The observation of similar functional relations under Pavlovian and operant contingencies could support the idea that both respondent and operant behaviors are the result of the same process. The effects of the sequence of exposure to non-contingent and contingent water delivery on the occurrence, temporal distribution, and behavioral adjustment were assessed. Lights or tones were used as ... [Show full abstract] antecedent stimuli between subjects. The required responses under each condition of water delivery (nose-poking and lever-pressing) increased and decreased in correspondence with the ongoing contingency. No differences in the temporal distribution of both responses were observed when they were required by the ongoing contingency. Under both sequences of exposure the behavioral adjustment was higher in the second than in the first condition of water delivery. The results are discussed considering the possibility of a single behavioral process under both conditions of water delivery. © 2015, Fundacion para el Avance de la Psicologia. All rights reserved.