Generalization Gradients and Combined-Stimulus Control after Equal Training Wit! Two Related Stimuli: II. Effects of “Errorless” Training. III. Effects of Chlorpromazine

Abstract

For 2 groups of pigeons, each of two differentially positioned stimulus lamps were correlated with identical reinforcement schedules, and the absence of both lamps signalled extinction. Key-pecking responses of one group were brought under stimulus control by a procedure which initially resulted in many “errors.” The second group’s responses were brought under control by a “fading” procedure, and few errors occurred. In Exp. I both the intermediate stimulus and the combined stimuli controlled higher response rates than the single training stimuli, and other stimuli controlled lower rates. In Exp. II, chlorpromazine reduced responding during the stimuli correlated with reinforcement but had no effect on responding during the stimulus signalling extinction. The occurrence of errors in the acquisition of stimulus control was not a necessary condition for the observation of enhanced control by intermediate and combined stimuli nor a sufficient condition for the disruption of control by chlorpromazine.