Smithsonian National Zoological Park l Friends of the National Zoo



What Are You Thinking?

Researchers at the National Zoo's Think Tank delve into the minds of primates.


by Cindy Han

It’s a question that has long perplexed and fascinated philosophers, psychologists, and parents of teenagers: How do our minds work? Perhaps we can’t answer that question entirely, but researchers are trying to better understand the processes that make up human intelligence. And one way to determine what makes the human mind unique is by studying the minds of our primate relatives. Scientists at the Smithsonian National Zoo’s Think Tank are looking closely at how great apes like gorillas and orangutans think in order to better understand ourselves. And they’re letting Zoo visitors watch the research in action.

Francys Subiaul and orangutan Kiko
Scientist Francys Subiaul wants to know how other primates, like Kiko, think. (Mehgan Murphy/NZP)

“Think Tank was originally conceived for this purpose,” says National Zoo primate curator Lisa Stevens. “It was developed as an exhibit that would introduce the concept of animal cognition to visitors. Now we have researchers Francys Subiaul and Chikako King bringing science to life at Think Tank. The goal is to give people an appreciation that animals do think, and to bridge the distance between other animals and us.”

Monkey See, Monkey Do

When a baby starts to use a spoon to eat, a parent usually demonstrates the basics: hold handle, scoop, move food to mouth. Even if strained peas end up all over the place, we humans are able to pass along the skill with little conscious thought to the multiple physical and mental processes involved. First of all, there’s spatial judgment—knowing where the spoon, the food, and the mouth are in relation to one another. There’s also imitation—can Junior follow the steps Mom’s taking? And there’s memory—will he be able to repeat the motion the next time, or the next day?

All of these elements make up “social learning,” which is one way we learn from one another. Whether we’re using a spoon or speaking a language, humans tend to take social learning for granted. But to evolutionary psychologist Francys Subiaul, social learning is a key element of what makes the human mind unique.

Subiaul wants to shed light on which aspects of human intelligence are shared with other primates. An assistant professor at George Washington University (GWU), Subiaul recently received a $400,000, five-year grant from the National Science Foundation to conduct cognitive research at the National Zoo. At GWU, his research focuses on how young children process social information, including knowledge acquired from others. But Subiaul needs a point of comparison in order to determine what is unique about human intelligence. That’s why he’s been hanging out with the great apes at the National Zoo’s Think Tank.

What happens when a young ape wants to extract some termites from a mound? Does it learn to use a tool to get its lunch the same way a baby learns to use a spoon? If the ape picks up cues from the others on how to poke a stick into a hole and pull out some bugs, it has engaged in social learning. What Subiaul wants to know is how that learning occurs. His research focuses on how apes approach the processes that make up social learning, such as memory and spatial understanding.

Testing … One, Two, Three

To do this, he conducts a series of experiments—or “imitation tasks”—by putting the apes in front of a computer touch screen. He has a specially designed apparatus that allows him to display images on the screen facing the animal, while he can interact via a second computer on the other side.

Orangutan in cognitive study

Some of the Zoo’s orangutans have already participated in cognitive research studies. (Jessie Cohen/NZP)

Subiaul studies the Zoo’s western lowland gorillas (Gorilla gorilla gorilla) and orangutans (Pongo pygmaeus, Bornean, and Pongo abelii, Sumatran), both closely related to humans, but slightly different in their behavioral patterns.

Say the research participant is Bonnie, an older female orangutan, who is a veteran of these types of studies (see “Brainy Bonnie" link, upper left). Subiaul sits on one side of the computer outside the enclosure, while Bonnie faces the touch screen. Most of the great apes participate willingly—not only because they know they will receive treats during the session, but also because they seem to enjoy interacting on the computer.

“We offer our apes free choice of participating in the studies, and they often seek it out,” says Lisa Stevens. “They like getting attention, and they like the challenge.”

Subiaul’s study challenges the animals with three different imitation tasks, all testing how the apes remember or choose images on the computer touch screen. In one task, Bonnie would see several pictures on the screen. Subiaul would then touch a series of pictures in a certain order—such as apple, then boy, then cat—on his screen. Bonnie would see this sequence flash in order on her screen. Then all of the pictures would scramble and reappear on the screen in a different configuration. Bonnie would then have to copy Subiaul, touching apple, boy, cat. “We’ve found that human children as young as two and a half can do this,” says Subiaul. “This skill shows an ability to learn a simple code from someone else. It’s an example of cognitive imitation. This is a basic learning skill. After all, how would we be able to learn from others if we couldn’t remember the order in which things happened?”

A second variation on this test adds a little more: The same thing occurs, but this time the researcher taps certain pictures to form a pattern; for example, apple, boy, boy, cat. The ape must remember the order of the pictures, but also the pattern of repetition. To receive a reward, Bonnie would have to tap apple, boy, boy, cat, as well. This tests the great apes’ understanding and appreciation of subtle motor skills: Do they notice the double tap? Are they paying attention to that level of detail? Do they recognize that they need to imitate the double tap to be rewarded with cereal or fruit?

Western lowland gorilla
The Zoo’s western lowland gorillas, like Kwame, use spatial learning and memory in everyday tasks. (Ann Batdorf /NZP)

The third test requires spatial memory, and is perhaps the most difficult one for the apes. Instead of memorizing the pictures themselves, the animal must recall the locations on the screen that the researcher touched. Subiaul might point at a sequence of pictures—first in the upper left of the screen, then bottom middle, then bottom right—much like punching in a PIN on a number keypad. Once the images are scrambled, the ape has to touch the same spots on the screen in order, regardless of what pictures show up in those spots.

Subiaul guesses that this will be the most difficult task for the apes to imitate, because it requires them to think more abstractly about space and action. The pattern is based on location, not concrete images. “My hypothesis is that humans are different from apes in that we have evolved specialized ways to create unique solutions to challenges. We can encode, imitate, and replicate actions,” he says. “Other primates appear to acquire some things by observation or cognitive imitation, but the rest they probably learn by trial and error.” Why have humans evolved the mental power to solve problems? Because, Subiaul explains, we’re pretty wimpy otherwise. Relative to other animals, our teeth and muscles are weak, we have no protective fur to speak of, and we’re unimpressive runners, jumpers, and swimmers. Our complex brains make up for our physical deficiencies in the wild. We have skills like strong spatial memory to help us with basic survival tasks, like locating a good fruit tree, figuring out how to pick the fruit, and remembering how to find the tree again.

Inside the Research

Since Subiaul’s research is taking place right at the National Zoo, it’s only natural to invite Zoo visitors to witness the work in action. Subiaul and his research team will not only allow Think Tank visitors to watch the apes participating in the experiments, they will also offer people the chance to participate in the research themselves. Since Subiaul’s other work at GWU compiles similar cognitive data on human children, he plans to make it possible for Zoo visitors to sit down at a touchscreen themselves and see how they fare on the tests. Data gathered from Zoo visitors could factor into the study’s results.

“Ultimately, our visitors will have a unique experience, as both participants and as observers,” says Stevens.

Subiaul will also hold regular seminars at Think Tank, and he’ll provide opportunities for local high school students to assist him in his work. He’s passionate about sharing his interest in primate cognition.

“This is a big deal because the question of cultural learning has never been addressed or studied this way. But what’s even more important is that we can only try to address these questions as long as we have our primate relatives around to study. That’s why we need to care what happens to them in their natural environment. We need to care about preserving biological diversity. If we lose our close relatives in the animal world, we lose the ability to better understand ourselves forever.”

Apes and Grapes

Another primate study at the National Zoo might help scientists understand humans better. In research conducted by animal psychologist Chikako King, the apes are put to the test by pointing at colored cups instead of computer touch screens.

King’s research centers on “metacognition.” King describes this tricky concept as “thinking about thinking”—in other words, having a sense of what’s contained in your own brain. She gives an example: If you’re a student with a big exam the next day, and you’ve studied thoroughly, you go into the test confidently. This is because you are consciously aware that you remember the facts you’ve studied. But if you didn’t study at all for the test, you would be fully aware of being ill-prepared—in this case, you know what you don’t know.

We experience situations every day where our mind must navigate this middle ground of cognition. The questions King asks are: Can orangutans and gorillas monitor their own memory? Do they remember that they remember something? How aware are they of their own mental process?

To answer these questions, King performs a series of tests involving cups and grapes. The ape sits on one side of an acrylic glass panel, while King sets up the parts of the experiment on the other side. She places grapes under some of three cups, then offers them to the participant. The ape can point through one of three holes along the bottom of the acrylic glass panel, indicating which cup it chooses. King lifts the cup to reveal whether there are zero, one, or two grapes underneath. The ape gets the grapes as its reward. When a test is in progress, it looks much like a magic trick.

Studying how apes make choices
Researcher Chikako King tests how conscious apes are of their own decisions. (Jessie Cohen/NZP)

One test involves King holding up two grapes and showing them to the ape before placing them under one of two blue cups. Then she holds up one grape and places it under a yellow cup. Having seen her do this, the ape tends to choose the blue cup for a two-grape reward.

“I always use red table grapes, which are one of their favorite treats. There should be an incentive to choose two grapes over one,” explains King. She notes that the orangutans carry this out more consistently due to previous research experience, whereas she had to spend time at the Zoo’s Great Ape House this fall training some of the gorillas to purposefully point at the cup with two grapes.

Another test adds a twist: Instead of showing the apes where the two grapes are hidden, King blocks the ape’s view with a box when she is hiding the grapes. She then lifts the box to reveal two blue cups, and places one grape under the yellow cup in full view of the ape. One blue cup hides two grapes and one has none. The yellow cup hides one grape, and this never changes. Does the animal gamble on choosing one of the blue cups, not knowing if it will find two grapes or none? Or does it pick the “safe choice”—the yellow cup with the one guaranteed grape?

“What I found is that they are more likely to choose the safe choice when they can’t see where I hid the two grapes,” says King. This indicates that apes use metacognition in gauging what they know they remember. Their decision seems to be based on self-awareness; they recognize their own uncertainty. However, some apes may just be more inclined to gamble. Others like to play it safe. “They’re just like people—they have individual personalities,” says King.

King gets to know the individual apes over time, since her study requires different versions of experiments in order to gather enough meaningful data. She is always the one to test the animals, in order to maintain consistent conditions. “They have to get used to you,” she says. “You just have to spend time with them, feeding them and being around.”

Visitors to the Zoo may not catch this sort of action, but they can see King demonstrate her metacognition study at Think Tank and the Great Ape House. She hopes that onlookers will understand that they’re watching more than just a fun find-the grapes guessing game. “This area of study is very new and exciting,” she says. “The reason why this is so important is that metacognitive skills are related to self-awareness. What we are really asking is, ‘What makes up consciousness?’ It’s important to let the public see that animals like orangutans and gorillas are very intelligent, and that they seem to have sophisticated cognitive abilities that are comparable to consciousness and self-awareness. We hope that people who recognize this will be more concerned about these animals’ welfare, both in captivity and in the wild.”

More: "Brainy Bonnie"