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Primate memory showdown

Are chimpanzees or people better at remembering numbers? Read on to find out.

In a memory-based competition between you and a chimp, who do you think would win? If you put yourself on top, you might want to guess again.

In a task that challenged test takers to remember numbers, a young chimp performed better than Japanese college students.

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A chimp has learned the order of the numerals 1 through 9 and wowed researchers with his ability to remember the location of those numbers on a screen after just a quick glimpse at them. To see a video clip of the chimp in action, click here or on the image above.

Image: AP/Wide World; Video courtesy of Current Biology

Here's how the test worked: At Kyoto University in Japan, human students and chimpanzee participants sat in front of a computer. Various combinations of five numbers, all ranging from 1 through 9, popped up at random places on the screen.

The numbers stayed on the screen for just a fraction of a second. In the first test, for example, participants saw the digits for 650 milliseconds. (That's about two-thirds of a second).

Then, each digit was replaced by a white square. Participants had to touch the squares in numerical order, based on the numbers that had been there a moment before.

In this test, the students put the boxes in the correct order about 80 percent of the time. A young chimp named Ayumu performed about as well.

During a harder trial, test takers were able to see the numbers for only 210 milliseconds.

After those flashes, students ordered the boxes correctly only about 40 percent of the time. But Ayumu still managed to select the boxes in the right order nearly 80 percent of the time.

Some people have what's called a "photographic memory," which allows them to remember a surprising number of details after just a quick glimpse at something. Ayumu's memory might work in a similar way, says lead researcher Tetsuro Matsuzawa.

The chimp's young age might have something to do with his impressive performance, too. In previous tests, the Japanese researchers found that young chimps tended to perform better than their mothers did.

The scientists are interested to see whether Ayumu loses his abilities as he gets older. They already know that young children sometimes have sharp memories that work photographically, but they typically lose this skill over time.

The new findings suggest more about memory than about math skills, researchers say. In fact, knowing too much about numbers may make memory tasks harder for people than for chimps.

"Chimpanzees may have a perceptual advantage that is slowed down in humans, whose knowledge of counting may interfere," says Sally Boysen of Ohio State University in Columbus.

What's more, Ayumu's performance doesn't mean that all chimpanzees have better memories than all people. Ayumu might just be an exceptional animal. And some exceptional people—including kids—might be able to outperform him.

In fact, overall, chimps and people had similar scores in the series of memory tests.

"I would argue that this is showing a major qualitative similarity" between species, says Elizabeth Brannon of Duke University in Durham, N.C., "rather than a major difference."

Going Deeper:

Milius, Susan. 2007. Chimp champ: Ape aces memory test, outscores people.Science News 172(Dec. 8):355-356. Available at http://www.sciencenews.org/articles/20071208/fob2.asp .

To see a video clip of Ayumu demonstrating his memory skills, click here (Video courtesy of Current Biology).

Sohn, Emily. 2003. It's a math world for animals.Science News for Kids (Oct. 8). Available at http://www.sciencenewsforkids.org/articles/20031008/Feature1.asp .

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