For instance, if you’re staring straight ahead and suddenly look at something to the left without moving your head, how fast is that eyeball rolling?
Typical saccades have a speed of 200-400 degrees per second.
For average 4cm diameter eyeballs that corresponds to a surface velocity of 7.0 - 13.96 cm/sec. The later figure is equal to 2.38 m/min or 0.14 km/h or 0.08 mph.
0.08 mph? I can’t believe that’s right. How can you possibly track a fast moving object? I understand the speed/distance correlation, that’s a given. Still, at 0.08 mph you couldn’t track an old lady with a with a walker and a leg iron if she was walking over your head.
0.08 mph sounds about right, but thats how fast the eyeball itself is moving. If you want to know how fast an object it can track, it depends on the distance. If the object is a fly flying 4 inches in front of your head then you won’t track anything faster than 0.2mph or so. If it’s a spacecraft flying across the Andromeda Galaxy, it can travel at Warp 13 and you’d still be able to track it. It has to be expressed by angular speed, as Squink did (i.e 200-400 degrees per second).
I agree with everything you said, but I get a different value. I get 0.8-1.6 MPH.
Oh, and don’t forget that you can move your head too. If something’s right in front of your face, I’ll bet that would give you a big speed boost!
Uh, that sounds more correct, thanks. :smack: I don’t suppose I could blame this on my unfamiliarity with non-metric units…
You can if you want. 
If you did it in your head, then no excuses are necessary. That’s as close as anyone can be expected to get.
I could probably get one going about 50mph. A good fast-ball pitcher like Nolan Ryan could, at his peak, get one going about 100mph.
Oh! You meant while still attached to the head? Nevermind.:eek:
14 cm/sec X 3600 sec/h = 50400 cm/h
50400 cm/h / 100,000 cm/km = 0.504 km/h
0.504 km/h X 0.6 miles/km = 0.3 mph
Sorry, I’ve no idea how I got to those other numbers.