Dogs live through their olfactory sense much more than their visual one," Dr. Uri Burstyn, a veterinarian from Vancouver who also educates pet owners on YouTube, tells Mental Floss. Be sure to keep your hands curled, as if you were chopping vegetables, just in case the dog feels threatened and lunges to bite your fingers. If the dog seems pretty comfortable and doesn't recoil from your hand, the best place to pet a dog is under the chin. The one thing you should never do is immediately start patting the dog's head. This can be seen as a dominant, aggressive gesture because dogs generally keep their nose to the ground. If a dog feels something touching the top of his head, he might think it's a bigger dog attacking him and react in a defensive manner. "There's an old joke that dogs can't look up," Dr. Burstyn says. "They can, but hardly ever do."