Review

Orienting is one of the most primitive functions of living things. Even the leaves of a plant orient towards sunshine; the roots towards moisture. In more complex organisms more complex systems have evolved to orient the various receptors reflexively either towards or away from signal sources in the environment and to prepare the organism to select from a repertoire of behavioral actions1. Whereas the efficiency and rapidity provided by reflexive control of orienting would be critical in predation and defense, voluntary control over the orienting reflexes has undoubtedly been an important evolu-tionary development. Efficient foraging for food (or other desirable objects, places, playmates) involves not only volun-tary control over orienting but also the use of information stored in memory about one’s previous orienting behavior. Once discovered, the locus of a food source that is not exhausted should be remembered as a place to return to. By contrast, places one has searched and not found what one is looking for, or places that have been stripped bare, should be remembered to be avoided. A mechanism that encourages orienting towards novel locations would be useful in these Inhibition of retur