Psychology › Learning & behavior › Classical conditioning (Pavlov's dogs)
Extinction: fading a conditioned response
Described 1927· Concept
Well replicatedStrong, repeated evidence.
When a learned signal stops predicting its outcome, the response gradually fades, but it is suppressed, not erased.
See it on the Psychology map →What it says
Pavlov found that sounding the cue repeatedly without food made the dogs' salivation fade; he described this in his 1927 lectures, Conditioned Reflexes. But the old learning survives. After a rest the response can return (spontaneous recovery); it can come back in a new setting (renewal) or after one new pairing. Mark Bouton's research since the late 1970s showed extinction is new learning layered over the old, and tied to context. Operant behavior also fades when rewards stop, often after a brief burst.
Why it matters
It explains why fears and addictions relapse, and why exposure therapy for phobias, PTSD and OCD repeats practice across varied places and cues.
The evidence
Status: well replicated. Pavlov's experiments, thousands of animal studies and human fear-conditioning labs. Brain studies show the prefrontal cortex inhibiting the amygdala's old fear memory rather than deleting it.
Open questions
Whether old learning can ever be truly erased: 'reconsolidation' studies that try to rewrite fears while they are recalled have produced mixed results.
Connections (2)
▸Extinction: fading a conditioned response suppresses responses learned in Classical conditioning (Pavlov's dogs)Well replicated
The connection
Extinction is the flip side of classical conditioning: when the signal keeps appearing without its outcome, the learned response fades. But the original association survives underneath. A new 'this signal means nothing now' memory competes with the old one, and which wins depends on context and time. That is why fears and cravings can return.
Who showed it and when
Pavlov's lab in St. Petersburg, described in his 1927 lectures; Mark Bouton's renewal experiments with rats in the US, from the late 1970s.
The evidence
Spontaneous recovery, renewal and reinstatement are among the most repeated findings in learning research, shown in animals and in human fear-conditioning labs.
Open questions
Whether any procedure can erase the original memory rather than override it; reconsolidation and drug-assisted approaches have produced mixed results in people.
▸Exposure therapy works through Extinction: fading a conditioned responseWell replicated
The connection
Extinction is the lab finding that a learned fear fades when the warning signal keeps arriving without the bad outcome. Exposure therapy applies it: someone afraid of dogs meets calm dogs again and again until the brain learns the cue no longer predicts harm. The old fear is not erased; new safety learning overrides it.
Who showed it and when
Ivan Pavlov described extinction in dogs (published in English in 1927); Joseph Wolpe and later behavior therapists turned it into treatment from the 1950s.
The evidence
Fear extinction works similarly in rats and people and uses the same amygdala and prefrontal circuits; drugs that boost extinction in animals have been tested alongside exposure.
Open questions
Because fear is overridden rather than erased, it can return with time, stress or a new setting; how best to prevent that relapse is an active question.