Kaminski "et al. "eliminated the Clever Hans effect using a strict protocol: each of the 200 items whose names Rico knew was randomly assigned to one of 20 sets of 10 items. While the owner waited with the dog in a separate room, the experimenter arranged a set of items in the experimental room and then joined the owner and the dog. Next, the experimenter instructed the owner to request that the dog bring two randomly chosen items (one after the other) from the adjacent room.