The dog laugh is a breathy exhalation that sounds like an excited burst of panting. We could call it social panting: it is a pant only heard when dogs are playing or trying to get someone to play with them. Dogs don’t seem to laugh to themselves, off sitting in the corner of the room, recollecting how that tawny dog in the park outsmarted her human this morning. Instead, dogs laugh when interacting socially. If you have played with your dog, you have probably heard it. In fact, doing your own social panting toward a dog is one of the most effective ways to elicit play.

Coming full circle, a wide-open mouth with teeth mostly covered—a yawn—is not a sign of boredom, as often assumed by analogy with our own yawning; instead, it may indicate anxiety, timidity, or stress, and is used by dogs to calm themselves or others.

On average, dogs’ wags tend more strongly to the right when they suddenly see their owners—or even anything else of some interest: another person, or a cat. When presented with an unfamiliar dog, dogs still wag—more that tentative wag than the happy wag—but tending to the left.

The lens of the eye, which adjusts its curvature to focus light onto the retina, doesn’t accommodate to nearby sources of light. In fact, dogs might overlook small things right in front of their nose (within ten to fifteen inches), because they have fewer retinal cells committed to receiving light from that part of the visual world. You need no longer puzzle at your dog’s inability to find the toy that he is nearly stepping on: he’s not got the vision to take note of it until he takes a step back.

The shorter the nose, the less visual streak; the longer the nose, the more visual streak. Dogs with the visual streaks have better panoramic, high-quality vision, and much more peripheral vision than humans. Dogs with the pronounced area centralis have better focus in front of their faces.

Similarly, fluorescent lights are so annoying because they operate too close to the human flicker-fusion rate. The electrical devices used to regulate the current in the light function right at sixty cycles per second, which those of us with slightly faster flicker-fusion rates can thus see as a flicker (and hear as a buzz). All indoor lights fluorescently flicker to houseflies, with extremely different eyes than ours.

One could say that dogs see the world faster than we do, but what they really do is see just a bit more world in every second. We marvel at dogs’ seemingly magical skill at catching a Frisbee on the fly, or following a rapidly bouncing ball. Their Frisbee-catching procedure, as has been documented with microvideo recording and trajectory analysis, turns out to match nicely the navigational strategy naturally used by baseball outfielders to line themselves up with the arc of an incoming ball. Excepting a few phenomenal outfielders, dogs actually see the Frisbee’s, or the ball’s, new location a fraction of a second before we do. Our eyes are internally blinking in those milliseconds that a flung Frisbee is moving along its course toward our heads.