Many owners struggle to teach their dogs to sit, fetch or even bark on command, but John W. Pilley, a professor emeritus of psychology at Wofford College, taught his Border collie to understand more than 1,000 nouns, a feat that earned them both worldwide recognition.

For some time, Dr. Pilley had been conducting his own experiment teaching dogs the names of objects and was inspired by Border collie farmers to rethink his methods.

Dr. Pilley was given a black-and-white Border collie as a gift by his wife Sally.

For three years, Dr. Pilley trained the dog, named Chaser, four to five hours a day: He showed her an object, said its name up to 40 times, then hid it and asked her to find it. He used 800 cloth animal toys, 116 balls, 26 Frisbees and an assortment of plastic items to ultimately teach Chaser 1,022 nouns.

In 2013, Dr. Pilley published his findings that explained that Chaser was taught to understand sentences containing a prepositional object, verb and direct object.