Different mechanisms for social transmission of diet preference in rat pups of different ages.

We examined the role of simple exposure to a diet in the development of preference for that diet in rat pups 21, 28, 38, and 45 days of age. We found: that 21-day-old rat pups exhibited a preference for a diet to which they were simply exposed for 30 min; that 28-, 38-, and 45-day-old pups failed to exhibit simple-exposure induced preference for a diet; and that pups at all ages examined, exposed for 30 min to an anesthetized conspecific whose face had been dusted with a diet, subsequently exhibited a preference for that diet. We interpreted these data as indicating that socially-induced diet preference in 21-day-old pups can be explained by effects of simple exposure, while socially-induced diet preference in older rats cannot. Pups older than 21 days of age appear more sensitive to the social context in which diet-identifying olfactory cues are experienced than do 21-day-old pups.