Final answer:
As a stimulus increasingly differs from the conditioned stimulus, the conditioned response becomes weaker and eventually may not occur.
Step-by-step explanation:
According to the stimulus generalization gradient, as the stimulus becomes increasingly different from the original conditioned stimulus, the conditioned response tends to diminish. When an organism, such as a dog or cat, has been conditioned to respond to a certain stimulus through classical conditioning, and that conditioned stimulus is gradually altered or replaced by stimuli that only resemble the original stimulus, the organism's conditioned response becomes weaker. This weakening response occurs because the organism starts to notice differences between the original conditioned stimulus and the new, altered stimuli.
For example, if a dog has been conditioned to salivate to the sound of a bell that signals food, it might still show a conditioned response to a different tone that is very similar to the bell. However, as the tone becomes more and more dissimilar to the conditioned bell sound, the dog's salivation response will gradually weaken and may eventually disappear if the tone becomes too unrelated.