tors while they view the same events directly, they are likely to "discover" that monitors can portray parts of the world that they otherwise cannot see (Bloomsmith 1989). For example, chimpanzees can garner important information from video monitors about the locations of foods and incentives and about the course of activities in areas beyond their view (Menzel and others 1985). Chimpanzees can come to prefer watching specific video-taped recordings, especially those of other chimpanzees they know, but there is little reason to believe that they profit from watching ordinary television programming other than nature films on conspecifics. They might attend to programs showing vigorous human interactions, such as dancing and sports (e.g., wrestling, boxing, and football) (D.M. Rumbaugh, unpublished data). Providing television sets for animals in laboratories and on exhibit has a certain appeal to humans, but benefits to the animals are dubious.
Despite their impressive cognitive abilities and interest in a wide variety of puzzles and cognitive challenges, there is as yet no way to assess a "need" for intellectual exercise in great apes. Ordinary social living in a well-designed enclosure might provide chimpanzees and other great apes all the intellectual stimulation that they require. Although attempts at enrichment should certainly be directed at singly caged animals in restricted environments (Nadler and others 1992), those in social groups also benefit greatly from an enriched environment.
Caregivers should be sensitive to apes as individuals. Apes often do not trust unfamiliar people, so new caregivers should be introduced systematically and gradually. In this way, both humans and apes learn what to expect from one another, and experienced personnel recognize the needs of their charges (Baker 1997). Feeding time is a very important time of day, and feeding practices should be such as to encourage caregiver-animal communication. Feeding and cleaning practices can serve to establish good relationships between caregivers and apes that, in turn, enrich the apes' lives and also inform the caregivers regarding the animals' behavior and physical condition.
Not only should personnel be trained and experienced in the behavior of apes, but it is imperative that they be trained in safety. Great apes are very powerful, active, and sometimes devious. Primates in general will harm people only in defense or in reaction to a threat, but a chimpanzee's aggressive actions are unpredictable and often seem premeditated. Such serious injuries as loss of fingers, bite and scratch wounds, and lacerations have been suffered by people working with apes. Chimpanzees should be treated with respect throughout their development. They have long memories and will recognize a favored or disfavored human after several years of separation.
Personnel should be continually reminded of established safety procedures. Cages should be designed to prevent the apes from reaching outside the cage.