Is there some scientific explanation for the human eye locking onto a focal point involuntarily?

January 13, 2005 12:54 PM

Is there some scientific explanation for the human eye locking onto a focal point involuntarily? Example: Blankly staring out of a car window, my eyes always end up locking on to roadside trees or something and moving along with them. Or am I crazy?
posted by xmutex to Science & Nature (18 answers total)

Pattern recognition seems to be a good survival and reproductive tactic, seems to help with finding and focusing on food, healthy mates, predators, etc. The roadside trees are probably just decoration to your brain, as it subconsciously guides your car to an orgy/smorgasbord.
posted by AlexReynolds at 1:15 PM on January 13, 2005

Nope, me too.

I think most animals have a tendency to track objects in motion -- either as prey or predator.
posted by me3dia at 1:15 PM on January 13, 2005

The human eye does that naturally, and there's not a lot you can do about it.

...well, unless you have neurological damage. Then you might be able to stare straight ahead regardless of movement, but I don't think it's worth the tradeoff...

For example: stand up, and stare straight ahead. Try to focus on nothing in particular. Easy, right?

Now spin around in a circle. Your eyes will lock on repeatedly to things as they sweep past your field of view. It's hardwired into your optical systems. This used to drive me nuts (for some reason) as a kid -- I even tried to train myself to STOP focusing on things as they moved past & only stare straight ahead, but I just couldn't overcome the hardwiring. No, really. I spent hours trying.

god i was an unhappy kid
posted by aramaic at 1:19 PM on January 13, 2005

The weird thing to me is if you stare at a big tree or other lone object, as you drive past it, it appears to rotate in place.
posted by knave at 1:25 PM on January 13, 2005

Aramaic, you can do it if you blur your vision. Think ice skaters in a spin.
posted by Specklet at 1:30 PM on January 13, 2005

Don't ice skaters focus on the same point as they spin around? Ballerinas also. That's why they're always jerking their heads back to the same position. Keeps them from getting dizzy. I learned this from Billy Elliott, and the movies never lie.
posted by goatdog at 1:36 PM on January 13, 2005

Specklet: I can't, anyway. Believe me, I tried. Best I could ever manage was to look as far over into my peripheral vision as I could, and just keep my eyes there. Which is cheating.

Goatdog: I've always heard the same thing. Just watch; dancers are always snapping their heads around to the same place -- they're focusing on one object. My sister, anyway, was taught this back when she took ballet. But that was ages ago, so it might be invalid (although I doubt it).
posted by aramaic at 1:41 PM on January 13, 2005

What dancers and figure skaters and anyone who is spinning and needs to retain their balance do is called spotting (if I recall correctly). Try it yourself, it does actually work well. Pick an object and track it as much as you can before you have to snap your head around to see it again. Rinse and repeat.
posted by thebabelfish at 1:46 PM on January 13, 2005

I believe this is one reason it is so tough for a (seeing) actor to portray a blind person. The blind person can move his head with eyes open and pan perfectly smoothly without eyes focusing on one thing then the next then the next...
posted by Shane at 2:11 PM on January 13, 2005

Huge amounts of your cortical real estate are devoted to just this task. The large, rather diffuse areas that seem to be its final common pathway are called the parietal eye fields. Bilateral damage to the parietal eye fields is extremely uncommon; the area is well-supplied with blood and protected from trauma. But when such damage does occur, a bizarre syndrome named 'Balint syndrome' (after the describing neurologist) occurs; its main components are optic ataxia, ocular apraxia, and simultanagnosia (google for 'em!), which basically boils down to 'can't visually lock onto an object and smoothly pursue it.'

One of my professors used to do a neat little trick. He would hold a pen at arms length, off to the side; look at it with his eyes; and then smoothly sweep the pen across in front of him, tracking it with his eyes. The eyes follow the pursuit smoothly.

Then, he would explain that he was about to try his best to replicate the action - without the pen or the arm. His eyes would jerkily stutter across the room in a series of saccades, no matter how hard he tried to replicate the smooth sweeping motion.

Why? Because we're wired that way.
posted by ikkyu2 at 3:08 PM on January 13, 2005

I could have sworn I read somewhere that the figure skater head snapback was to force the balance-controlling fluids in your inner ear back into place and therefore prevent dizziness. Couldn't find anything to support that online though.
posted by hootch at 3:25 PM on January 13, 2005

Skaters blur their eyes and look at a "blurred median" in order to prevent their eyes from tracking, which is part of what causes dizziness.
posted by abcde at 3:41 PM on January 13, 2005

Well, that's kind of the opposite of what everyone else said actually, but I read it in Imponderables, so it has to be true :P
posted by abcde at 3:42 PM on January 13, 2005

Ballet dancers spot, where the head snaps back to the focal point. (I'm pretty sure that this does not have anything to do with inner ear fluids, it's just to keep from getting dizzy.) Ice skaters spin too fast to do this, so they unfocus their eyes and look at a "blurred median" in order to prevent their eyes from tracking. Like an imagined horizon line.

I think (although I haven't tried this, my coworkers would think it rather odd) that unless you are on ice, you won't be able to spin fast enough to get this blurred median. Perhaps this is why, aramaic, you couldn't do it...?
posted by Specklet at 4:48 PM on January 13, 2005

On a similar note, I had two problems when I was younger: as an adolescent, ant hills made me go into a blurred stare. Then, as a teen, parking lots gave me problems -- all those options! Now, much older, I don't have these problems.
posted by ValveAnnex at 7:09 PM on January 13, 2005

I can unfocus my eyes, if I just sort of sit around for a while. Then, of course, I notice that my eyes aren't focused on anything and ruin it immediately.
posted by Yelling At Nothing at 9:27 PM on January 13, 2005

I can confirm that ice skaters are trained not to spot. They do unfocus. It's not that difficult; it just takes some practice.
posted by litlnemo at 10:29 PM on January 13, 2005

I ride a motorbike, which may have a relation to this question....

"TARGET FIXATION

Have you ever wondered why the guy in front of you on the track goes straight on into the gravel instead of blasting around the bend… its because he is looking at the gravel… thinking Im not gona make it…. And hay presto he is up to his arse in kitty litter. He was fixated on going for a gravel bath and that’s what he did.

Ever fluffed a U turn… I have hit the kerb… why … because I was looking at it, instead of where I wanted the bike to go.

So target fixation is when you look at that tree, sheep, lamppost and end up hitting it. You see your brain steers the bike to where you are looking.. so if you go in too hot… for Gods sake take your eye off the side of the road and look for the way out of the bend…. If you don’t you will not make it. "

Have a guess why I know this is true.
posted by Frasermoo at 5:52 AM on January 14, 2005