Common Collie or Uberpooch?

"Fast mapping was thought to be something exclusively human. It is how children learn the meanings of new words," Fischer said. "Nobody thought this could be done by an animal."

She and her colleagues conducted a series of experiments on the 9-year-old border collie after his owners claimed he knew the names of about 200 objects -- his collection of toys, balls and stuffed animals.

In the first experiment, the researchers put 10 of Rico's toys in one room and Rico and his owner in another. The investigators then instructed the owner to order Rico to fetch two randomly selected items. As Rico ran into the other room and began searching for the items, he could not have picked up any hints from his owner because the owner was out of sight.

In 40 tests, Rico got it right 37 times, demonstrating he had a vocabulary comparable to dolphins, apes, sea lions and parrots that have undergone extensive training.

The researchers then repeated the test, except this time they put seven of his toys in the other room along with one he had never seen before. His owner then called out the unfamiliar name of the new toy. Rico correctly retrieved the new item in seven out of 10 tries.

"This tells us he can do simple logic," Fischer said in a telephone interview. "It's like he's saying to himself, 'I know the others have names, so this new word cannot refer to my familiar toys. It must refer to this new thing.' Or it goes the other way around, and he's thinking, 'I've never seen this one before, so this must be it.' He's actually thinking."

About a month later, the researchers tested Rico again, prompting him to retrieve objects from groups of four familiar and four new toys. He got it right three out of six times, a rate comparable to what a typical 3-year-old human toddler could do.

"Of course, for a child, a word very rapidly means much more than it does for a dog. They will quickly know it's a color word or an activity word. Their representation will be much richer than it is for a dog," Fischer said. "But in terms of this task, he is as smart as kids are."

Other scientists said important questions remain about whether animals are capable of complex syntax, which makes human communication unique. But many said Rico's apparent capabilities nevertheless appeared remarkable.

"A lot of people have argued that the perceptual and cognitive mechanism that underlie what we call language and speech acquisition are unique to humans," said Mark Bekoff, who studies dogs at the University of Colorado. "What this study shows clearly is that is not the case. What this shows is that other animals possess those cognitive and perceptual abilities."

Savage-Rumbaugh, who works with the bonobo Kanzi, said she has demonstrated, although not yet published, similar findings from tests on at least two other dogs.

"No doubt others will quickly replicate this study," Savage-Rumbaugh wrote in an e-mail, "and Rico will be shown to be an ordinary dog with a large vocabulary."