In omnivores, such as rats and humans, most food preferences are produced by experience. This research aims to understand the learning processes that produce conditioned food preferences. The research concerns how flavors come to be preferred by being associated with already preferred flavors (i.e., sweet) or with nutrients (i.e., calories). We are also concerned with whether merely being exposed to foods increases preference for them and whether subjects learn about taste (i.e., salty, sour, bitter, sweet) and odor stimuli (i.e., flavor extracts) by the same learning processes. The work is of potential practical relevance as well. Understanding how food preferences are learned can lead to strategies aimed at changing food preferences towards more healthy foods, which could prevent obesity, diabetes and other health problems related to types of food consumed. Similarly, understanding how food aversions are learned can assist in the development of behavioral modification strategies aimed at eliminating food aversions to healthy and beneficial foods.