Papers in the Biological Sciences


Date of this Version



Published in Journal of Comparative and Physiological Psychology 67:3 (1969), pp. 364-369.

PMID: 5787387


Published by American Psychological Association. "This article may not exactly replicate the final version published in the APA journal. It is not the copy of record." Used by permission.


The effects of CS1 duration, partial reinforcement, and trace conditioning on second-order conditioned suppression were investigated, employing 64 rats as Ss. In Experiment 1, the clearest second-order conditioning was obtained when CS1 duration was the same during both the first- and the second-order conditioning phases of the experiment. In Experiment 2, somewhat better second-order conditioning was obtained when first-order conditioning had been under conditions of partial reinforcement, delay CS-US pairing. In neither experiment were CS1 suppression and CS2 suppression during second-order testing well correlated. This aspect of the results raised the question of the influence of nonclassical conditioning factors on the conditioned suppression measure of emotional conditioning.