A behavior systems approach to the expression of backward associations

In the first phase of Experiment 1 rats were trained with a backward serial conditioned stimulus (CS) with three 8-s elements (Food-Near-lntermediate-Far, where the name of the element denotes its temporal proximity to food). In the second phase of this experiment, different groups received a novel lever presented in compound with a different CS element. In the first phase of Experiment 2, rats were also trained with a similar backward serial CS; but, in the second phase, the entire serial CS was shifted to a forward pairing (Far-Intermediate-Near-Food), and again different groups received a novel lever in compound with a different CS element. In the first phase of Experiment 3, a serial CS was explicitly unpaired with food. The second phase of this experiment was identical to that of Experiment 2. The results showed that lever contact was lowest during the Near element in Experiment 1, highest during the same element in Experiment 2, and indistinguishable among all the elements in Experiment 3. These outcomes support the behavior systems hypothesis that backward CSs come to control a sequence of post-food search modes that can influence subsequent pre-food search. (C) 1998 Academic Press.