Prospective memory involves the encoding, retention, and implementation of an intended
future action. Although humans show many forms of prospective memory, less is known
about the future oriented processes of nonhuman animals, or their ability to use prospective
memory. In this experiment, a chimpanzee named Panzee, who had learned to associate
geometric forms called lexigrams with real-world referents, was given a prospective
memory test. Panzee selected between two foods the one she wanted to receive more
immediately. That food was scattered in an outdoor yard where she could forage for it. Also
outdoors were lexigram tokens, one of which represented the food item that remained
indoors throughout a 30 min period, and that could be obtained if Panzee brought in the
token that matched that food item. After foraging for the selected food item, Panzee consistently
remembered to retrieve and return the correct token when food was available
indoors, whereas on control trials involving no indoor food she rarely returned a token. This
indicated that Panzee encoded information relevant to the future action of token retrieval
after extended delays for one type of food, even when a more immediately preferred food
was available.