The role of contextual stimuli in the blocking paradigm

Abstract

Two experiments used rats in a conditioned lick-suppression paradigm to investigate the role of contextual stimuli in a traditional blocking paradigm. Experiment 1 demonstrated that the blocking effect could be significantly attenuated by changing contexts between the simple and compound stimulus conditioning phases of the blocking procedure. Experiment 2 demonstrated that the blocking effect could also be attenuated when both phases occurred in the same context as long as substantial context-alone exposure (i.e., extinction) was given between the two training phases. Experiment 2 also showed that the attenuating effects produced by extinguishing the training context could be alleviated if additional footshocks were given in either the training or a novel context, suggesting that context extinction may result in both a weakening of direct context-unconditioned stimulus (US) associations and a degradation of the US memory representation. These findings indicate that contextual associations can play an important role in producing the blocking effect. The potential use of contextual manipulations to distinguish between explanations for blocking deficits shown by animals with hippocampal lesions is discussed. © 1988, Psychonomic Society, Inc.. All rights reserved.