A picture of a banana flashes on a television monitor. A researcher holds a real piece of banana in front of Indah the orangutan.
Indah slowly lifts a long, bony finger and touches the symbol for "banana" on a computer screen, then moves her hand down the screen to hit the "send" symbol.
"Good girl!" says Rob Shumaker, the primate researcher, as he deposits the sliver of banana in her open mouth. Indah responds with an affectionate pat on her teacher's back.
If you suspect not much thinking is going on inside the beltway these days, consider the newest permanent exhibit at the National Zoo in Washington. It's called the Think Tank, and the main attraction is the Orangutan Language Project - the first effort to teach orangs how to communicate on a computer, all conducted in full view of the public. (For the moment, though, the zoo's gates are closed as part of the partial federal shutdown.)
At the rate they're going, Indah and her very big brother, Azy, should be surfing the Internet in no time. Still, Azy seems to like the old style of communication as much as the new: At the sight of a Georgetown University linguistics class visiting this day, he lets off a voluminous bellow, followed by several grunts.
The Think Tank itself, which opened in October, is a unique venture. "To my knowledge, there is no zoo or museum exhibit on animal thinking anywhere," says Benjamin Beck, the project leader and an authority on animal tool use. But at universities, he adds, "it's a very vital field of research."
The zoo's primate language program, which involves six orangutans, has been going for more than a year. Even though the zoo is closed, Indah and her classmates are apparently essential government workers and still doing their daily language drills.
Questions about all animals' thought processes hit the moment one enters the Think Tank: When a cat comes running at the sound of food pouring into a bowl, is he thinking or is that just a conditioned response? Is a beaver, building a dam, thinking? What about people who strap parachutes to their backs and jump out of airplanes?
It's an exhibit that, well, makes you think.
First, the ground rules. Most scientists define thinking as a three-step process: forming a mental image of something that isn't present, such as food; displaying the intention to get it; and then having the flexibility to find another way to reach the goal if the first idea doesn't work.
"The leap from intention to flexibility is the key to thinking," says Lisa Stevens, curator of the Think Tank. "So a salmon that swims upstream to spawn, but gives up when it reaches a dam, isn't thinking."
OVER the centuries, philosophers have debated whether non-human animals could think. Rene Descartes, who wrote in the 17th century, "I think, therefore I am," was referring only to humans. But four centuries earlier, Thomas Aquinas wrote that the gap in intelligence between humans and other animals was not so great.
"Thinking is something we've been wrestling with for at least 2,000 years," says Dr. Beck, the project leader. "We can't see it, we can't measure it, we can't weigh it, but we're all convinced there's something going on like thinking. It's still too early, I think, to be able to provide answers."
Clearly, though, Beck and company hew more toward Aquinas than Descartes. And in their study of primates - which carries Darwinian implications - they know they could be treading on touchy turf. Before the exhibit opened, in fact, Beck showed the texts for the graphics to creationists to look for any needlessly offensive words or phrases. He says they caught a few.
Now, a stop sign greets visitors at the door warning they may see some things inside they disagree with or even find troubling. So far, the zoo has heard no complaints. But the intent of the researchers is clear: "The more we understand about the great apes," says Mr. Shumaker, the primate specialist, "the better we understand ourselves."
Another aim, he adds, is to show kids that science is a "cool career, that scientists aren't just a bunch of geeks in lab coats."
Aside from language, the exhibit looks into two other domains for evidence of thinking: tool use and social behavior. Even the concept of a "tool" is under debate among experts. For example, is a spider's web a tool? Beck says yes, while others say no.
Beck also believes a hermit crab's shell is a tool, used as protection against weather and predators. Hermit crabs use shells abandoned by other crustaceans - clearly demonstrating imagery and intention in finding them. But do they demonstrate flexibility in the face of an obstacle? Probably not, he says. Therefore, they're probably not thinking.
But there's room for research. The zoo is advertising fellowships in animal cognition, and the Think Tank's hermit-crab exhibit is one possible focus.
The Think Tank also features a community of Sulawesi macaques, monkeys who live in complex social structures.
Researcher Jessica Hadley is looking into whether a macaque with a lower social status is likely to exhibit more innovative behaviors in trying new foods (out of necessity) than higher-status macaques.
Across the room, another colony - this one, of leaf-cutter ants - displays a complex society in action. But these ants aren't thinking, says Beck, a biopsychologist. Their behavior is genetically programmed.
"Our audience-testing showed people thought all animals were thinking all the time," says Shumaker, a graduate student at George Mason University in Washington. "Our biggest task is to make people understand that you can't assume that."
So, you mean, my two cats, who run to the edge of the sidewalk when they hear my car pulling up, aren't brilliant? Or Benjamin Beck's dog, who ran four blocks away from home to find some food she had discovered earlier on her walk, isn't smart as a whip?
The intellectual capability of house pets isn't really the focus of the Think Tank, which, as a part of the zoo, features wild animals.
But Beck says he'd like to have some demonstrations of specialized dogs when the weather warms up, such as dogs that do search and rescue and those used by law enforcement.
There's also potential to study the thinking of wild animals that live naturally on the zoo grounds, such as crows and squirrels.
And what about squirrels, anyway? Why do they demonstrate great ingenuity in breaking into bird-feeders but are always getting run over by cars?
Beck decided to find out. He went to a four-lane highway, got down on his hands and knees, and started to cross.
"I lived to tell about it, but I didn't cross the road," says the intrepid scientist, who, like many squirrels, turned tail part way and headed back.
"It was a very disorienting experience.... It helped me understand that it probably isn't the result of being stupid."
(Anyone who can't come see the Think Tank firsthand can visit via the World Wide Web, at http://www.si.edu/natzoo)