Relative Novelty Does Not Explain Primacy Effects in Rats' Memory for Serially Presented Novel Flavors

Abstract

Three experiments examined the effect of sequential exposure to a series of five novel flavors on the subsequent neophobic response of water-deprived rats to those flavors, when the flavors subsequently were presented simultaneously to the rats. During the test phase of all experiments, rats consumed more of the first and last flavor presented in the initial list than of those flavors presented in the middle of the initial sequence. This was taken to reflect the existence of primacy and recency effects. The rats also were presented with additional lists of novel, five-flavor sequences (two in Experiments 1 and 3, and three in Experiment 2). If primacy effects were due to the distinctiveness of the first item, engendered since it was also the first novel flavor experienced by the rats, then primacy would not be expected after exposure to subsequent series of flavors. In fact, a primacy effect was noted on every exposure, whether subsequent exposures to novel sequences occurred 24 h or 48 h after the first exposure. These results suggest that relative novelty was not responsible for the observed primacy effect.