - meat powder in this example). Pavlov referred to this learned relationship as a conditional reflex (now called '''Conditioned Response''').
 
   
==Types of Classical Conditioning==
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In conditioning the CS is not simply connected to UR. For example, the CR usually differs in some way from the UR; sometimes it is a lot different. For this and other reasons, learning theorists commonly suggest that the CS comes to signal or predict the US, and go on to analyze the consequences of this signal.<ref name="Shet">Shettleworth, Sara J.(2010) ''Cognition, Evolution, and Behavior (2nd edn)'' Oxford Univ. Press</ref> [[Robert A. Rescorla]] 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."<ref name=Rescorla1988>Rescorla, Robert A. [http://www.stanford.edu/class/psych227/RESCORLA%20(1988).pdf Pavlovian Conditioning &mdash; It's Not What You Think It Is]. (1988) American Psychologist, 43, 151-160.</ref>
   
Types and variations of classical conditioning are all derived from the same source. <ref>D.G. Lavond and J.E. Steinmetz (2003): Handbook of Classical Conditioning. Kluwer Academic Publishers, Boston, USA pp 9-13.</ref>
 
   
===Forward Conditioning===
 
   
The onset of the CS precedes the onset of the US. Three common forms of Forward Conditioning are: Short-delay, Long-delay, and Trace.
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==Procedures==
   
:'''Short-delay Conditioning'''
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[[Ivan Pavlov]] provided the most famous example of classical conditioning, although [[Edwin Twitmyer]] published his findings a year earlier (a case of simultaneous discovery).<ref name = "Pavlov"/>   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 then gave the dog food; 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.<ref>Douglas L. Medin, Brian H. Ross, and Arthur B. Markman. Cognitive Psychology. N.p.:n.p,2009. Print 50-53</ref> 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.<ref>T.L. Brink (2008) Psychology: A Student Friendly Approach. [http://www.saylor.org/site/wp-content/uploads/2011/01/TLBrink_PSYCH06.pdf "Unit 6: Learning."] pp.&nbsp;97–98 </ref>
   
:The onset of the US is ''delayed'' relative to the onset of the CS. In this procedure, the CS may completely overlap with the US, or the CS may terminate at some point before the US offset. The term "short" refers to the [[interstimulus interval]] (ISI), and is determined by the type of classical conditioning. For example, in some forms of classical conditioning, such as [[eyeblink conditioning]], ISIs in the range of 100 to 750 msec are typically considered short. In other forms of classical conditioning, such as in [[taste aversion]], ISIs in the range of minutes to 1 or 2 hours are considered short.
 
   
:'''Long-delay Conditioning'''
 
   
:In this procedure, the onset of the US is still delayed relative to the onset of the CS, but ISIs are longer than in the Short-delay Procedure. While the difference between Short and Long may appear trivial, the distinction is important because some forms of conditioning are best learned with a long delay, while others are best learned with a short delay.
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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.<ref name= "Bouton"/><ref name=Rescorla1988/> 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. 
   
:'''Trace Conditioning'''
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[[Image:delay,trace conditioning.svg|thumb|right|384px|Diagram representing forward conditioning. The time interval increases from left to right.]]
   
:The CS and US do not overlap. Instead, the CS is presented, a period of time is allowed to elapse during which no stimuli are presented, and then the US is presented. The stimulus free period is called the ''trace interval''.
 
   
===Simultaneous Conditioning===
 
   
The CS and US are presented at the same time.
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===Forward conditioning===
   
===Backward Conditioning===
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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.<ref name="Chang">Chang, Raymond C.; Stout,Steven; 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.</ref><ref>Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. 69</ref> Two common forms of forward conditioning are delay and trace conditioning.
{{mainarticle|backward conditioning}}
 
The onset of the US precedes the onset of the CS. Rather than being a reliable predictor of an impending US (such as in Forward Conditioning), the CS actually serves as a signal that the US has ended. As a result, the CR is said to be ''inhibitory''.
 
   
===Temporal Conditioning===
 
   
The US is presented at regularly timed intervals, and CR acquisition is dependent upon correct timing of the interval between US presentations. The background, or context, can serve as the CS in this example.
 
   
===Unpaired Conditioning===
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*'''Delay conditioning''': In delay conditioning the CS is presented and is overlapped by the presentation of the US.
   
The CS and US are not presented together. Usually they are presented as independent trials that are separated by a variable, or pseudo-random, interval. This procedure is used to study non-associative behavioral responses, such as [[sensitization]].
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*'''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.''
   
===CS-Alone Extinction===
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The difference between trace conditioning and delay conditioning is that in the delayed procedure the CS and US overlap.
   
The CS is presented in the absence of the US. This procedure is usually done after the CR has been acquired through Forward Conditioning training. Eventually, the CR frequency is reduced to pre-training levels.
 
   
==Variations of Classical Conditioning Procedures==
 
   
In addition to the simple procedures described above, some classical conditioning studies are designed to tap into more complex learning processes. Some common variations are discussed below.
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[[File:Forward Conditioning.svg]]
   
===Classical Discrimination/Reversal Conditioning===
 
   
In this procedure, two CSs and one US are typically used. The CSs may be the same modality (such as lights of different intensity), or they may be different modalities (such as auditory CS and visual CS). In this procedure, one of the CSs is designated CS+ and its presentation is always followed by the US. The other CS is designated CS- and its presentation is never followed by the US. After a number of trials, the organism learns to ''discriminate'' CS+ trials and CS- trials such that CRs are only observed on CS+ trials.
 
   
During ''Reversal Training'', the CS+ and CS- are reversed and subjects learn to suppress responding to the previous CS+ and show CRs to the previous CS-.
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===Simultaneous conditioning===
   
===Classical ISI Discrimination Conditioning===
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[[File:Classical Conditioning.svg|thumb|Classical conditioning procedures and effects]]
   
This is a discrimination procedure in which two different CSs are used to signal two different [[interstimulus interval]]s. For example, a dim light may be presented 30 seconds before a US, while a very bright light is presented 2 minutes before the US. Using this technique, organisms can learn to perform CRs that are appropriately timed for the two distinct CSs.
 
   
===Latent Inhibition Conditioning===
 
   
In this procedure, a CS is presented several times before paired CS-US training commences. The pre-exposure of the subject to the CS before paired training slows the rate of CR acquisition relative to organisms that are not CS pre-exposed. Also see [[Latent inhibition]] for applications.
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During simultaneous conditioning, the CS and US are presented and terminated at the same time.
   
===Conditioned Inhibition Conditioning===
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''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.''
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[[File:Simultaneous Conditioning.svg]]
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===Second-order and higher-order conditioning===
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{{main|Second-order conditioning}}
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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.<ref>Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp.66</ref> 
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''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''
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[[File:Second Order Conditioning.svg]]
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===Backward conditioning===
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Backward conditioning occurs when a CS immediately follows a US.<ref name="Chang"/> 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.<ref>Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp.71</ref> ''For example, a puff of air directed at a person's eye could be followed by the sound of a buzzer.''
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===Temporal conditioning===
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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 [[Animal cognition]]).
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[[File:Temporal Conditioning.svg]]
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===Zero contingency procedure===
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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.<ref>Rescorla, R. A. (1967). [http://www.uk.sagepub.com/upm-data/23600_Ch_1.pdf Pavlovian conditioning and its proper control procedures].  ''Psychological Review'', 74, 71-80</ref> This finding -  that ''prediction'' rather than CS-US pairing is the key to conditioning - greatly influenced subsequent conditioning research and theory.
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===Extinction===
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{{main|Extinction (psychology)}}    
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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.
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==Phenomena observed==
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===Acquisition===
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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<ref name="Bouton"/><ref name="Shet"/> 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.<ref name="Schacter 2009 267">{{cite book|last=Schacter|first=Daniel L|title=PSYCHOLOGY|year=2009|publisher=Catherine Woods|isbn=978-1-4292-3719-2|pages=267}}</ref>
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===Extinction===
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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".<ref name = Shet/>
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[[File:Classical conditioning - extinction.svg]]
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===External inhibition===
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[[External inhibition]] 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.
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===Recovery from extinction===
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Several procedures lead to the recovery of an extinguished CR. The following examples assume that the CS has been 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 <ref name = "Bouton"/>
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*Reacquisition:
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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. 
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*Spontaneous recovery:
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{{main|Spontaneous recovery (psychology)}}
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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.
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*External inhibition:
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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
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*Reinstatement:
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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. 
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*Renewal:
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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.
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===Stimulus generalization===
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''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.<ref name = Shet/> The more the test stimulus differs from the CS the more the conditioned response will differ from that previously observed. Appercepting more stimuli from  the environment will cause the more widely spreadout CR in the brain cellular network, that is called  GENERALIZED. WIth more in-phased braincells in chain the complete brain will show a significant reaction with the generalization on almost any CS stimulus in apperception.<ref>{{cite book|last=Schacter|first=Daniel L|title=PSYCHOLOGY|year=2009|publisher=Catherine Woods|isbn=978-1-4292-3719-2|pages=269}}</ref>
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===Stimulus discrimination===
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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.<ref name = Shet/>
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===Latent inhibition===
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{{main|Latent inhibition}}
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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.<ref name = Shet/>
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===Conditioned suppression===
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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 [[operant conditioning]].  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 classical conditioning; 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.)
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===Conditioned inhibition===
   
 
Three phases of conditioning are typically used:
 
Three phases of conditioning are typically used:
   
:'''Phase 1:'''
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;Phase 1
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:A CS (CS+) is paired with a US until asymptotic CR levels are reached.
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;Phase 2
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: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.
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::A CS (CS+) is paired with a US until asymptotic CR levels are reached.
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;Phase 3
   
:'''Phase 2:'''
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*''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.
   
::CS+/US trials are continued, but interspersed with trials on which the CS+ in compound with a second CS, but not with the US (i.e., CS+/CS- trials). Typically, organisms show CRs on CS+/US trials, but suppress responding on CS+/CS- trials.
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*''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.
   
:'''Phase 3:'''
 
   
::In this retention test, the previous CS- is paired with the US. If conditioned inhibition has occurred, the rate of acquisition to the previous CS- should be impaired relative to organisms that did not experience Phase 2.
 
   
 
===Blocking===
 
===Blocking===
{{mainarticle|Blocking effect}}
 
This form of classical conditioning also involves three phases.
 
   
:'''Phase 1:'''
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{{main|Blocking effect}}
   
::A CS (CS1) is paired with a US.
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This form of classical conditioning involves two phases.
   
:'''Phase 2:'''
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;Phase 1
   
::CS1 is presented in compound with a new CS (CS2), and the compound is paired with the US.
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:A CS (CS1) is paired with a US.
   
:'''Phase 3:'''
 
   
::CS2 is paired with the US. Blocking is measured as impairment in the rate of learning to CS2 relative to organisms that did not experience Phase 2. Essentially, acquisition to CS2 is blocked during compound training because CRs had already formed to CS1.
 
   
==Classical Conditioning Applied==
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;Phase 2
   
===John B. Watson's Little Albert===
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:A compound CS (CS1+CS2) is paired with a US.
{{mainarticle|Little Albert experiment}}
 
   
[[John B. Watson]] is the founder of behaviourism (1913).He is the also known as father of modern psychology.Gives the definition of modern psychology in 1913 i.e SCIENCE OF BEHAVIOUR
 
   
BEHAVIOUR
 
1.overt
 
2. covert
 
According to Watson, only things that are included in the subject matter of psychology can be measured like behaviour.
 
His first experiment was performed on an infant by the name of Albert in 1919.
 
   
===Behavioral Therapies Based on Classical Conditioning===
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;Test
{{mainarticle|Behaviour therapy}}
 
In [[human]] psychology, implications for therapies and treatments using classical conditioning differ from [[operant conditioning]]. Therapies associated with classical conditioning are [[aversion therapy]], [[flooding (psychology)|flooding]], [[systematic desensitization]], and implosion therapy.
 
   
Classical conditioning is short-term, usually requiring less time with therapists and less effort from patients, unlike [[humanistic psychology|humanistic]] therapies.{{Fact|date=January 2008}} The therapies mentioned in the last paragraph are intended to cause either aversive feelings toward something, or to reduce the aversion altogether. Classical conditioning is based on a repetitive behaviour system.
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: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.
   
====Aversion therapy====
 
{{mainarticle|Aversion therapy}}
 
Aversion therapy is a form of psychological therapy that is designed to eliminate, for example, [[human sexuality|sexual]] behaviour by associating an aversive stimulus such as [[nausea]] with sex. Because the aversive stimulus performs as a US and produces a UR, the association between the stimulus and behaviour leads to the same consequences each time. If the treatment has worked, the patient will not have a compulsion to engage in such behaviours again.{{Fact|date=January 2008}} This sort of treatment has been used to treat [[alcoholism]] as well as [[drug addiction]].{{Fact|date=January 2008}}
 
   
====Systematic desensitization====
 
{{mainarticle|Systematic desensitization}}
 
Patients might learn that the object of their [[phobia]]s or fears are not so fearful if they can safely relive the feared stimulus. However, anxiety often obstructs such recovery. This obstruction is overcome by reintroducing the fear-producing object gradually by a process known as reciprocal inhibitions. A person constructs a hierarchy of events leading to the feared situation. This hierarchy is approached step by step and anxiety is relieved at every level. The fear is eventually removed if the therapy is performed correctly.{{Fact|date=January 2008}}
 
   
==Theories of classical conditioning==
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[[File:Classical conditioning - blocking.svg]]
There are two competing theories of how classical conditioning works. The first, stimulus-response theory, suggests that an association to the unconditioned stimulus is made with the conditioned stimulus within the brain, but without involving conscious thought. The second theory stimulus-stimulus theory involves cognitive activity, in which the conditioned stimulus is associated to the concept of the unconditioned stimulus, a subtle but important distinction.
 
   
'''Stimulus-response theory''', referred to as S-R theory, is a theoretical model of behavioral psychology that suggests humans and other animals can learn to associate a new stimulus- the conditioned stimulus (CS)- with a pre-existing stimulus - the unconditioned stimulus (UCS), and can think, feel or respond to the CS as if it were actually the UCS.
 
   
The opposing theory, put forward by cognitive behaviorists, is stimulus-stimulus theory (S-S theory). '''Stimulus-stimulus theory''', referred to as S-S theory, is a theoretical model of classical conditioning that suggests a cognitive component is required to understand classical conditioning and that stimulus-response theory is an inadequate model. It proposes that a cognitive component is at play. S-R theory suggests that an animal can learn to associate a conditioned stimulus (CS) such as a bell, with the impending arrival of food termed the unconditioned stimulus, resulting in an observable behavior such as salivation. Stimulus-stimulus theory suggests that instead the animal salivates to the bell because it is associated with the concept of food, which is a very fine but important distinction.
 
   
To test this theory, psychologist Robert Rescorla undertook the following experiment <ref>Rescorla, R (1973) Effect of US habituation following conditioning. ''Journal of Comparative and Physiological Psychology, 82 17-143''</ref>. Rats learned to associate a loud noise as the unconditioned stimulus, and a light as the conditioned stimulus. The response of the rats was to freeze and cease movement. What would happen then if the rats were [[habituation|habituated]] to the UCS? S-R theory would suggest that the rats would continue to respond to the UCS, but if S-S theory is correct, they would be habituated to the concept of a loud sound (danger), and so would not freeze to the CS. The experimental results suggest that S-S was correct, as the rats no longer froze when exposed to the signal light. <ref>Psychology, Peter Gray ''Third Edition'' pg 121</ref>
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==Theories==
   
   
==Behavioral therapies based on classical conditioning==
 
In [[human]] psychology, implications for therapies and treatments using classical conditioning differ from [[operant conditioning]]. Therapies associated with classical conditioning are [[aversion therapy]], flooding, [[systematic desensitization]], and implosion therapy. Implosion therapy and "flooding" involve forcing the individual to face an object/situation giving rise to [[anxiety]]; both of these techniques have been criticized for being [[ethics|unethical]] since they have the potential to cause trauma.
 
   
Classical conditioning is short-term, usually requiring less time with therapists and less effort from patients, unlike [[humanistic]] therapies. The therapies mentioned in the last paragraph are intended to cause either aversive feelings toward something, or to reduce the aversion altogether. Classical conditioning is based on a repetitive behaviour system.
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===Data sources===
   
===Aversion therapy===
 
This is a form of psychological therapy that is designed to eliminate [[human sexuality|sexual]] behaviour by associating an aversive stimulus such as [[nausea]] with sex. Because the aversive stimulus performs as a UCS and produces a UCR, the association between the stimulus and behaviour leads to the same consequences each time. If the treatment has worked, the patient will not have a complusion to engage in such behaviours again. This sort of treatment has been used to treat [[alcoholism]] and [[drug addiction]] as well as--controversially--[[homosexuality]] and sexual perversions. Adams ''et al.'' (1981), states that these controversial treatments involved administering electric shocks to homosexuals to reduce the response to male nudes, and encouraging a [[heterosexuality|heterosexual]] response to female nudes.
 
   
===Systematic desensitization===
 
Patients might learn that the object of their [[phobia]]s or fears are not so fearful if they can safely relive the feared stimulus. However anxiety often obstructs such recovery. This obstruction is overcome by reintroducing the fear-producing object gradually. A person imagines a series of advancing fearful situations while the person is languid. The responses of irrational fear to the object are eventually rendered incompatible--known as reciprocal inhibition--and the fear is eventually removed if the therapy is performed correctly.
 
   
==Neural structures involved in classical conditioning==
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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''.<ref>Shettleworth, S. J. (2010) Cognition, Evolution and Behavior (2nd Ed), New York: Oxford.</ref>  Most relevant experiments have used the classical conditioning procedure, although [[Operant conditioning|instrumental (operant) conditioning]] 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  [[Shaping (psychology)|autoshaping]] .
{{Expert-subject|Neuroscience}}
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[[Dopamine]] neurons in the pars compacta of substantia nigra and the medially adjoining ventral tegmental area show short, phasic activations after presentation of appetitive US. These phasic dopamine responses transfer to the onset of conditioned stimuli.<ref>W. Schultz Multiple reward signals in the brain. Nature Reviews Neuroscience 1:199-207, 2000</ref>
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It has been suggested that the ventral [[striatum]] corresponds to the critic and responds during both Pavlovian and [[instrumental conditioning]] and the dorsal striatum corresponds to the actor which mainly responds during [[operant conditioning]].<ref>J.P. O'Doherty et al., Dissociable Roles of Ventral and Dorsal [[Striatum]] in [[Instrumental Conditioning]]. Science 304:452-454, 2004 </ref>[[Amygdala]] has long been associated with Pavlovian [[fear conditioning]], but recent views suggest that amygdala also responds to appetitive stimuli.<ref>J. J. Paton et al. The primate amygdala represents the positive and negative value of visual stimuli during learning. Nature 439:865–870, 2006</ref> Neurons within the [[orbitofrontal cortex]] discriminate between visual stimuli that predict appetitive and aversive reinforcers <ref> J. O'Doherty et al. Abstract reward and punishment representations in the human orbitofrontal cortex. Nature Neuroscience 4:95-102,2001</ref> The [[cerebellum]] also appears to be involved in classical conditioning. Researchers demonstrated that lesions to pathways from the cerebellum stop the conditioned response, but do not stop the unconditioned response.<ref>R.F. Thompson: The neurobiology of learning and memory. Science 233:941-947, 1986</ref>
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===Stimulus-substitution theory===
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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.<ref>Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp. 84</ref> 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.
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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.
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It has been proposed that only when the UR does not involve the central nervous system are the CR and the UR opposites.
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===The Rescorla–Wagner model===
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{{main|Rescorla–Wagner model}}
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The Rescorla–Wagner (R–W) model<ref name="Bouton"/><ref>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.</ref>  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.<ref name = "M&E">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</ref><ref>Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp. 85</ref>
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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.
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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.
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==== The equation ====
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 ∆V= αβ(λ − ΣV)
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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.<ref>Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print pp 85-89</ref> 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 changes during learning; 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.
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====R–W model:  acquisition ====
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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).<ref name="Chance, Paul 2008. pp. 85-89">Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp. 85-89</ref> 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.
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====R–W model: extinction====
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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 reaches zero; 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).
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====R–W model: blocking====
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{{main|Blocking effect}}
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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.<ref name="Chance, Paul 2008. pp. 85-89"/>
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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.
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===Theoretical issues and alternatives to the Rescorla–Wagner model===
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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.<ref name = "Bouton"/><ref>Miller, R. R., Barnet, R. C. & Grahame, N. J. (1995) Assessment of the Rescorla–Wagner model.  ''Psychological Bulletin'', 117, 363-386</ref>   Following are brief summaries of some related theoretical issues.<ref name="M&E"/>
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====The content of learning====
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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
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*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.
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*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.<ref name = "Bouton"/>
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====The role of attention in learning====
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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 [[Nicholas Mackintosh]],<ref>Mackintosh, N. J. (1975) A theory of attention: Variations in the associability of stimuli with reinforcement  ''Psychological Review'', 82, 276-298</ref> 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<ref>Pearce, J. M. & Hall, G. (1980) [http://webdocs.cs.ualberta.ca/~elliot/PearceHall1980_PsychReview.pdf A model for Pavlovian learning: Variations in the effectiveness of conditioned but not of unconditioned stimuli]. ''Psychological Review'', 87, 532-552.</ref>  Although neither model explains all conditioning phenomena, the attention idea still has an important place in conditioning theory.<ref name = "Bouton"/>
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====Context====
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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.<ref name="Schacter 2009 267"/> Such so-called “context” stimuli are always present;  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.<ref name = "Bouton"/>
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====Comparator theory====
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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.
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“Comparator” theories of conditioning are “performance based;”, 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.<ref>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</ref><ref>Miller, R. R. & Escobar, M. (2001) [http://faculty.oxy.edu/clint/learn/articles/contrastingacquisitionfocusedandperformancefocusedmodelsofacquiredbehavior.pdf Contrasting acquisition-focused and performance-focused models of acquired behavior]. ''Current Directions in Psychological Science'' 10, 141-145.</ref>  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.<ref name="Bouton"/><ref name="M&E"/>
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====Computational theory====
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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 (2000, 2002).<ref>Gallistel, R. & Gibbon, J. (2000). [http://ruccs.rutgers.edu/faculty/GnG/Gal&Gib_Preprint.pdf Time, rate and conditioning]. ''Psychological Review'', 107, 289-304.</ref><ref>Gallistel, R. & Gibbon, J. (2002) ''The Symbolic Foundations of Conditioned Behavior''. Mahwah, NJ: Erlbaum</ref> 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 [[Animal cognition]]), and the Gallistel & Gibbon model yields very good quantitative fits to a variety of experimental data.<ref name = "Shet"/><ref name="M&E"/> However, recent studies have suggested that duration-based models cannot account for some empirical findings as well as associative models.<ref>Golkar, A., Bellander, M., & Öhman, A. (2013). Temporal properties of fear extinction--does time matter? "Behavioral neuroscience", 127(1), 59–69.</ref>
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==Applications==
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===Neural basis of learning and memory===
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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, [[fear conditioning]], [[eyeblink conditioning]], and the foot contraction conditioning of ''[[Hermissenda crassicornis]]'', a sea-slug.
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In their textbook on [[human physiology]], [[:ru:Агаджанян, Николай Александрович|Nikolai Agajanyan]] 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 the neural processes;  A leading role in the performance of unconditioned reflexes is played by the lower divisions of the higher [[Central nervous system|nervous system]], the [[Cerebral cortex|subcortical nuclei]], [[brain stem]] and [[spinal cord]].<ref>{{cite book
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| last       = Babsky
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| first      = Evgeni
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| authorlink = Evgeni Babsky
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| coauthors  = [[Boris Khodorov]], [[Grigory Kositsky]], [[Anatoly Zubkov]]
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| editor        = 
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| editor-last  = Babsky
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| editor-first = Evgeni
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| editor-link   = Evgeni Babsky
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| others        = Translated by Ludmila Aksenova; translation edited by H. C. Creighton (M.A., [[University of Oxford|Oxon]])
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| title         = Human Physiology, in 2 vols.
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| year      = 1989
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| publisher = [[Mir Publishers]]
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| location  = [[Moscow]]
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| language  =
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| isbn      = 5-03-000776-8
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| chapter   = Conditioned-Reflex Activity of the Cerebral Cortex
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| postscript    =  &nbsp;&nbsp;First published in Russian as «Физиология человека»
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}}</ref>{{rp|vol. II, p. 330|}} Conditioned reflexes, in contrast, are a function of the [[cerebral cortex]] and can involve the most varied stimuli applied to different [[Reflexogenous zone|receptive fields]].<ref>For more details, see: Физиология человека (Human Physiology, in Russian) // Под ред. [[:ru:Агаджанян, Николай Александрович|Н.А.Агаджаняна]] и В.И.Циркина. — СПб., 1998. ISBN 5-85503-084-9</ref>{{rp|see a table at page 105|}}
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===Behavioral therapies===
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{{main|Behavior therapy}}
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Some therapies associated with classical conditioning are [[aversion therapy]], [[systematic desensitization]] and [[flooding (psychology)|flooding]]. 
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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.<ref>Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp.336</ref> 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).<ref>Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp136</ref> 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.<ref>Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp133</ref> It is usually with actual exposure to the stimuli, with implosion used for imagined exposure, but the two terms are sometimes used synonymously. [[operant conditioning]].
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Conditioning therapies usually take less time than [[humanistic psychology|humanistic]] therapies.<ref>McGee, Donald Loring. ''Behavior Modification.'' Wellness.com, Inc. 2006. Retrieved on 2012-2-14. http://www.wellness.com/reference/health-and-wellness/behavior-modification</ref>
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===Conditioned drug response===
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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 the case with caffeine; 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 [[drug tolerance]]. 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 compensatory effect; then an overdose reaction may happen if the drug is administered in a different location where the conditioned stimuli are absent.<ref>{{cite book|last=Carlson|first=Neil R.|title=Psychology: The Science of Behaviour|year=2010|publisher=Pearson Education Inc.|location=New Jersey, United States|isbn=978-0-205-64524-4|pages=599–604}}</ref>
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===Conditioned hunger{{anchor|Conditioned hunger}}===
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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.
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===Conditioned emotional response{{anchor|Conditioned emotional response}}===
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{{further|conditioned emotional response|fear conditioning}}
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The influence of classical conditioning can be seen in emotional responses such as [[phobia]], 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.
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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.<ref>{{cite book|last=Carlson|first=Neil R.|title=Psychology: The Science of Behaviour|year=2010|publisher=Pearson Education Inc.|location=New Jersey, United States|isbn=978-0-205-64524-4|pages=198–203}}</ref>
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==In popular culture==
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One of the earliest literary references to classical conditioning can be found in the comic novel ''[[The Life and Opinions of Tristram Shandy, Gentleman]]'' (1759) by [[Laurence Sterne]]. The narrator Tristram Shandy explains<ref>Laurence Sterne: ''The Life and Opinions of Tristram Shandy, Gentleman''; Vol. 1, Chapter 1. IV</ref> how his mother was conditioned by his father's habit of winding up a clock before having sex with her:
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{{quote|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. [...]
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[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.}}
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In the 1932 novel ''[[Brave New World]]'', written by [[Aldous Huxley]], conditioning plays a key role in the maintenance of social peace, especially in maintaining the caste system 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", etc., 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.
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Another example is in the dystopian novel, ''[[A Clockwork Orange]]'' in which the novel's [[anti-hero]] and [[protagonist]], Alex, undergoes a procedure called the [[Ludovico technique]], 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.
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In the science-fiction book ''[[Ender's Shadow]]'', "Pavlovian mental bans" are also  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 [[panic attack]]. 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 received such a ban; he proceeds to become very nice for a time, before eventually committing suicide.
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The [[Metal music|metal]] band [[Rorschach (band)|Rorschach]] have a song titled "Pavlov's dogs"<ref>http://www.discogs.com/Rorschach-Remain-Sedate/master/119334</ref> (the title being an obvious reference to Ivan Pavlov's experiment) whose lyrics also reference classical conditioning.<ref>http://loudsongs.com/r/rorschach/remain-sedate/pavlovs-dogs</ref>
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One of the most popular singles by American [[singer-songwriter]], [[Academy Award]]s and [[Grammy Award]] nominee, [[Aimee Mann|Aimee Mann's]] is the song "Pavlov's Bell," the lyrics of which explicitly compare Mann's own actions to those of the dogs in Pavlov's experiments.  [[Mann|Aimee Mann]] performed the song on the television show ''[[Buffy the Vampire Slayer (TV series)|Buffy the Vampire Slayer]],'' during a 2002 episode<ref>{{cite web|title=Full cast and crew for "Buffy the Vampire Slayer" Sleeper (2002)|url=http://www.imdb.com/title/tt0533485/fullcredits?ref_=tt_cl_sm#cast|publisher=The Internet Movie Database (IMDB)|accessdate=11 March 2013}}</ref>  in which a main cast member is being controlled by a form of classically conditioned trigger.<ref>http://en.wikipedia.org/w/index.php?title=Sleeper_(Buffy_the_Vampire_Slayer)&section=5#Quotes_and_trivia</ref>
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The [[Rolling Stones]] reference Pavlov's early experiments in their song "[[Bitch (The Rolling Stones song)|Bitch]]" with the line "''Yeah when you call my name, I salivate like a Pavlov dog.''"<ref>{{cite web |url=http://www.keno.org/stones_lyrics/bitch.html |title=ROLLING STONES LYRICS: BITCH |publisher=keno.org/ |accessdate=27 January 2012}}</ref>
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In the "[[Phyllis's Wedding]]" episode of [[NBC]]'s TV series ''[[The Office (U.S. TV series)|The Office]]'', Jim conditions Dwight to want a breath mint whenever he hears a computer chime.{{citation needed|date=January 2013}}
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==See also==
 
==See also==
* [[Backward conditioning]]
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{{col-begin}}{{col-break}}
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* [[Behaviorism]]
 
* [[Behaviorism]]
* [[Blocking effect]]
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* [[Conditioned emotional resoponses]]
 
* [[Conditioned responses]]
 
* [[Conditioned taste aversion]]
 
 
* [[Eyeblink conditioning]]
 
* [[Eyeblink conditioning]]
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* [[Fear conditioning]]
 
* [[Fear conditioning]]
* [[Higher order conditioning]]
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* [[Latent inhibition]]
 
* [[Latent inhibition]]
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* [[Learned helplessness]]
 
* [[Learned helplessness]]
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* [[Little Albert experiment]]
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* [[Nocebo]]
 
* [[Nocebo]]
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* [[Measures of conditioned emotional response]] {{nb10}}
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* [[Operant conditioning]]
 
* [[Operant conditioning]]
* [[Orientating responses]]
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* [[Placebo (origins of technical term)]]
 
* [[Placebo (origins of technical term)]]
* [[Quantitative Analysis of Behavior]]
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* [[Rescorla-Wagner model|Rescorla-Wagner model of conditioning]]
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{{col-break}}
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* [[Proboscis extension reflex]]
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* [[Quantitative analysis of behavior]]
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* [[Rescorla–Wagner model|Rescorla–Wagner model of conditioning]]
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* [[Reward system]]
 
* [[Reward system]]
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* [[Preparedness (learning)]]
 
* [[Preparedness (learning)]]
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* [[Second-order conditioning]]
 
* [[Second-order conditioning]]
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* [[Stimulus control]]
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* [[Taste aversion]]
 
* [[Taste aversion]]
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* [[Edwin B. Twitmyer]]
 
* [[Edwin B. Twitmyer]]
* [[Unconditioned responses]]
 
==References & Bibliography==
 
   
==Key texts==
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* [[Poison shyness]]
===Books===
 
* Pavlov, I. P. (1927). ''Conditioned reflexes.'' (G. V. Anrep, Trans.). London: Oxford University Press.
 
   
===Papers===
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{{col-end}}
   
==Additional material==
 
===Books===
 
===Papers===
 
   
* Aguado, L. (2003). Neuroscience of Pavlovian conditioning: A brief overview. ''[[The Spanish Journal of Psychology]], 6,'' 155-167. [http://www.ucm.es/info/Psi/docs/journal/v6_n2_2003/art155.pdf Full text]
 
   
* Antonov, I., Antonova, I., Kandel, E.R., & Hawkins, R.D. (2001). The Contribution of Activity-Dependent Synaptic Plasticity to Classical Conditioning in Aplysia. ''[[Journal of Neuroscience]], 21,'' 6413-6422. [http://www.columbia.edu/~ina4/Publications/J_Neurosci2001.pdf#search='ActivityDependent%20Enhancementclassical%20conditioning' Full text]
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==References==
   
* Dayan, P., Kakade, S., & Montague, P.R. (2000). Learning and selective attention. ''Nature Neuroscience 3,'' 1218 - 1223. [http://www.nature.com/neuro/journal/v3/n11s/pdf/nn1100_1218.pdf Full text]
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; Notes
   
* Kirsch, I., Lynn, S.J., Vigorito, M. & Miller, R.R. (2004). The role of cognition in classical and operant conditioning. ''[[Journal of Clinical Psychology]], 60,'' 369 - 392. [http://artsci.shu.edu/psychology/Bios/Kirsch_et_al_2004.pdf Full text]
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{{Reflist|30em}}
   
* Pavlov, I. P. (1927). ''[http://psychclassics.yorku.ca/Pavlov/ Conditioned Reflexes]: An Investigation of the Physiological Activity of the Cerebral Cortex'' (translated by [[Gleb Vassilievitch von Anrep|G. V. Anrep]]). 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.
 
   
* Weiss, E. & Wilson, S. (2003). The Use of Classical and Operant Conditioning in Training Aldabra Tortoises (''Geochelone gigantea'') for Venipuncture and Other Husbandry Issues. ''Journal of Applied Animal Welfare Science'', 6(1), 33-38.[http://www.psyeta.org/jaaws/full_articles/6.1/weiss.pdf#search='operant%20conditioningreptiles' Full text]
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; Further reading
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*{{cite book
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| last       = Babsky
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| first      = Evgeni
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| authorlink = Evgeni Babsky
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| coauthors  = [[Boris Khodorov]], [[Grigory Kositsky]], [[Anatoly Zubkov]]
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| editor        = 
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| editor-last  = Babsky
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| editor-first = Evgeni
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| editor-link   = Evgeni Babsky
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| others        = Translated by Ludmila Aksenova; translation edited by H. C. Creighton (M.A., [[University of Oxford|Oxon]])
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| title         = Human Physiology, in 2 vols.
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| volume    = 2
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| year      = 1989
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| publisher = [[Mir Publishers]]
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| location  = [[Moscow]]
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| isbn      = 5-03-000776-8
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| pages     = 330–357
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| chapter   = Chapter 17, the section “Conditioned-Reflex Activity of the Cerebral Cortex”
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| postscript    =  &nbsp;&nbsp;First published in Russian as «Физиология человека»
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}}
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* Dayan, P.; Kakade, S. & Montague, P.R. (2000). Learning and selective attention. ''Nature Neuroscience'', 3, 1218–23. [http://www.gatsby.ucl.ac.uk/~beierh/neuro_jc/Dayan_etal00_LearningAttention.pdf Full text]
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* Jami, S.A.; Wright, W.G. & Glanzman, D.L. (2007). [http://www.jneurosci.org/cgi/reprint/27/12/3064 Differential Classical Conditioning of the Gill-Withdrawal Reflex in Aplysia Recruits Both NMDA Receptor-Dependent Enhancement and NMDA Receptor-Dependent Depression of the Reflex]. ''The Journal of Neuroscience'', 27, 3064–8.
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* Kirsch, I.; Lynn, S.J.; Vigorito, M. & Miller, R.R. (2004). The role of cognition in classical and operant conditioning. ''[[Journal of Clinical Psychology]]'', 60, 369–92.
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* Pavlov, I.P. (1927). ''[http://psychclassics.yorku.ca/Pavlov/ Conditioned Reflexes]: An Investigation of the Physiological Activity of the Cerebral Cortex'' (translated by [[Gleb Vassilievitch von Anrep|G.V. Anrep]]). London: Oxford University Press. [http://books.google.com/books?id=cknrYDqAClkC&printsec=frontcover&dq=%22conditioned+reflexes%22&hl=en&ei=SsMCTfCwF4GUvAOwyLXNBg&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCcQ6AEwAA#v=onepage&q&f=false Google preview of Dover 2003 reprint]
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* 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.
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*{{cite book
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| last       = Schmidt
  +
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| first      = R. F.
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| authorlink = 
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| editor        = 
  +
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| editor1-last  = Schmidt
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| editor1-first = Robert F.
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| editor1-link  = Robert F. Schmidt
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| editor2-last  = Thews
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| editor2-first = Gerhard
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| editor2-link  = Gerhard Thews
  +
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| others        = Translated by Marguerite A. Biederman-Thorson
  +
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| title         = Human Physiology
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| url           = 
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| edition   = Second, completely revised
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| year      = 1989
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| publisher = [[Springer-Verlag]]
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| location  = Berlin etc.
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| isbn      = 3-540-19432-0
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| pages     = 155–156
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| chapter   = Behavior Memory (Learning by Conditioning)
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}}
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* [http://en.wikibooks.org/wiki/Animal_Behavior/Learning#Associative_Learning wiki book on Animal behavior]
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*Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print.
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*Douglas L. Medin, Brian H. Ross, and Arthur B. Markman. Cognitive Psychology. N.p.:n.p,2009. Print
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*Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print.
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==External links==
 
==External links==
   
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* [http://www.scholarpedia.org/article/Classical_Conditioning Scholarpedia Classical conditioning]
   
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* [http://www.scholarpedia.org/article/Computational_Models_of_Classical_Conditioning Scholarpedia Computational models of classical conditioning]
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* [http://www.scholarpedia.org/article/Hermissenda Scholarpedia Hermissenda]
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{{Memory}}
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{{Learning}}
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{{Template:Learningtheory}}
 
{{Template:Learningtheory}}
 
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{{enWP| Classical_conditioning}}
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[[Category:Experimental psychology]]
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[[Category:Behavioral concepts]]
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[[Category:History of psychology]]
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[[Category:Russian inventions]]
 
[[Category:Behaviorism]]
 
[[Category:Behaviorism]]
[[Category:Conditioning]]
 
 
[[Category:Learning]]
 
[[Category:Learning]]
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[[Category:Conditioning]]
 
[[Category:Learning theory]]
 
[[Category:Learning theory]]
 
[[Category:Classical conditioning]]
 
[[Category:Classical conditioning]]

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Classical conditioning (also Pavlovian conditioning or respondent conditioning) is a kind of learning that occurs when a conditioned stimulus (CS) is paired with an unconditioned stimulus (US). Usually, the CS is a neutral stimulus (e.g., the sound of a tuning fork), the US is biologically potent (e.g., the taste of food) and the unconditioned response (UR) to the US 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 CS when the CS is presented alone.  The CR is usually similar to the UR (see below), but unlike the UR, it must be acquired through experience and is relatively impermanent.[1]


Classical conditioning differs from operant or instrumental conditioning, in which a behavior is strengthened or weakened, depending on its consequences (i.e., reward or punishment).[2]


A classic experiment by Pavlov exemplifies the standard procedure used in classical conditioning.[3] First Pavlov observed the UR (salivation) produced when meat powder (US) was placed in the dog's mouth. He then rang a bell (CS) before giving the meat powder. After some repetitions of this pairing of bell and meat the dog salivated to the bell alone, demonstrating what Pavlov called a "conditional" response, now commonly termed "conditioned response" or CR. 


In conditioning the CS is not simply connected to UR. For example, the CR usually differs in some way from the UR; sometimes it is a lot different. For this and other reasons, learning theorists commonly suggest that the CS comes to signal or predict the US, and go on to analyze the consequences of this signal.[4] Robert A. Rescorla 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."[5]


Procedures

Ivan Pavlov provided the most famous example of classical conditioning, although Edwin Twitmyer published his findings a year earlier (a case of simultaneous discovery).[3]   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 then gave the dog food; 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.[6] 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.[7]


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.[2][5] 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. 

File:Delay,trace conditioning.svg


Forward conditioning

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.[8][9] 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.


File:Forward Conditioning.svg


Simultaneous conditioning

File:Classical Conditioning.svg


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.


File:Simultaneous Conditioning.svg


Second-order and higher-order conditioning

Main article: Second-order conditioning

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.[10] 

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


File:Second Order Conditioning.svg


Backward conditioning

Backward conditioning occurs when a CS immediately follows a US.[8] 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.[11] For example, a puff of air directed at a person's eye could be followed by the sound of a buzzer.


Temporal conditioning

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 Animal cognition).


File:Temporal Conditioning.svg


Zero contingency procedure

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.[12] This finding -  that prediction rather than CS-US pairing is the key to conditioning - greatly influenced subsequent conditioning research and theory.


Extinction

Main article: Extinction (psychology)    

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.


Phenomena observed

Acquisition

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[2][4] 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.[13]


Extinction

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".[4]


File:Classical conditioning - extinction.svg


External inhibition

External inhibition 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.


Recovery from extinction

Several procedures lead to the recovery of an extinguished CR. The following examples assume that the CS has been 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 [2]

  • 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 (psychology)

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:

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

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.[4] The more the test stimulus differs from the CS the more the conditioned response will differ from that previously observed. Appercepting more stimuli from  the environment will cause the more widely spreadout CR in the brain cellular network, that is called  GENERALIZED. WIth more in-phased braincells in chain the complete brain will show a significant reaction with the generalization on almost any CS stimulus in apperception.[14]


Stimulus discrimination

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.[4]


Latent inhibition

Main article: Latent inhibition

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.[4]


Conditioned suppression

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 operant conditioning.  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 classical conditioning; 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.)


Conditioned inhibition

Three phases of conditioning are typically used:

Phase 1
A CS (CS+) is paired with a US until asymptotic CR levels are reached.


Phase 2
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.


Phase 3
  • 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.


Blocking

Main article: Blocking effect

This form of classical conditioning involves two phases.

Phase 1
A CS (CS1) is paired with a US.


Phase 2
A compound CS (CS1+CS2) is paired with a US.


Test
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.


File:Classical conditioning - blocking.svg


Theories

Data sources

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.[15]  Most relevant experiments have used the classical conditioning procedure, although instrumental (operant) conditioning 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  autoshaping .


Stimulus-substitution theory

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.[16] 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.


The Rescorla–Wagner model

Main article: Rescorla–Wagner model


The Rescorla–Wagner (R–W) model[2][17]  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.[18][19]


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.


The equation

 ∆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.[20] 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 changes during learning; 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.


R–W model:  acquisition

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).[21] 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.


R–W model: extinction

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 reaches zero; 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).


R–W model: blocking

Main article: Blocking effect

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.[21]


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.


Theoretical issues and alternatives to the Rescorla–Wagner model

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.[2][22]   Following are brief summaries of some related theoretical issues.[18]


The content of learning

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.[2]


The role of attention in learning

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 Nicholas Mackintosh,[23] 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[24]  Although neither model explains all conditioning phenomena, the attention idea still has an important place in conditioning theory.[2]


Context

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.[13] Such so-called “context” stimuli are always present;  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.[2]


Comparator theory

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 “performance based;”, 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.[25][26]  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.[2][18]


Computational theory

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 (2000, 2002).[27][28] 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 Animal cognition), and the Gallistel & Gibbon model yields very good quantitative fits to a variety of experimental data.[4][18] However, recent studies have suggested that duration-based models cannot account for some empirical findings as well as associative models.[29]


Applications

Neural basis of learning and memory

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, fear conditioning, eyeblink conditioning, and the foot contraction conditioning of Hermissenda crassicornis, a sea-slug.


In their textbook on human physiology, Nikolai Agajanyan 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 the neural processes;  A leading role in the performance of unconditioned reflexes is played by the lower divisions of the higher nervous system, the subcortical nuclei, brain stem and spinal cord.[30]:vol. II, p. 330 Conditioned reflexes, in contrast, are a function of the cerebral cortex and can involve the most varied stimuli applied to different receptive fields.[31]:see a table at page 105


Behavioral therapies

Main article: Behavior therapy

Some therapies associated with classical conditioning are aversion therapy, systematic desensitization and flooding

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.[32] 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).[33] 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.[34] It is usually with actual exposure to the stimuli, with implosion used for imagined exposure, but the two terms are sometimes used synonymously. operant conditioning.


Conditioning therapies usually take less time than humanistic therapies.[35]


Conditioned drug response

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 the case with caffeine; 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 drug tolerance. 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 compensatory effect; then an overdose reaction may happen if the drug is administered in a different location where the conditioned stimuli are absent.[36]


Conditioned hunger

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.


Conditioned emotional response

Further information: conditioned emotional response

The influence of classical conditioning can be seen in emotional responses such as phobia, 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.[37]


In popular culture

One of the earliest literary references to classical conditioning can be found in the comic novel The Life and Opinions of Tristram Shandy, Gentleman (1759) by Laurence Sterne. The narrator Tristram Shandy explains[38] 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 Brave New World, written by Aldous Huxley, conditioning plays a key role in the maintenance of social peace, especially in maintaining the caste system 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", etc., 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 dystopian novel, A Clockwork Orange in which the novel's anti-hero and protagonist, Alex, undergoes a procedure called the Ludovico technique, 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 science-fiction book Ender's Shadow, "Pavlovian mental bans" are also  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 panic attack. 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 received such a ban; he proceeds to become very nice for a time, before eventually committing suicide.


The metal band Rorschach have a song titled "Pavlov's dogs"[39] (the title being an obvious reference to Ivan Pavlov's experiment) whose lyrics also reference classical conditioning.[40]


One of the most popular singles by American singer-songwriter, Academy Awards and Grammy Award nominee, Aimee Mann's is the song "Pavlov's Bell," the lyrics of which explicitly compare Mann's own actions to those of the dogs in Pavlov's experiments.  Aimee Mann performed the song on the television show Buffy the Vampire Slayer, during a 2002 episode[41]  in which a main cast member is being controlled by a form of classically conditioned trigger.[42]


The Rolling Stones reference Pavlov's early experiments in their song "Bitch" with the line "Yeah when you call my name, I salivate like a Pavlov dog."[43]


In the "Phyllis's Wedding" episode of NBC's TV series The Office, Jim conditions Dwight to want a breath mint whenever he hears a computer chime.[citation needed]


See also


References

Notes
  1. Cherry, Kendra What Is a Conditioned Response?. About.com Guide. About.com. URL accessed on 2013-02-10.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Bouton, M. E. (2007) Learning and Behavior: A Contemporary Synthesis, Sunderland, MA: Sinauer
  3. 3.0 3.1 Pavlov, I. P. (1927/1960). Conditional Reflexes. New York: Dover Publications (the 1960 edition is not an unaltered republication of the 1927 translation by Oxford University Press http://psychclassics.yorku.ca/Pavlov/).
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Shettleworth, Sara J.(2010) Cognition, Evolution, and Behavior (2nd edn) Oxford Univ. Press
  5. 5.0 5.1 Rescorla, Robert A. Pavlovian Conditioning — It's Not What You Think It Is. (1988) American Psychologist, 43, 151-160.
  6. Douglas L. Medin, Brian H. Ross, and Arthur B. Markman. Cognitive Psychology. N.p.:n.p,2009. Print 50-53
  7. T.L. Brink (2008) Psychology: A Student Friendly Approach. "Unit 6: Learning." pp. 97–98
  8. 8.0 8.1 Chang, Raymond C.; Stout,Steven; 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.
  9. Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. 69
  10. Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp.66
  11. Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp.71
  12. Rescorla, R. A. (1967). Pavlovian conditioning and its proper control procedures.  Psychological Review, 74, 71-80
  13. 13.0 13.1 Schacter, Daniel L (2009). PSYCHOLOGY, 267, Catherine Woods.
  14. Schacter, Daniel L (2009). PSYCHOLOGY, 269, Catherine Woods.
  15. Shettleworth, S. J. (2010) Cognition, Evolution and Behavior (2nd Ed), New York: Oxford.
  16. Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp. 84
  17. 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.
  18. 18.0 18.1 18.2 18.3 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
  19. Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp. 85
  20. Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print pp 85-89
  21. 21.0 21.1 Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 2008. Print. pp. 85-89
  22. Miller, R. R., Barnet, R. C. & Grahame, N. J. (1995) Assessment of the Rescorla–Wagner model.  Psychological Bulletin, 117, 363-386
  23. Mackintosh, N. J. (1975) A theory of attention: Variations in the associability of stimuli with reinforcement  Psychological Review, 82, 276-298
  24. Pearce, J. M. & Hall, G. (1980) A model for Pavlovian learning: Variations in the effectiveness of conditioned but not of unconditioned stimuli. Psychological Review, 87, 532-552.
  25. 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
  26. Miller, R. R. & Escobar, M. (2001) Contrasting acquisition-focused and performance-focused models of acquired behavior. Current Directions in Psychological Science 10, 141-145.
  27. Gallistel, R. & Gibbon, J. (2000). Time, rate and conditioning. Psychological Review, 107, 289-304.
  28. Gallistel, R. & Gibbon, J. (2002) The Symbolic Foundations of Conditioned Behavior. Mahwah, NJ: Erlbaum
  29. Golkar, A., Bellander, M., & Öhman, A. (2013). Temporal properties of fear extinction--does time matter? "Behavioral neuroscience", 127(1), 59–69.
  30. {{{title}}}, Mir Publishers.
  31. For more details, see: Физиология человека (Human Physiology, in Russian) // Под ред. Н.А.Агаджаняна и В.И.Циркина. — СПб., 1998. ISBN 5-85503-084-9
  32. Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp.336
  33. Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp136
  34. Kearney, Christopher A. Abnormal Psychology and Life: A Dimensional Approach.N.p.: n.p., January 1, 2011. Print. pp133
  35. McGee, Donald Loring. Behavior Modification. Wellness.com, Inc. 2006. Retrieved on 2012-2-14. http://www.wellness.com/reference/health-and-wellness/behavior-modification
  36. Carlson, Neil R. (2010). Psychology: The Science of Behaviour, 599–604, New Jersey, United States: Pearson Education Inc..
  37. Carlson, Neil R. (2010). Psychology: The Science of Behaviour, 198–203, New Jersey, United States: Pearson Education Inc..
  38. Laurence Sterne: The Life and Opinions of Tristram Shandy, Gentleman; Vol. 1, Chapter 1. IV
  39. http://www.discogs.com/Rorschach-Remain-Sedate/master/119334
  40. http://loudsongs.com/r/rorschach/remain-sedate/pavlovs-dogs
  41. Full cast and crew for "Buffy the Vampire Slayer" Sleeper (2002). The Internet Movie Database (IMDB). URL accessed on 11 March 2013.
  42. http://en.wikipedia.org/w/index.php?title=Sleeper_(Buffy_the_Vampire_Slayer)&section=5#Quotes_and_trivia
  43. ROLLING STONES LYRICS: BITCH. keno.org/. URL accessed on 27 January 2012.


Further reading
  • Dayan, P.; Kakade, S. & Montague, P.R. (2000). Learning and selective attention. Nature Neuroscience, 3, 1218–23. Full text
  • Kirsch, I.; Lynn, S.J.; Vigorito, M. & Miller, R.R. (2004). The role of cognition in classical and operant conditioning. Journal of Clinical Psychology, 60, 369–92.
  • 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.


  • Chance, Paul. Learning and Behavior. Belmont/CA: Wadsworth, ISBN 0-495-09564-8, 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.


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Baddeley | Broadbent |Ebbinghaus  | Kandel |McGaugh | Schacter  | Treisman | Tulving  |
Philosophy and historical views of memory
Aristotle | [[]] |[[]] |[[]] |[[]] | [[]] | [[]] | [[]] |
Miscellaneous
Journals | Learning, Memory, and Cognition |Journal of Memory and Language |Memory |Memory and Cognition | [[]] | [[]] | [[]] |



Template:Learning





 

Learning
Types of learning
Avoidance conditioning | Classical conditioning | Confidence-based learning | Discrimination learning | Emulation | Experiential learning | Escape conditioning | Incidental learning |Intentional learning | Latent learning | Maze learning | Mastery learning | Mnemonic learning | Nonassociative learning | Nonreversal shift learning | Nonsense syllable learning | Nonverbal learning | Observational learning | Omission training | Operant conditioning | Paired associate learning | Perceptual motor learning | Place conditioning | Probability learning | Rote learning | Reversal shift learning | Second-order conditioning | Sequential learning | Serial anticipation learning | Serial learning | Skill learning | Sidman avoidance conditioning | Social learning | Spatial learning | State dependent learning | Social learning theory | State-dependent learning | Trial and error learning | Verbal learning 
Concepts in learning theory
Chaining | Cognitive hypothesis testing | Conditioning | Conditioned responses | Conditioned stimulus | Conditioned suppression | Constant time delay | Counterconditioning | Covert conditioning | Counterconditioning | Delayed alternation | Delay reduction hypothesis | Discriminative response | Distributed practice |Extinction | Fast mapping | Gagné's hierarchy | Generalization (learning) | Generation effect (learning) | Habits | Habituation | Imitation (learning) | Implicit repetition | Interference (learning) | Interstimulus interval | Intermittent reinforcement | Latent inhibition | Learning schedules | Learning rate | Learning strategies | Massed practice | Modelling | Negative transfer | Overlearning | Practice | Premack principle | Preconditioning | Primacy effect | Primary reinforcement | Principles of learning | Prompting | Punishment | Recall (learning) | Recency effect | Recognition (learning) | Reconstruction (learning) | Reinforcement | Relearning | Rescorla-Wagner model | Response | Reinforcement | Secondary reinforcement | Sensitization | Serial position effect | Serial recall | Shaping | Stimulus | Reinforcement schedule | Spontaneous recovery | State dependent learning | Stimulus control | Stimulus generalization | Transfer of learning | Unconditioned responses | Unconditioned stimulus 
Animal learning
Cat learning | Dog learning  Rat learning 
Neuroanatomy of learning
Neurochemistry of learning
Adenylyl cyclase  
Learning in clinical settings
Applied Behavior Analysis | Behaviour therapy | Behaviour modification | Delay of gratification | CBT | Desensitization | Exposure Therapy | Exposure and response prevention | Flooding | Graded practice | Habituation | Learning disabilities | Reciprocal inhibition therapy | Systematic desensitization | Task analysis | Time out 
Learning in education
Adult learning | Cooperative learning | Constructionist learning | Experiential learning | Foreign language learning | Individualised instruction | Learning ability | Learning disabilities | Learning disorders | Learning Management | Learning styles | Learning theory (education) | Learning through play | School learning | Study habits 
Machine learning
Temporal difference learning | Q-learning 
Philosophical context of learning theory
Behaviourism | Connectionism | Constructivism | Functionalism | Logical positivism | Radical behaviourism 
Prominant workers in Learning Theory|-
Pavlov | Hull | Tolman | Skinner | Bandura | Thorndike | Skinner | Watson 
Miscellaneous|-
Category:Learning journals | Melioration theory 
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