Generalization is the tendency to respond to stimuli that resemble the original conditioned stimulus. Once a response has been learned to a specific cue, similar cues also elicit the response, though usually more weakly.

A child bitten by a particular dog may fear other dogs, or even other animals. A tone paired with food produces salivation not only to that exact tone but to tones of nearby frequencies. The gradient of generalization shows response strength declining as the new stimulus becomes less similar to the original. Discrimination training can sharpen the gradient so that only a narrow range of stimuli remains effective.

Generalization is adaptive. It allows learning to transfer to new but related situations without requiring every instance to be experienced. It becomes maladaptive when the spread is too broad—as in phobias that extend far beyond the original danger. The same principle operates in operant conditioning and in human category learning.

Learning would be of limited use if it applied only to the exact stimulus that was trained. Generalization extends its reach.