Most of the literature in psychology and physiology that deals with feeding in animals and humans focuses on hunger or how much is eaten (the regulation of food intake) rather than what is eaten (the selection of foods). Motivation textbooks rarely elaborate on the determinants of food selection, and if they do, such discussions occur in the section on hunger. The fact that food habits are used in the naming of higher-level taxonomic groups (e.g. carnivores, herbivores or omnivores, etc.) supports the notion that food selection is a major force in evolution. The prominence of food selections in our daily life is also evident amongst humans. If animals and humans are to survive and reproduce in their environments, they must find and eat foods that provide all the nutrients necessary for self-maintenance and reproduction, as well as to avoid eating lethal amounts of toxic plants or animals that they encounter.

This chapter describes and discusses the mechanisms that explain how animals and humans manage to discriminate foods containing needed nutrients from ingestible sources that are either valueless or dangerous to eat. The other major issue concerns the tendency amongst humans to be selective in their acceptance of a small subset of many edible items that are available to them. Explanations of these two major issues will be accomplished by a discussion of built-in ‘hardware and software programmes’ cognitive or learning processes and socio-cultural factors (mainly in humans) which are responsible for the choice of foods.