Final answer:
The phenomena of the conditioned stimulus losing its ability to elicit the conditioned response when repeatedly presented without the unconditioned stimulus is known as extinction.
Step-by-step explanation:
When a conditioned stimulus is presented without an accompanying unconditioned stimulus, extinction will soon take place.
Extinction occurs as part of the classical conditioning process when the conditioned stimulus (like the sound of an ice cream truck) is repeatedly presented without the unconditioned stimulus (such as the taste of ice cream). Over time, the learned association diminishes, and the organism's conditioned response (like salivating) to the conditioned stimulus weakens and eventually disappears.
This process was extensively studied by Ivan Pavlov through his experiments with dogs. In Pavlov's experiment, the dogs, which had been conditioned to salivate at the sound of a tone when it was paired with food, eventually stopped salivating when the tone was sounded repeatedly without food being presented.