• Question: if you have two eyes how come we only have one vision

    Asked by anon-186550 to Verity, Trystan, Raquel, Danny, Catherine, Andy on 13 Nov 2018.
    • Photo: Catherine Smith

      Catherine Smith answered on 13 Nov 2018:

      I don’t know a lot about neuroscience, but this is to do with your brain being able to combine the images from your two eyes into one. Having two eyes allows us to build up a 3D picture of the world as they look at the same point from two slightly different angles.

    • Photo: Verity Hill

      Verity Hill answered on 13 Nov 2018:

      Try closing one eye! The main thing that gets harder is that your “depth perception” is worse – it’s harder to work out how far away things are. This is because having two eyes helps us build up a 3D picture, as Catherine says.
      One thing we can say – it’s highly likely that two eyes are much better than one because all animals with eyes have at least two! This means that only having one eye must be a disadvantage.
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      (a side note: you can’t say this about all things that have evolved, but because eyes have evolved several different times over animal evolution, having two eyes is “convergent” meaning that different animals have come to the same solution for the same problem. This makes it more likely that it is actually an evolutionary strategy!)

    • Photo: Danny Ward

      Danny Ward answered on 13 Nov 2018:

      We do receives two separate images from both eyes…but our brain cleverly combines them together to make a single image that we see. This happens in the image processing part of the brain called the primary visual cortex in the occipital lobe (back of the brain).
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      Even more interesting is that our eyes actually see upside down! 👀 As light comes in to the eye, it bends so it sees things upside down. Our brain turns it up the right way before we realise though!

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