Rats' memory for serially presented flavors: Effects of interstimulus interval and generalization decrement

In four experiments, the effect of sequential exposure to a series of five novel flavors on the subsequent neophobic response of water-deprived rats t o those flavors when they were presented simultaneously was examined. After a list-test interval of 30 min and a list-interstimulus interval of 10 sec . the rats generally consumed more of the first and last flavors presented in the initial sequence. This finding was taken to reflect the existence of primacy and recency effects. Experiment 1 provided evidence that successiv e contamination can occur between flavors in the initial list, making subse quent recognition of later flavors in the list more difficult. However, thi s effect was overcome by presentation of water between each flavor during t he list exposure. Experiments 2 and 4 showed that primacy was not a necessa ry result of successive contamination in this procedure, by demonstrating t hat increasing the interstimulus interval between list items decreased the size of the primacy effect. This result suggests that rats' memory for seri ally presented items may be controlled by mechanisms different from those t ypically implicated in the human verbal memory literature. In Experiment 3? the question of whether the testing procedure adopted here could have intr oduced sources of artifactually produced serial-position effects was explor ed, but no such influence was found.