NASCAR: The necessity of top-notch vision.

So you’re driving down a racetrack at 200 mph. Things are flying past you at phenomenal speed, and you need to make sense of it all. Do you need spectacular vision? Sure. But it’s not just acuity (how good your vision where your visual focus is) that matters. What also matters is how well you can process things in the periphery. From an article about Nascar driver Tony Stewart in the New York Times:

For starters, Stewart has superb eyesight — 20/13 in one eye, 20/15 in the other — but it’s not visual acuity that matters so much as a driver’s ability to process everything that drifts into his periphery while he travels at 200 m.p.h. “A driver has to know what’s unfolding in front of him at a rate of a football field a second,” says Dr. Stephen Olvey, a founding fellow of the F.I.A. Institute for Motor Sport Safety.

When there is so much optic flow (a technical term meaning “stuff passing you as you are in motion”) is occurring, it makes sense that you have to be able to deal with something that suddenly appears in your peripheral vision, like another car, debris, or the wall. But not only do you have to detect that event, but you also have to react to it. You need to make a saccadic eye movement to bring the event from the periphery into the fovea - the small portion of central vision where acuity is the best.

A normal person can make a saccade within 250 ms (a rough estimate). That’s one-quarter of a second. 200 mph = 293 feet per second. Therefore, in the time it takes to make a single eye movement, you’ve traveled 73 feet at 200 mph. Add to that the fact that you’re effectively blind during a saccade, and suddenly 73 feet has passed before you know it.

Want to know how good your peripheral vision is? The New York Times article mentioned above has an excellent demonstration to see how good your peripheral vision is and how quickly you can move your eyes And if your performance is not as good as you’d like, you can train like a Nascar champ:

Greg Zipadelli, Stewart’s crew chief, says his driver hones his talent with a popular training tool: PlayStation.

Thanks to John Fedota for the link to the original New York Times article!