John W. Pilley conducted investigations involving his border collie named Chaser. Chaser had ~200 or so toys, each with a unique name; if Pilley asked her to fe

John W. Pilley conducted investigations involving his border collie named Chaser. Chaser had ~200 or so toys, each with a unique name; if Pilley asked her to fetch a toy by name, she would reliably find the corresponding toy out of a pile of all of them and bring it back. Pilley found that when Chaser was asked to fetch a toy whose name Chaser hadn't heard, Chaser would find the new toy she hadn't seen before in the pile and bring it back. He controlled for cues like face and body language by sitting still with his back to Chaser while giving the commands, so that he could neither see the toy being fetched nor unconsciously signal to Chaser. https://en.m.wikipedia.org/wiki/Chaser_(dog) https://en.m.wikipedia.org/wiki/Chaser_(dog)