This Dog’s Way With Words Turns Fetch Into Child’s Play

Dog owners have long suspected it and now German scientists have proved it -- dogs can have a large vocabulary and learn new words in a manner previously thought to be unique to humans.

They can’t speak, of course, but dogs can understand much more than previously believed, and can learn and retain new words with a facility nearly equal to that of a 3-year-old toddler, the researchers report in today’s edition of the journal Science.

Researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig studied a border collie named Rico that had a vocabulary of at least 200 words and was adept at using them. While Rico may be the Einstein of dogs, the researchers said, other dogs, and perhaps even other animals, may have a similar ability.

“We wonder what prevents animals from speaking. The limitations are not their capacity to hear or understand,” psychologist Julia Fischer told a news conference in Berlin.

Pet owners already know that dogs -- and other animals -- can respond correctly to spoken commands. Research also has shown that other animals, including apes, dolphins and parrots, can understand as many words as Rico does. But those animals typically learn words by repetition and reward.

The new findings suggest that some animals may possess a higher-level language ability that allows them to acquire and process words like humans, eroding the belief that humans are unique in language ability.

Rico appears to use a technique called “fast mapping,” which young children use to learn new words by matching them to new objects. Fast mapping had not previously been demonstrated in animals.

“Rico’s word-learning abilities surpass those of nonhuman primates such as chimpanzees, who have never demonstrated this sort of fast mapping,” said psychologist Paul Bloom of Yale University, who wrote a commentary about the study in the same issue of Science.

Nine-year-old Rico is owned by Witold Krzeslowski and Susanne Baus of Dortmund. Baus told the news conference that she began teaching Rico the names of objects, mostly toys, when he was 10 months old and was laid up for nearly a year after a shoulder operation.

“At the start, it was three to four objects, but it has risen to 200 or 250,” she told reporters. “I don’t know what the limit might be, but we’ve now run out of space.”

Some of the items have German names, such as Zitrone (lemon) and Kaninchen (bunny). Others have English names, such as Mr. Green, Seahorse and Big Mac, so Rico might be said to be bilingual.

Rico came to Fischer’s attention when he appeared on the European television show “Wetten Das?” (“You Want to Bet?”) and astounded the audience with his ability to fetch specific items. Fischer received permission to test Rico in the owners’ home.

Fischer designed the studies carefully to avoid the possibility that Rico was taking conscious or unconscious cues from his owner. That phenomenon is known as the Clever Hans effect, after an early-20th century horse who was thought to be performing mathematical calculations but was actually picking up subtle cues from his questioner.

In a typical test, the researchers would place 10 items in a room in the house while Rico and his owner waited in another room. Rico would then be told to fetch an item while the humans waited out of sight. Rico retrieved the correct item 37 out of 40 times.

He also responded correctly when told to put the item in a box or deliver it to a specific person, indicating that he understood that the words corresponded to specific objects.

Going one step further, the team then placed a new item that Rico had never seen in the room along with six of his toys and told him to fetch the new toy using a new name. Seven out of every 10 times, Rico returned with the correct object.

“This tells us that he can do simple logic,” Fischer said. Rico apparently concluded that the unknown name referred to the unknown object.

When tested again a month later with several of the previously unknown objects, Rico was correct half the time. “This retrieval rate is comparable to the performance of 3-year-old toddlers,” the researchers wrote.

“Such fast, one-trial learning in dogs is remarkable,” according to Katrina Kelnar, Science’s deputy editor for life sciences. “This ability suggests that the brain structures that support this kind of learning are not unique to humans.”

But Bloom cautioned that Rico’s understanding was still very limited. “Children can understand words used in a range of contexts,” he said. “Rico’s understanding is manifested in his fetching behavior.”

He conceded, however, that Rico’s feats were impressive.

“Perhaps Rico is doing precisely what a child does, just not as well,” he said. “A 2-year-old human knows more than a 9-year-old dog, after all, and has a better memory, and a better ability to understand the minds of adults. Rico’s limitations might reflect differences in degree, not in kind.”

Biologist Sue Savage-Rumbaugh of Georgia State University, who has taught a bonobo ape named Kanzi many symbols that it uses to communicate, said Thursday that she had obtained similar results with two dogs but had not published them.

She thinks that Kanzi, Rico and other animals probably understand words well enough that they could speak if they had the proper vocal apparatus. Rico might already be trying to speak, if only we could understand him, she said.

So dog lovers may have been right about the animals all along.

“Dog owners often boast about the communicative and social abilities of their pets,” Bloom said. “This study seems to vindicate them.”