How can one eye alone provide depth perception? © Getty Images

How can one eye alone provide depth perception?

Time to don the eye patch, you will still be able to determine depth thanks to a few techniques the brain uses.

Asked by: Roger Britton, Lanner

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One of the main ways our brains perceive depth is by using a technique called ‘binocular disparity’, which compares the slight differences in view from each eye to determine the distance to objects.

If you close one eye, however, you’ll notice that you can still perceive depth. This is thanks to a number of extra visual cues that our brains exploit. For example, we know the size of things from memory, so if an object looks smaller than expected we know it’s further away.

Our brains also understand perspective, where parallel lines (such as train tracks) get closer together as they stretch into the distance. There’s also a nifty mechanism called motion parallax: when we’re moving, objects appear to shift by different amounts, depending on their distance from us.

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