What is it called when a conditioned stimulus loses its effect over time?

Spontaneous recovery refers to the sudden reappearance of a previously extinct conditioned response after the unconditioned stimulus has been removed for some time.

This phenomenon can occur after these two types of conditioning have taken place.

Classical conditioning – involuntary learning process through the association of neutral stimulus with a biologically potent stimulus that produces an unconditioned response.

Operant conditioning – voluntary learning through the use of reinforcement and punishment.

Spontaneous Recovery Examples – Classical Conditioning

In classical conditioning, also known as pavlovian conditioning, a previously neutral stimulus (NS) becomes conditioned when it is repeatedly paired with the unconditioned stimulus (US). This now conditioned stimulus (CS) can produce its own conditioned response (CR), which is usually very similar to the unconditioned response (UR).

However, some conditioned responses are vulnerable to extinction. If the conditioned stimulus continues to appear in the absence of the unconditioned stimulus, the conditioned response becomes weaker and weaker until it disappears, which is called the extinction procedure.

A famous example is Pavlov’s dogs. Ivan Pavlov, who coined the term pavlovian conditioning, experimented by sounding a bell repeatedly when he fed the dogs. Over time, they learned to associate the sound with food and salivated (a learned behavior) when they heard the sound. Then Pavlov started ringing the bell without giving food. Eventually, the dogs stopped salivating to the sound of the bell.

However, Pavlov noticed that even after a substantial amount of time had passed, the conditioned response would easily recover if the neutral stimulus and the unconditioned stimulus were paired again one day. Even though the dogs stopped salivating to the sound of the bell, their salivation recovered spontaneously after a “rest period.”​1​

Another example is that a child gets excited every day when they hear the ice cream truck music because their mother always buys them ice cream. When their mother stops buying, the child gradually learns to not associate the ice cream truck music with eating ice cream. After the truck stops coming for a few days and then returns, the child gets excited again when they hear the truck music.

Spontaneous Recovery Examples – Operant Conditioning

A trainer teaches a dog to sit by associating the command “Sit” with food. So the dog learns to sit whenever the trainer says the word. But after the trainer stops giving it food, the dog gradually stops responding to the command. Days later, the trainer tries again, and the dog sits again.

Here is another example. A child runs to the door to greet Dad because he always brings home a new toy. After Dad stops bringing home toys, the child stops running to the door to greet him. After a few days, the child suddenly resumes to greeting their Dad at the door.

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How It Works

Extinction involves inhibition.

The fact that conditioned response can suddenly recover suggests that extinction doesn’t erase the learned association. Instead, extinction inhibits the conditioned response. It appears that extinction forms new learning separate from the original conditioned learning​2​.

This new learning “extinguish” the conditioned response by inhibiting its expression instead of erasing or unlearning it. The conditioned response has not been forgotten or eliminated. Since the initial conditioned response never disappears, it eventually returns.

For example, studies show that, with sufficient time, sudden recovery of the fear response after extinction occurs 100% in situations such as fear conditioning​3​.

Recovery increases over time.

Over time, the inhibition from extinction fades and the spontaneous recovery gradually increases with time.

During the recovery, memory from the extinction process competes with the reactivated memory from initial conditioning but fails​5​.

Since new learning does not replace old ones, spontaneous recovery does not replace the extinction learning either. The recovery simply exists in the presence of extinction learning​4​.

Spontaneous recovery is incomplete

The strength of the recovered learning is usually smaller than the original learning. If extinction is applied again, the subsequent recovery will become weaker and weaker.

References

About Pamela Li

Pamela Li is a bestselling author. She is the Founder and Editor-in-Chief of Parenting For Brain. Her educational background is in Electrical Engineering (MS, Stanford University) and Business Management (MBA, Harvard University). Learn more

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