Tuesday, August 06, 2002


Chronicle of Higher Education
August 9, 2002
Pretenders in the Mist?
Scientists debate whether apes play make-believe

Viki impersonates her adoptive mother. She pushes around the vacuum cleaner, files her fingernails, and smoothes on lipstick with a finger. Though she cannot read, she opens the newspaper every morning and turns the pages one by one, examining some as though she has found an interesting article. If Viki were a child, her parents would say she was pretending. But she may just be aping what she's seen: Viki is a chimpanzee.

Scientists disagree about whether those behaviors and others observed in great apes, both in captivity and in the wild, are true examples of pretending. Does Viki imagine she's someone else, or is she merely going through the motions of behaviors she knows well or has observed in others?

Children enact elaborate fantasies, and researchers, who have been probing that pretend play for more than 100 years, still debate what mental processes are involved. But scientists have been slow even to look for examples of pretending in animals, for fear of being considered "loopy," says Robert W. Mitchell, a psychology professor at Eastern Kentucky University and the editor of Pretending and Imagination in Animals and Children (Cambridge University Press, April). Dolphins, parrots, and elephants have exhibited some behaviors that look like pretending, but Mr. Mitchell says that only researchers who work with primates were willing to contribute to the book. "People are afraid for their careers if they talk about this," he says. "If we're avoiding using certain terms that are accurate, that's a problem."

Part of the difficulty of determining whether apes pretend is that researchers define the word in various ways --depending, for example, on whether an animal seems to mimic another animal's behavior immediately after seeing it or hours later, in a different context. But scientists generally agree that pretending means imagining that something is other than it really is. It can involve behaviors like deliberately responding as if to a stimulus when none exists, acting as if doing one thing while actually doing something else, or using an object as though it were something else. A pretender must simultaneously hold two representations of the situation in mind --the actual one and the imagined one.

The most compelling examples of possible pretending come from animals [who] have been brought up by humans, like Viki. Researchers studying a gorilla named Koko, who was taught to use sign language at the Gorilla Foundation, in Woodside, Calif., cite dozens of behaviors that they interpret as make-believe. Koko plays with dolls, nursing them, talking to them, and making them interact with each other. Handed a strawberry stem, Koko puts it on the head of an alligator toy and says, "hat." In another example, Koko points to a photograph of the enormous, wide-open mouth of a hippopotamus in a calendar. She then folds the calendar and puts it in her mouth, creating her own huge "lips."

Enculturated apes like Koko and Viki seem to pretend more frequently than do apes in the wild. While Koko's handlers see behaviors they interpret as pretending practically every day, Anne E. Russon, an associate professor of psychology at York University, in Toronto, says she has found in the literature only about 20 cases of possible pretending in free-ranging orangutans, culled from thousands of hours of observation. One reason is that researchers haven't been looking for such behavior, she says in an e-mail interview from her field station in Borneo. But many researchers believe that interaction with humans --and the encouragement to pretend that comes with it --may play a major role in why enculturated apes play-act more.

Orangutan Fake-Out

Wild apes don't have lipstick and newspapers to play with, but they have exhibited behavior suggesting that they, too, pretend. Ms. Russon videotaped Unyuk, an orangutan living in a park in Indonesian Borneo for apes recovering from injuries, playing with a human friend whose backpack was often full of food. Even though she spied the backpack, Unyuk innocently continued the game without looking toward it, occasionally shifting position slightly. When she had moved enough that her friend was no longer between her and the backpack, Unyuk lunged for it, taking her playmate by surprise.

Ms. Russon also watched one young wild orangutan, Paul, intentionally deceive another in a successful effort to get at food. Paul watched Bento, whom he normally feared and avoided, eating Paul's favorite food, forest coconut palm. Suddenly, Paul darted out in front of Bento, who chased him. Paul led Bento to a stash of papaya and later crept back to eat Bento's coconut-palm leftovers. Ms. Russon argues that Paul was concealing his interest in the palm and then acting as his own decoy to get Bento away from it.

"Most of the published evidence concerns captive great apes," says Ms. Russon, but "these abilities are also obvious and have an important function in the wild. They're not simply laboratory artifacts."

But some scientists remain unconvinced that apes pretend. In one chapter of Pretending and Imagination in Animals and Children, Juan Carlos Gmez, of the University of St. Andrews, in Scotland, and Beatriz Martn-Andrade, of the Autonomous University of Madrid, analyze several possible examples of gorillas pretending at the Madrid Zoo. In every case, they find other explanations for the behavior, and they conclude that it is less cognitively sophisticated than true pretending.

In one example, two young female gorillas treated stones, balls, and a doll as if they were infants, carrying the objects on their backs or held against their chests with one arm. Though those actions could be pretending, Mr. Gmez and Ms. Martn-Andrade argue that a simpler and likelier explanation is that the apes were behaving instinctively with substitute objects, without thinking of those objects as babies.

In another example, a young gorilla named Muni was working with a trainer. When Muni performed correctly, the trainer would give her jam on a spoon. But several times, instead of eating her reward, Muni put another spoon in the jam and stirred it, then pointed it toward the trainer's mouth. The authors point out that gorillas often put things --not always food –in humans' mouths, and argue that Muni might have been thinking of herself as acting instead of the trainer, not as if she were the trainer.

Another scholar who contributed a chapter to the book, Ellen J. Ingmanson, an assistant professor of anthropology at the College of William and Mary, says Mr. Gmez is being "overcautious." Mr. Mitchell, the editor, says that Muni may actually have been pretending, but that Mr. Gmez "wants more evidence, and so do I."

Not 'Just Like Us'

Other researchers, too, are unsatisfied with the evidence. "Anybody who says that they know what the answer is obviously hasn't confronted the deep problems in the area," says Daniel J. Povinelli, a professor of cognitive science at the University of Louisiana at Lafayette. Not enough systematic observational data have been collected, he argues. "I don't see any compelling evidence that chimpanzees or any other great apes engage in what we would call pretend play in children."

"What it definitely shows is what humans are capable of imagining these animals are doing." Marc Bekoff, a professor of biology at the University of Colorado at Boulder, agrees with the call for more research on primate behavior. Apes may have developed their own type of pretending, he says, "but surely it's not the same as human pretense." He argues that the reason researchers have so few examples of apes' pretending in the wild --apart from not having done enough observation --is that to survive, apes don't need to pretend, in the sophisticated sense of holding two conceptions of a situation in mind at once. "It would be really anthropocentric to think that other animals are just like us," he says.

Yes, says Sarah T. Boysen, a professor of psychology at Ohio State University at Columbus and a chimpanzee researcher, but great apes are pretty closely related. Are they capable of sophisticated pretending? "Absolutely," she says. "The cognitive capacities of chimpanzees are likely dramatically underestimated. It's just our limitations of finding ways to measure them."

Until researchers can produce more evidence, they will continue to debate whether apes really pretend or just monkey around.