1) An opportunity for a response or some other event, or the circumstances under which a contingency operates, as when discriminative stimuli set the occasion on which responses have some consequence. When a stimulus is said to occasion a response, the term serves as a verb and distinguishes responses emitted in the presence of discriminative stimuli from those elicited by stimuli in a reflex relation.

2) To increase the likelihood of the emission of a response by arranging prior. stimulus conditions. Also used as an action verb in reference to operant behavior, where the response bears a probabilistic relationship (not a one-to-one relationship, as with elicit) to the occurrence of the SD. The terms set the occasion for, evoke, promote, cue, and signal may serve as synonyms.