Classic conditioning

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One of Pavlov's dogs

Classical conditioning is a behavioristic learning theory founded by the Russian physiologist Ivan Petrovich Pavlov , which states that a new, conditioned reaction can be added to a natural, mostly innate, so-called unconditional reaction through learning . A well-known example is the Pavlovian dog : when it was given food, a bell always sounded at the same time. After a few such feedings, the dog's saliva began to flow just after the well-known sound of the bell.

The assumptions and techniques of classical conditioning can also be used to treat anxiety, compulsions, or anxiety-like symptoms. Such techniques are known as counter conditioning , aversion therapy , systematic desensitization , extinction and “flooding” .

Instrumental and operant conditioning , which affect spontaneous behavior, must be distinguished from classical conditioning, which affects triggered behavior .


There is an unconditional (also: “unconditional”) stimulus (in the dog example: the food in the dog's mouth), which is followed as a reflex by an unconditional (also: “unconditional”) reaction (in the dog example: stronger salivation). If one presents a previously neutral stimulus several times in connection with the unconditional stimulus ("coupling", in the dog example: bell tone), then this previously neutral stimulus becomes a conditioned stimulus. This conditioned stimulus now also triggers a reflex reaction (the conditioned reaction), which is usually very similar to the unconditional reaction (in the dog example: after successful learning, the bell tone triggers more salivation).

The neutral (later: conditional) stimulus must not initially cause a specific reaction, but it must be perceived as a discrete stimulus, e.g. B. trigger an orientation reaction.

German English Abbreviation Explanation
Unconditional attraction unconditioned stimulus US (UCS) Stimulus that triggers a reaction without prior learning
Absolute response unconditioned response UR (UCR) innate response that is triggered by the US
Neutral stimulus neutral stimulus NS Stimulus that does not trigger a specific response
Conditional stimulus conditioned stimulus CS originally neutral stimulus due to repeated

Coupling with a US causes a learned or conditioned response

Conditional response conditioned response CR learned reaction that is triggered by the CS
Classical conditioning in a nutshell
Control phase before training neutral stimulus → no specific reaction
absolute charm → unconditional reaction
Learning phase training neutral stimulus + unconditional stimulus → unconditional reaction
Learning outcome Result conditioned stimulus → conditional reaction

Pavlov was inspired by the reflex theory of Ivan Mikhailovich Setschenow . In addition to the reflex-theoretical assumption of an SR association, empirical data also support the assumption of an SS association. Pavlov himself was often erroneously referred to as an SR theorist, but assumed an association between CS and US in his stimulus substitution theory.


The Pavlovian Dog

The best-known example is the Pavlovian dog, in which the giving of food was always associated with a bell sound. After several repetitions, the dog was salivating just at the sound of the bell.

Control phase (before training):

  • Bell tone (neutral stimulus) leads to ear tips (no specific reaction)
  • Food (unconditional stimulus) leads to salivation (unconditional reaction)

Learning phase:

  • repeated pairing of bell tone (neutral stimulus / stimulus) + food (unconditional stimulus / stimulus) + salivation (unconditional reaction)

Learning outcome

  • Bell tone (now conditional stimulus / stimulus) leads to salivation (conditional reaction)

Air raid

Another example is intended to illustrate the process of classic conditioning in human behavior:

The falling of the bombs in World War II created fear among people. Usually, however, before the first bombs fell, sirens (“ air raid alarms ”) sounded with a specific increasing and decreasing howling sound. For many people, the howling sound caused fear after the second repetition of the air raid alarm. “Even in peacetime, the siren triggers fear in numerous people, even if it is just a test alarm.” (Edelmann, 1996, p. 63) In unconditioned people, the howling sound alone could not trigger a significant reaction. The reaction (fear) was only conditioned by the combination of the howling sound and the falling of bombs: Because the two stimuli were in a direct chronological sequence, the howling sound was associated with the falling of the bombs and the unconditional reaction (fear of falling Feeling bombs) became a conditional reaction (feeling afraid at the sound of the howling). The classical conditioning model was expanded after it was found that the very idea of ​​sounding an air-raid alarm led to anxiety.

Excitatory and inhibitory conditioning

Excitatory classic conditioning is the coupling of a previously neutral stimulus to a stimulus that triggers innate behavior, so to speak, the "classic" classic conditioning.

Example: child is afraid when thunder rolls; the (silent) lightning announces the thunder, so it already triggers fear. Thunder = UCS (unconditioned stimulus); Lightning = CS (conditioned stimulus); Anxiety = UCR (unconditioned response), becomes CR (conditioned response).

However, an organism can also learn that the conditioned stimulus is linked to the absence of an (excitatory) unconditional stimulus. Then one speaks of inhibitory classical conditioning. Example: The child is afraid of thunder (UCS), but not when the mother (CS) is there.

Effective designs

Depending on how the temporal relationship between the conditioned stimulus and the unconditional stimulus is chosen in the learning phase (also: “acquisition”), the conditioning is effective in different ways. In the extensive research, the following interstimulus intervals have mainly been used:

short delayed conditioning
The conditioned stimulus is presented, and shortly afterwards, but while the conditioned stimulus is still on, the unconditional stimulus;
long delayed conditioning
The conditioned stimulus is presented and some time later, but while the conditioned stimulus is still on, the unconditional stimulus. There is no clear limit to the short delay, but: the shorter the delay, the more effective the learning;
simultaneous conditioning
Conditioned stimulus and unconditional stimulus are presented simultaneously, ineffective;
trace conditioning
First the conditioned stimulus is presented, then the unconditional stimulus; requires stimulus coupling on the memory trail;
backward conditioning
The conditioned stimulus is presented after the unconditional stimulus; only works with inhibitory conditioning.

The conditioning usually works best when the neutral and the unconditional stimulus follow one another shortly ( contiguity ). In some cases, however, the conditioning also works if there are hours between the two stimuli (e.g. association of a nausea reaction with the taste of blueberries because you happened to eat blueberries the night before, see taste aversion ). The decisive factor for conditioning, however, is the contiguity between the conditioned stimulus and the unconditional stimulus: The conditioned reaction is only developed when the conditioned stimulus takes on a signal character, i.e. predicts the unconditional stimulus with a certain probability.

The number of repetitions of the coupling of the conditioned and unconditional stimulus also has an impact on the learning process. “As a rule, the acquisition of a conditioned response (CR) is linked to the repeated occurrence of these two stimuli. We want to call this principle reinforcement. "(Edelmann, 2000, p. 37f.)

The novelty and salience of stimuli are also important for the effectiveness of stimuli .

The unconditional and the conditional reaction need not have the same phenomenology (as in Pavlov's experiment). An example of this is shock conditioning in humans: the unconditional reaction is a startle reaction, combined with an increase in heart rate and blood pressure. If you test the conditioned reaction after training, however, it consists of a lowering of the heart rate.

Biological strength

If the conditioning is successful, the stimulus of an existing stimulus-reaction pair (e.g. humming sound → turning head towards the sound source) is "bent over" to another reaction (e.g. salivation), as has been said since Pavlov, this new stimulus -Reaction binding has greater biological strength than the old one. Conversely, a stimulus is not suitable as a NS / CS for a new stimulus-reaction bond if it is already too strongly tied to the triggering of another reaction. The counter-conditioning only works if the new US triggers its (new, desired) reaction more strongly than the old US its (now to be deleted) reaction.

Latent inhibition

In the case of latent inhibition (also known as CS pre-exposure), a stimulus that reliably does not produce a triggered reaction is then more difficult to learn than CS than an unknown stimulus. A weakened ability for latent inhibition is suspected in schizophrenics and creative geniuses .

Latent escapement is an example of what the Rescorla-Wagner model cannot explain. Lubow and Moore (1959) carried out an experiment with sheep and geese.

Conditional inhibition

When the conditioned stimulus (CS) elicits the same response as the unconditional stimulus (as in the examples), it is called excitatory conditioning. If there is another stimulus that is reliably not followed by US, this previously neutral stimulus becomes an inhibitory conditioned stimulus (CS-), which ensures that the conditioned reaction to the excitatory related stimulus (CS +) is weaker or even weaker does not occur (so-called conditional inhibition or conditional inhibition ). If the CS + is an aversive stimulus, the CS- can be interpreted as a safety signal. The simplest and most effective procedure to turn a neutral stimulus into an inhibitor is to present it simultaneously with the CS +, but without following the US.


The same conditioned stimulus is not necessarily required to trigger the conditioned response. Pavlov found in his investigations that the secretion of saliva is also triggered by a stimulus that resembled the ringing signal: stimulus generalization had taken place. The dog now reacted with saliva even after the sound of a gong or flute. The generalization or the generalization effect is a process: “[...] in which the organism also reacts to stimuli that are similar to the conditioned stimulus; no additional conditioning is required for each similar stimulus. "


Discrimination refers to the process that counteracts stimulus generalization. The organism learns to react only to specific stimuli and to distinguish them from similar ones. For example, Pavlov's dog was able to learn to react only to specific stimuli, such as the tones of a bell, but not to other acoustic stimuli with salivation. This process, which describes learning to discriminate, enables living beings to react differently to similar stimuli and therefore more appropriately.

Extinction (extinction)

If the conditioned stimulus (CS) is repeatedly presented without a subsequent unconditional stimulus (US), the reaction (CR) becomes weaker and weaker and ultimately does not occur: The CS has lost its signal character for the US, this process is called extinction (extinction ). However, if the process with the conditioned stimulus (CS) is repeated at a later point in time, the conditioned reaction often occurs again (so-called “spontaneous recovery”), albeit with a lower intensity than before the extinction.

Strictly speaking, it follows from Pavlov's theory that once a reflex has been learned, it can never be completely erased. The absence of the US only makes it weaker. This inhibition is initially not permanent, which leads to the phenomenon of spontaneous recovery of the reflex. Pavlov himself never used the term extinction; he always wrote of inhibition and weakening . In the English translation it became extinction . Since Pavlov's works were then translated from English into German (instead of directly from Russian), the translation error also established itself in German as a technical term ( extinction or deletion ).

"Emotional-motivational reactions are often very resistant to deletion". Edelmann addresses this special case in an example: "Children and adults alike are sometimes afraid of relatively small dogs, although unpleasant experiences with such animals can no longer be remembered at all."

Counter conditioning

If a conditioned stimulus (CS) has been learned so that it reliably triggers a conditioned response (CR 1 ), this association should be resolved again in the counter-conditioning. To do this, the CS is now paired with a new unconditional stimulus, which triggers a CR 2 reaction that is opposite to the CR 1 . So if the CR 1 was aversive, the CR 2 is appetizing and vice versa. Has z. For example, if a rat learns a tone (CS) as a predictor for electrical stimuli (US 1 ), so that the tone alone triggers a fear reaction (CR 1 ), the tone is counter-conditioned with an appetizing stimulus (US 2 , e.g. . Feeding) paired until the sound no longer triggers the fear response. For information on the use of counter-conditioning in psychotherapy, see Counter-conditioning .

Second order conditioning

If a neutral stimulus is paired with an unconditional stimulus, one speaks of first-order conditioning . The second-order conditioning is built on a previously learned stimulus-reaction link, which means that a neutral stimulus is now linked to a conditioned stimulus that triggers a conditioned reaction. It only works if the second CS is biologically weaker than the first CS. Pavlov initially conditioned the ticking of a metronome as CS for food (first-order conditioning). Then he paired the metronome with the sight of a black square (second order conditioning). After this learning phase, the black square caused saliva to flow even though it had never been paired with the food.


If the US produces a general, unspecific increase in willingness to react, so that the reaction to the CS is based on this excitation and not on learning, one speaks of "pseudo-conditioning". To ensure that the learning effects observed in the experimental group are not based on pseudo-conditioning, a control group is presented with the same amount and the same distribution of CS and US, but without a temporal connection. Two common control procedures are 1. random and 2. explicitly unpaired presentation of CS and US.

Blocking effect

If stimulus A is conditioned as a conditioned stimulus in a first learning phase and then an attempt is made to condition the combination of stimulus A and a further stimulus B in a second learning phase as a conditioned stimulus, then stimulus B alone cannot trigger the conditioned reaction (chimney, 1968). The association between stimulus A and unconditional response acquired in learning phase 1 "blocks" the formation of an association between stimulus B and the unconditional stimulus in learning phase 2. The fact that after phase 2 the conditioned reaction is triggered by the stimulus combination A + B is apparently due to stimulus A alone. The blocking effect refutes the assumption that contiguity is the decisive criterion for the formation of an association between two stimuli, because the contiguity between stimulus B and the unconditional stimulus was given perfectly in learning phase 2. This discovery led to the development of the Rescorla-Wagner model , which states that the novelty and salience of the conditioned stimulus determine how strongly it influences behavior.


Web links

Individual evidence

  1. Matthias Brand, John Schiebener: General Psychology I . Kohlhammer, 2014, ISBN 978-3-17-025470-1 ( ).
  2. Jochen Müsseler, Martina Rieger: General Psychology . Springer-Verlag, 2016, ISBN 978-3-642-53898-8 ( [accessed on May 16, 2017]).
  3. ^ Lubow, Gewirtz: Latent inhibition in humans: data, theory, and implications for schizophrenia . In: Psychological Bulletin , 1995, pp. 87-103.
  4. Gerd Mietzel: Pedagogical psychology of learning and teaching. 8th, revised and expanded edition. Hogrefe Verlag, 2007, p. 144.
  5. a b Edelmann, 2000, p. 38.
  6. ^ Wickens, Delos D. & Wickens, Carol D. (1942). Some factors related to pseudo-conditioning. Journal of Experimental Psychology, 31 (6), 518-526.