The role of oral and postingestional cues in the conditioning of taste preferences based on differing caloric density and caloric outcome in weanling and mature rats

Experiments 1, 2, and 3 demonstrated that 23-day-old rat pups can acquire a conditioned taste preference for a flavor paired with either a more calorically dense diet or a diet that provides more calories than another diet of equal caloric density. Experiment 4 showed that 42–49-day-old rats also can acquire conditioned taste preferences based on differing caloric density and differing caloric outcome. Experiments 5 and 6 demonstrated that adult rats form conditioned taste preferences based only on caloric density. Although these experiments indicate that young rats are apparently capable of more diverse learning than adult rats, the question of what US underlies conditioned taste preferences based on diets of differing caloric density remains unresolved.