Acquired relational equivalence: implications for the nature of associative structures.

In 2 experiments, rats received discrimination training in which separate presentations of A and B signaled a common pair of relationships or associations (X-->food and Y-->no food), whereas presentations of C and D signaled a different pair of relationships (X-->no food and Y->food). To assess the nature of the associative structures acquired during this training, rats then received 2 types of reevaluation procedure: In Experiment 1, A was paired with shock and C was not. In Experiment 2, the relationships that A and B had previously signaled (X-->food and Y-->no food) were paired with shock, whereas those that C and D had signaled (Y-->food and X-->no food) were not. After both types of reevaluation treatment, rats showed greater generalized conditioned suppression in the presence of B than D. These results indicate that A, B, C, and D come to evoke memories of the relationship or associations that they have signaled.