Acquired relational equivalence: Implications for the nature of associative structures

In 2 experiments, rats received iscrimination 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 ofC and D signaled a different pair of relationships (X ~ no food and Y--- * food). To assess the nature of the associative structures acquired uring this training, rats then received 2 types of revaluation 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 revaluation treatment, rats showed greater generalized conditioned suppression i the presence of B than D. These results indicate that A, B, C, and D come to evoke memories of the relationships or associations that hey have signaled. Animals can acquire discriminations in which the pres-ence or absence of any single conditioned stimulus (CS) provides no information regarding whether or not an uncon-ditioned stimulus (US) will be delivered. For example, in a biconditional discrimination, the presentation of some com-binations of CSs (A-X and B-Y) signal that a US will be delivered, whereas that of others (A-Y and B-X) signal tha