Question: why do we have a blind spot in between our eyes?

Reka Nagy answered on 14 Nov 2016:

To answer that, I’ll need to explain a bit about how our eyes work. The images that we see are projected onto the back of the eye, called the retina. The retina consists of a lot of light receptor cells that encode what we see into a nerve signal, which travels to the brain where it gets decoded into what we see.

The only issue is, these nerves need to travel from the retina to the brain somehow, so they need to exit the eye – and where this happens means that there can’t be any light receptors there, so the part of an image that falls in this area will not be sent to the brain. This is our blind spot.

Our brains are generally good at figuring out what should be here, by estimating based on the surroundings, which is why we don’t perceive a black spot when we see things. Sometimes, however, our brains can be fooled, which is how some optical illusions happen.