I knew a girl in high school whose eyes moved back and forth (over a very small angle) very rapidly. She would be there looking at you and talking to you and you could see her irises vibrating back and forth probably twice a second with movements of about 1mm.
She said the world looked fine to her (not moving).
What is this condition? Can it be fixed? What is going on?
As already mentioned, Nystagmus. If it is not a temporary drug/alcohol-induced or motion-induced nystagmus then generally, no, it can’t be fixed. There are a few drugs that seem to lessen its effects (see KarlGauss’s linked wikipedia article).
As for whether she sees as well as people without nystagmus, she probably doesn’t, but she doesn’t know that. Most people with nystagmus have decreased visual acuity compared to people without nystagmus.
Don’t all humans do this, to scan the sharpest part of our visual field over the parts of a scene of interest to us? I’ve seen psychology experiments where tracking systems can reconstruct a rough outline of what a person is seeing just by watching where their eyes track.
I took the question to be in reference to people who can do this on command or without conscious effort. I knew a kid like this in middle school, and he swore that anyone could do it with practice. Like burping. If you witness the extremely rapid movement first-hand, you realize quickly that not everyone can do it. It’s kinda… unnerving.
And thank the dope for finally laying this to rest. This thought has popped into my head from time to time and I never thought to ask about it.
I can do that. Rapid (multiple times per second) movements by sort of tensing and relaxing my eye muscles. I can also do rapid circular motions as well. It was actually quite useful in grade school and junior high. Kept me out of a lot of fights. Guy gets in your face and your eyes go all buggy. Freaked them right out. I have met a few other people who could do it and one kid learned to do it after he saw me do it. I can’t do it for long, maybe 30 seconds max. The world goes all squiggly when I do it.
Yes, laboratory studies do show that everyone makes continual small (and not so small) rapid eye movements. But continual eye movements that are obvious without special equipment as described in the OP (and are regular and odd looking, rather than being, say, someone darting their eyes about nervously), are the (mildly) pathological condition of nystagmus, as the first two responders said.
Eye movements are necessary for normal vision, but nystagmus movements will interfere with the normal eye movements, and mess you up. It is a bit like the difference between filming with a hand-held movie camera, pointing at different places as the action demands (although your eyes do it much faster and more frequently than would be acceptable for cinematography), and trying to do the same while you have the DTs.
Skyscrapers Are Gravestones is also correct that some people can produce a similar effect voluntarily: about 8% of the population according to one study, which also found some evidence that the ability is hereditary. I guess it is one of those useless talents like being able to waggle your ears.
I have this trait too, voluntary nystagmus — but no, it’s never been useful for squat, in my experience.
So if I can do both plus wag my tail . . . :dubious:
I do it semi-voluntarily when I’m really, really tired and trying to keep my eyes open. But my brain doesn’t filter out the movement so if I’m already feeling a little nauseous, it doesn’t help.
Yep, count me in, too, but I can’t do it for anywhere near 30 seconds. I also can’t see when I’m doing it; everything’s really blurry.
I think it is not so much that your brain does not filter it out, but that your brain is not in proper control of it. As Chronos mentioned, everyone’s eyes are in constant (and irregular) motion anyway, but that is under the brain’s control. It is a feature, indeed, a necessary feature of vision, not a bug. (If your eyes are held artificially still, relative to the visual environment - something that requires some quite fancy apparatus to achieve - in less than a second you will find yourself completely blind.) Normally, your brain is moving your eyes about in order to pick up the information it needs, and, for the most part, it is able to anticipate most of the information it will get with each movement. With nystagmus the brain has lost its normal fine control of the movements, and can’t fully cope with the unanticipated and unwanted changes in input that are being superimposed upon those produced by the normal “controlled” movements.
I can do the eye-shaking myself and have always enjoyed freaking out friends and others. My vision shakes as my eyes do their thing (as long as I want, over a minute easily and eventually the muscles tire/get sore) and I can’t move around or do anything while I am ‘shaking’. I have never seen myself doing it (per video, etc) but am told my eyes go pretty much side-to-side really fast and that is kinda what I ‘see’ but much, much too fast for any clarity. I learned about being able to do it early in life (kindergarten?) and was never shy about showing others, to say the least.
Its a GREAT party trick, especially when no one else was already aware of my ability (or its normalness as an anomaly). I have been able, in the past, to make persons definitely question their sobriety if I shook eyes, then denied doing so. Do it enough and other person starts thinking its their eyes - seriously. A real neat head-game sometimes 