Olfactory learning and odor memory in the rat.

Rats were trained on a series of 9 tasks, each of which required discrimination among 8 different and unique odors. Discrimination accuracy improved across successive problems and, by the end of training, most rats made few errors after their initial exposure to each new odor. Despite the number of stimuli to be discriminated, this acquisition of a learning set was not appreciably different from that demonstrated in an earlier study that used only 2 odors per task. In subsequent retention tests, most rats also showed excellent memory for odors used in prior problems.