Three experiments examined the effects of complete removal of reinforcement and of the introduction of a novel stimulus on conditioned approach and withdrawal behavior exhibited by pigeons in an autoshaping paradigm. Experiment 1 indicated that complete omission of food from the experimental situation resulted in the gradual disappearance of both approach and withdrawal behavior in subjects that had received either explicitly paired or explicitly unpaired conditioning. Subsequent presentation of a novel visual stimulus reinstated both approach and withdrawal. Experiment 2 replicated these findings in a within-subjects, discriminative paradigm. In Experiment 3, presenting the novel visual stimulus during acquisition when approach and withdrawal behaviors were asymptotic did not produce significant disruption of performance. These data suggest that removal of reinforcement leads to the disappearance of withdrawal as well as approach performance, and that subsequent presentation of a novel stimulys reinstates whatever behavior was dominant prior to extinction—a finding that seems analogous to results of experiments concerning proactive interference.