Classical Conditioning
Bell presented without meat many times.
Bell elicits no salivation.
Phase IV: Extinction Phase
Pavlov observed that a previously learned response (CR) was eliminated by repeatedly presenting the CS without presenting the UCS. When extinction occurred, the CS was no longer capable of producing the CR (salivation). Zimbardo and Gerrig (1999) explained that extinction happens when the CS no longer predicts the UCS.
Here Today, Gone Tomorrow, Back Again!
After the CS (bell tone) has been presented several times without any food forthcoming, the dog's salivation response extinguished and the dog stopped salivating to the CS (bell tone) alone. However, if the CS is not presented for a period of time and then is presented, the previously learned conditioned response of salivation on hearing the tone alone will return. The dog is displaying spontaneous recovery of the response but may not salivate as much as it did when it was first classically conditioned to the CS (bell tone).
A feature of the Extinction Phase is Spontaneous Recovery which means that the Conditioned Response reappeared after the Conditioned Response had been previously eliminated. Kosslyn and Rosenberg (2003) explained that when a Conditioned Response has been extinguished, the Conditioned Stimulus will again elicit the Conditioned Response, although sometimes not as strongly as before extinction.