Pavlov's dogs were conditioned to salivate to a 1000-hz tone due to its pairing with food. after this training, it was found that the dogs would salivate to a 900-hz tone but not to a 500-hz tone. salivating to the 900-hz tone is an example of and not salivating to a 500-hz tone is an example of

generalization; discrimination    

Explanation:

Generalization and Discrimination are the terms being used in classical conditioning.

Generalization: In psychology, it is defined as the propensity to acknowledge in the same way to different but alike stimuli.

Discrimination: In psychology, discrimination is defined as the ability to recognize and respond to dissimilarity among stimuli.

Example:

conditioned stimulus - bell tone.

discrimination - Difference between similar sound and bell sound.