GREENVILLE, S.C. --
The experiment began with a racquetball that has now been replaced many times.
"Chaser! This is Blue," said John Pilley, a retired Wofford College psychology professor.
"Blue," Pilley repeated, and rolled the ball to his 2-month-old border collie.
He said the name again as Chaser took the ball in her mouth and held it just out of reach in a coy game of keep-away. Tail wagging, paws clattering, she chased Blue across the room in what became the first steps in her training to learn human language.
Blue led to Bamboozle, a stuffed orange horse, Choo Choo, a squeaky rubber train, Cinderella, Dora, Drumstick, Ears and Elmo. The filled up with toys -- 800 animals, 116 balls and 26 Frisbees -- kept in huge plastic bins on the back porch. Each had a different name written in marker; Pilley could no longer remember them all.
Chaser now world famous as the dog who knows more than 1,000 words, the largest known vocabulary of any animal except humans. Besides proper nouns, she knows verbs, adverbs and prepositions. She's learned that common nouns can identify different things. Ball could mean any round or bouncy object, Frisbee any spinning disk or ring. And she can make inferences. If asked to fetch a new toy with a word she's never heard, she'll pick the toy out from a pile of familiar ones.
As her language learning grew, so did the experiment. Pilley has recently started to teach Chaser commands with three elements of grammar, going from the basic "take ball" to "take ball to Frisbee." This is what excites Pilley most as a scientist -- that Chaser understands the concept that words play off of one another and that each word in a sentence can have a different meaning.
"We want to stretch it out so we have four, five elements of grammar. They've done that with dolphins and chimps, but no one's done it with dogs," he said.
Imitation, Pilley believes, requires imagination -- something inside Chaser's head is building a picture of what she has to do.
There seems to be no end to Chaser's abilities and her fame. Since Pilley's findings were first published in 2010, scientists have begun to follow his work as he explores the extent of what dogs are capable of. His approach has led to a new understanding of canine intelligence, one that makes us wonder just how sophisticated a dog's mind can be.