"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.
...
Chaser understood that words have independent meaning and understood common nouns as well as proper nouns, Ms. Bianchi said.
If Chaser had 30 balls, Ms. Bianchi said, she would be able to understand each one by its proper-noun name and also as a part of a group of objects. “She learned the theory of one to many and many to one, which is learning one object could have many names and many names can apply to one object or one person,” she said."
https://www.nytimes.com/2019/07/27/science/chaser-border-collie-dies.html?module=inline
In 2013, Dr. Pilley published his findings that explained that Chaser was taught to understand sentences containing a prepositional object, verb and direct object.
...
Chaser understood that words have independent meaning and understood common nouns as well as proper nouns, Ms. Bianchi said.
If Chaser had 30 balls, Ms. Bianchi said, she would be able to understand each one by its proper-noun name and also as a part of a group of objects. “She learned the theory of one to many and many to one, which is learning one object could have many names and many names can apply to one object or one person,” she said."
https://www.nytimes.com/2019/07/27/science/chaser-border-collie-dies.html?module=inline