  Classical associationism relied on introspectible entities, such as perceptual experiences or stimulations as the first links in associations, and thoughts or ideas as the second links. Psychological behaviorism, motivated by experimental interests, claims that to understand the origins of behavior, reference to stimulations (experiences) should be replaced by reference to stimuli (physical events in the environment), and that reference to thoughts or ideas should be eliminated or displaced in favor of reference to responses (overt behavior, motor movement). Psychological behaviorism is associationism without appeal to inner mental events.