The existence of primacy and recency effects in nonspatial recognition memo
ry in rats was investigated using a nonmatching-to-sample task (namely, vis
ual discrimination in a Y-maze). Although previous research has demonstrate
d recency effects in nonspatial tasks, evidence for a primacy effect in suc
h tasks is equivocal. The current study evaluated nonspatial memory under c
onditions that have been found to optimize primacy effects. Significant pri
macy effects were found over all trials and also for the last six trials. R
esults are discussed in terms of identification of the optimal conditions f
or producing and detecting serial position effects in memory. (C) 2000 Acad
emic Press.