What did Pavlov call the return of a previously extinguished conditioned response following a rest period?

Spontaneous recovery is a phenomenon that involves suddenly displaying a behavior that was thought to be extinct. This can apply to responses that have been formed through both classical and operant conditioning.

Spontaneous recovery can be defined as the reappearance of the conditioned response after a rest period or period of lessened response. If the conditioned stimulus and unconditioned stimulus are no longer associated, extinction will occur very rapidly after a spontaneous recovery.

Spontaneous Recovery Examples

Even if you are not familiar with much of psychology's history, you have probably at least heard of Ivan Pavlov's famous experiments with dogs. In Pavlov's classic experiment, dogs were conditioned to salivate to the sound of a tone.

The sound of a tone was repeatedly paired with the presentation of food. Eventually, the sound of the tone alone led the dogs to salivate. Pavlov also noted that no longer pairing the tone with the presentation of food led to the extinction, or disappearance, of the salivation response. So what would happen if there was a "rest period" where the stimulus was no longer present?

Pavlov found that after a two-hour rest period, the salivation response suddenly reappeared when the tone was presented. Essentially, the animals spontaneously recovered the response which was previously extinct.

For another example, imagine that you have used classical conditioning to train your dog to expect food whenever he hears the ding of a bell. When you ring the bell, your dog runs to the kitchen and sits by his food bowl. After the response has been conditioned, you stop presenting food after ringing the bell.

Over time, the response becomes extinguished, and your dog stops responding to the sound. You stop ringing the bell altogether, but a few days later you decide to try ringing the bell again. Your dog rushes into the room and waits by his bowl, exhibiting a perfect example of spontaneous recovery of the conditioned response.

How Spontaneous Recovery Works

In order to understand exactly what spontaneous recovery is and how it works, it is essential to begin by understanding the classical conditioning process itself. How does classical conditioning take place?

Classical conditioning involves forming an association between a neutral stimulus and an unconditioned stimulus that naturally and automatically produces a response. Flinching in response to a loud sound or salivating in response to the smell of dinner cooking in the oven are both examples of unconditioned stimuli.

Your response to these things takes place automatically without any learning, which is why it is referred to as the unconditioned response. After repeatedly pairing something with the unconditioned stimulus, the previously neutral stimulus will begin to trigger the same reaction, at which point it becomes known as a conditioned stimulus. The learned reaction to the conditioned stimulus is now referred to as the conditioned response.

For example, in the famous Little Albert experiment, researchers John B. Watson and Rosalie Rayner repeatedly paired a loud sound (the unconditioned stimulus) with the presentation of a white rat (the neutral stimulus). The child in their experiment was previously unafraid of the animal but naturally frightened by the loud noise (the unconditioned response).

After multiple pairing of the noise and the sight of the rat, the child eventually began to display the fear response (now known as the conditioned response) whenever he saw the white rat (the conditioned stimulus). So what might have happened if Watson and Rayner had stopped pairing the rat and the noise?

At first, the child would naturally still be quite frightened. After multiple instances of seeing the animal without any noise present, the child’s fear would likely start to dissipate slowly and eventually he might have even stopped displaying the fear response.

Why Spontaneous Recovery Is Important

But if a conditioned response becomes extinguished, does it really disappear altogether? If Watson and Rayner had next given the boy a brief rest period before reintroducing the rat, Little Albert might have exhibited a spontaneous recovery of the fear response. Why is spontaneous recovery so significant?

This phenomenon demonstrates that extinction is not the same thing as unlearning. While the response might disappear, that does not mean that it has been forgotten or eliminated.

After a conditioned response has been extinguished, spontaneous recovery may gradually increase as time passes. However, the returned response will generally not be the same strength as the original response unless additional conditioned takes place.

Numerous cycles of extinction followed by recovery usually result in progressively weaker responses. Spontaneous recovery may continue to take place, but the response will be less intense.

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1. Spontaneous recovery. APA Dictionary of Psychology.

2. Rehman I, Mahabadi N, Rehman CI. Classical Conditioning. Treasure Island (FL): StatPearls Publishing;2020.

3. Watson J, Rayner R. Conditioned emotional reactions. American Psychologist. 2000;55(3):313-317. doi:10.1037/0003-066x.55.3.313

Additional Reading

• Schacter, D.L., Gilbert, D.T., & Wegner, D.M.  Psychology. New York: Worth Publishers; 2011.

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