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When I try to rotate my eye, both of my eyes will rotate the same amount and in the same direction (obviously).

I'm wondering if it is possible to control each eye separately. I've never seen anyone that can do this (except some pics on the internet which I'm not sure if they are digital edits simply for fun).

Is it possible? If not, why? Is it because they are both controlled by the same nerve? Or is it simply because we are not used to it and it's super difficult (but possible)?

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    $\begingroup$ "I'm wondering if it is possible to control each eye separately" - have you ever tried focusing on the tip of your nose? Maybe not quite the same thing as e.g. controlling your arms separately, but you certainly can move your eyes in different directions. $\endgroup$ – user14666 Oct 3 '17 at 2:29
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Each eye is controlled separately. Three cranial nerves emerge at the brain for each eye to control the so called extraocular muscles. That we usually move both eyes in one direction is due to that our brain is trained that way. Nonetheless, we sometimes move each eye individually, for example when looking at an object that is very close to our face (convergence). I wonder that you have not noticed it on yourself, since it is a pretty common eye movement. Further, you can train your brain to perform other, rather unusual movements, as you can see in this video.

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  • $\begingroup$ Ops thanks for the tip! I forgot about convergence, since I was busy thinking about moving them both outside. $\endgroup$ – Jack Johansson Oct 2 '17 at 21:54
  • $\begingroup$ So it's like when you play Mario and you instinctively start pressing B when you press over. You don't think about it, you just do it! $\endgroup$ – corsiKa Oct 2 '17 at 23:00
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There are basically four different types of eye movements:

  1. smooth pursuit (think about following a moving target with both your eyes, note how smooth the movement is)

  2. saccades (think about moving your eyes without fixation on a specific target, note how jerky the movement is)

  3. vergence (the other answer mentioned "convergence", this is an example of a vergence movement)

  4. vestibulo-ocular movements (these are mainly reflex movements which depend on the "position-sensing" apparatus of the inner ear)

The motor control of the eyeballs (globes) is mediated in a fairly complex way via the third, fourth and sixth cranial nerves. The coordinated movement of the eyeballs is mediated neurologically in a really complex way involving multiple brain and brainstem centres (nuclei).

To explore this in detail, you really need a good textbook in neuroscience. For what it's worth, I've found a web reference that covers the gist: https://www.ncbi.nlm.nih.gov/books/NBK10991/

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