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AP Psych



Unit 4

4.2 Classical Conditioning

6 min readjanuary 22, 2021

John Mohl

Dalia Savy

What is Classical Conditioning?

Classical Conditioning is most closely associated with the work of Ivan Pavlov, which is why it is sometimes referred to as Pavlovian Conditioning. Classical conditioning involves the environment presenting a stimulus that makes the organism respond in a certain way. The graphic below shows how Pavlov paired a neutral stimulus (bell/whistle 🔔) with an unconditioned stimulus (food), to elicit a conditioned response (salivation) from the whistle alone. 🎥 Watch: The OfficeClassical Conditioning


Image Courtesy of Open Source Textbook.

The Stimulus

The stimulus (plural: stimuli) can be anything that is perceivable by the five major senses. It can be a sight, sound, taste, smell, or something that can be felt. The response, in classical conditioning, is any reflexive, non-voluntary behavior, i.e., something that one cannot readily control.

Examples of reflexive, non-voluntary responses: 

  • 💓Heartbeat/ Heart rate

  • 😤Breathing/Respiration 

  • 🤤Salivation (mouth watering)

  • 😲Startle response

  • 🥶Shivering

Some of the stimulus-response pairings (or contingencies) are the result of the experiences to our own environments. We have learned to react to certain stimuli in a certain way. For example, if a one-hundred dollar bill 💵 is placed in our hands, we might feel our bodies react as the result of the excitement we might feel: our heart rate and respiration might go up.

However, we were not born to react that way; giving that same hundred-dollar bill to a baby would not yield the same reaction. When a response to a stimulus is the result of learning, we refer to it as conditioned, or a conditioned response (CR). The stimulus that causes the conditioned response is called the conditioned stimulus (CS).

Some of these stimulus-response pairings (or contingencies) are natural, innate, and unlearned. That is, we are born to react to certain stimuli in a certain way. When a light is shined in one’s eyes ☀️, the pupils constrict; this is a natural process. When a response to a stimulus is natural and unlearned, we refer to it as unconditioned or an unconditioned response (UR). The stimulus that causes the unconditioned response is called the unconditioned stimulus (US).

Conditioning Processes

During the acquisition stage, a neutral stimulus (NS), which does not produce a noticeable response, acquires the ability to affect the same response as the unconditioned response. In AP Psychology, the neutral stimulus is typically presented before the unconditioned stimulus, which naturally produces the unconditioned response. After numerous pairings of the neutral stimulus and unconditioned stimulus, the neutral stimulus creates the response by itself. What was once the neutral stimulus becomes a conditioned stimulus, and the reaction to it, a conditioned response.

If a conditioned stimulus is presented numerous times without being paired with the unconditioned stimulus, there may be less of a conditioned response, and it may even eventually cease. In this instance, the conditioned response has gone into extinction. Extinction🦕 is when a conditioned stimulus no longer produces a conditioned response.

Even when extinction occurs, there are times in which the conditioned stimulus, having been shown to no longer produce the conditioned response, will unexpectedly affect the conditioned response. This is referred to as spontaneous recovery. Spontaneous recovery is a time following extinction when a conditioned stimulus restarts to create the conditioned response.


Image courtesy of Open Source Textbook.

Stimulus generalization, or generalization, refers to when stimuli that are similar to the conditioned stimulus also produce the conditioned response. For example, if a person is conditioned to have an elevated heart rate at the appearance of a blue ball 🔵, and shows that same conditioned response to anything that's blue 🌃, the conditioning is said to be generalized.

Stimulus discrimination is the exact opposite of generalization, in which one fails to produce a conditioned response to stimuli that are similar to the conditioned stimulus, and only produces the conditioned response to the actual conditioned stimulus as it was originally presented. In the previous example, a person has been conditioned to respond to a blue ball. However, the response only occurs in response to that shade of blue only.

Not all conditioning is built on an original unconditioned stimulus-unconditioned response pairing. For example, a worker who becomes excited (e.g., elevated heart rate) at the sight of their paycheck very likely did not have the bodily conditioned response, because the paycheck was originally paired with something that naturally produced that type of bodily response.

Very likely it was paired with money or the reception of money 💰, which in itself is not an unconditioned stimulus (that is, it is not natural). Instead, the money as a conditioned stimulus was established by being paired with some other type of stimulus. Because the paycheck-excitement contingency was initiated on a previously conditioned stimulus, it is referred to as higher order conditioning. Higher order conditioning refers to conditioning that is built on previously established conditioning.

Table Summary

Key TermDefinition Example and Emoji Representation (pretend 💨 represents a whistle)
Neutral Stimulus (NS)Stimulus that elicits no response (before any conditioning happens)In the Pavlov's dog example, the whistle is the NS. If it is blown before conditioning, the dog does nothing. 💨→😑
Unconditioned Stimulus (US)Stimulus that implicitly triggers a response. (before any conditioning happens)The US is the dog's food. When the dog sees food, it already has a reaction and becomes hungry. 🦴→🤤
Unconditioned Response (UR)A natural response to the US. (before any conditioning happens)The UR is salivation. When a dog sees the dog food (US), it automatically salivates because it's hungry. 🦴→🤤
ConditioningThe goal of this experiment is to make the dog salivate when the whistle is blown. This obviously isn't a natural reaction, so you must classical condition the dog to react like that. In order to do this, Pavlov showed the dog food while blowing the whistle. Eventually, the dog began to associate the whistle with food and salivate when hearing it. 💨 + 🦴→🤤
Conditioned Stimulus (CS)The NS turns into the CS. The CS is what one would learn to respond to. (after conditioning occurs)The whistle is now the CS since the dog began to associate food with the sound of a whistle. 💨→🤤
Conditioned Response (CR)A learned response to a CS. (after conditioning occurs)Salvation to the whistle is the conditioned response. The dog learned and, again, began to associate the sound of the whistle with food, salivating when he hears it. 💨→🤤
AcquisitionWhen the NS and US are linked together so that the NS triggers the CR. Through acquisition, the NS becomes the CS.Before, the whistle triggered no response. However, during conditioning, food and the whistle were linked and now the whistle causes salivation. 🦴→ 💨 which →🤤
ExtinctionWhen the CS no longer causes the CR to happen.Overtime, the dog will learn that there is no food that comes with the sound of the whistle and it stops salivating when a whistle is blown. This is called extinction. 💨→😑
Spontaneous RecoveryWhen the CS suddenly begins to trigger the CR. (randomly after extinction)When the dog starts to salivate at the sound of the whistle after a long time of not doing that. Randomly . . . 💨→🤤
GeneralizationTriggering the CR to a stimulus similar to the CS.The dog begins to salivate when it hears the sound of a whistle and the sound of a bell, even though it isn't conditioned to salivate to the sound of the bell. 💨→🤤 and 🔔→🤤
DiscriminationWhen the CR only occurs to a specific CS.The dog doesn't salivate at the sound of every whistle—it only salivates to the sound of a particular whistle. 🔊💨→🤤

🎥Watch: AP PsychologyClassical Conditioning


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