Does Early Olfactory Exposure Result in an Odor Preference or the Loss of Avoidance?

From Day 5 until Day 14 rat pups were rubbed daily with either acetophenone, ethyl benzoate, or water. Each pup was tested on Day 14 for their olfactory preferences by using four different alleyway odor combinations. The home cage odor was significantly preferred over clean wood shavings and clean shavings plus the familiar odor was significantly preferred over clean shavings plus the novel odor. The familiar odor alone was not preferred over clean shavings nor was the home-cage odor preferred over the odor of another litter's cage odor. It is suggested that with artificial odors pups are much more likely to prefer a familiar artificial odor when it is compared with a novel odor than when the familiar odor is paired with a neutral odor.