How smart is your dog?

UPDATE: "The Smartest Dog in the World" aired on Oct. 5, 2014. Anderson Cooper is the correspondent. Denise Schrier Cetta, producer.

Your dog is a lot smarter than you think, though he or she is probably not as smart as Chaser, who may be the smartest dog in the world. Scientists are just beginning to understand how smart dogs really are. Chaser has a vocabulary more than twice that of a two-year-old child. Anderson Cooper reports on Chaser and some of the fascinating things researchers are learning about man's best friend in a story to be broadcast on 60 Minutes, Sunday, Oct. 5 at 7:30 p.m. ET and 7 p.m. PT on the CBS Television Network.

John Pilley, a retired psychology professor, has worked with his border collie, Chaser, for several years and trained the dog to recognize the names of over a thousand toys. "My best metaphor is this is a two-year-old toddler," Pilley tells Cooper. "She's our child." The "child" is familiar enough with the names of 800 cloth toys, 116 different balls and over a hundred plastic toys to be able to pick the one named by Pilley out of a pile on the floor. Pilley demonstrates Chaser's skill with several different toys.

A two-year-old child generally knows about 300 words. Chaser is using the same skills a child would use to learn the names of her toys, say scientists

"This is very serious science," says Brian Hare, an evolutionary anthropologist at Duke University. "We're not talking about stupid pet tricks. Chaser is learning tons, literally, thousands of new things by using the same ability that kids use when they learn lots of words."

Researchers have begun to use MRIs and blood testing to learn more about dogs' feelings and intelligence. Hare says that when dogs look at their masters, scientists have detected oxytocin, which is also found in humans, that is known as "the love hormone," whose presence indicates warm or loving feelings. "What we know now is that when dogs are actually looking at you, they're essentially hugging you with their eyes," Hare tells Cooper.