Short-term exposure to an odor increases its subsequent preference in preweanling rats: a descriptive profile of the phenomenon.

Five experiments assessed the change in preference for an ambient odor after a brief period of exposure to that odor. Three minutes of exposure to a novel odor consistently increased subsequent preference for that odor. This effect occurred in preweanling rats 10 and 15 days of age even though, relative to the nest, the conditions of exposure were probably aversive tactually and thermally. There was relatively little variation in this effect between the ages of 10 Days postnatal and adulthood and over exposure durations ranging between 3 and 81 min. Substantial retention of this exposure effect was found for the 10-day-old rat, with no decline in induced preference over a 24-hr period. The effect was unchanged by brief familiarization with the testing situation, but was eliminated by prior aversive experience with the testing situation. These results have implications for the design and interpretation of experiments that test learning and memory of odors, and emphasize generally the facility of the developing rat for processing olfactory information.