In the first phase of Experiment 1 rats were trained with a backward s
erial conditioned stimulus (CS) with three 8-s elements (Food-Near-lnt
ermediate-Far, where the name of the element denotes its temporal prox
imity to food). In the second phase of this experiment, different grou
ps received a novel lever presented in compound with a different CS el
ement. In the first phase of Experiment 2, rats were also trained with
a similar backward serial CS; but, in the second phase, the entire se
rial 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 du
ring the same element in Experiment 2, and indistinguishable among all
the elements in Experiment 3. These outcomes support the behavior sys
tems hypothesis that backward CSs come to control a sequence of post-f
ood search modes that can influence subsequent pre-food search. (C) 19
98 Academic Press.