First things first: Chaser was a dog, but indeed a special one. She was owned by Dr. John W. Pilley, a psychology professor at Wofford College in Spartanburg, S.C. One of his favored fields of research was animal cognition, so perhaps it is not surprising he loved animals; Chaser was a gift from his wife, Sally, in 2004. Dr. Pilley had retired from Wofford in 1995, but was still active on campus. Yet with more time on his hands, he decided to make an experiment out of Chaser, a border collie: for three years, he spent several hours a day teaching the dog to understand words. Rather than reward the dog with treats, he consciously sought to make learning fun for Chaser, using toys. He’d present Chaser with a new toy — a frog, perhaps. He would show the toy to Chaser and repeat “frog” dozens of times, then hide it and ask Chaser to “find the frog.” Pilley did this again and again. Family members would also train Chaser using the same techniques.
Chaser learned a lot of words: the names of 800 cloth animal toys, 116 balls, 26 Frisbees, and dozens of other items — 1,022 total things. She was tested by being asked to retrieve specific items, which she accomplished with high accuracy, for instance finding the specific ball named. “She learned the theory of one to many and many to one,” says Pilley Bianchi, Dr. Pilley’s daughter, who was involved in training Chaser, “which is learning one object could have many names and many names can apply to one object or one person.” Dr. Pilley wrote it up for scientific journals, including Behavioural Processes and Learning and Motivation, documenting that Chaser had the largest tested memory of any non-human animal. Chaser became known as “the world’s smartest dog,” yet the Pilley family rejected that contention. “What we would really like people to understand about Chaser is that she is not unique,” Bianchi said. “It’s the way she was taught that is unique,” the techniques developed by her father. “Her language learning is very high-level, powerful science.” People were so intrigued by the whole concept that Dr. Pilley wrote a book about his work with the dog in 2013. Chaser: Unlocking the Genius of the Dog Who Knows a Thousand Words became a New York Times best-seller. “The big lesson is to recognize that dogs are smarter than we think,” Dr. Pilley said in 2014, “and given time, patience, and enough enjoyable reinforcement, we can teach them just about anything.” Dr. Pilley died in 2018 at 89. Chaser died July 23, at 15.