The surface of our retina is filled with light sensitive cells except for one spot, where it connects to the optic nerve – the blind spot.
To recognize your blind spot, cover your left eye with your hand, stand about a foot away from this screen and look at the circle on the left. Do you see the plus symbol on the right completely disappear? Moving forward or backward makes it reappear.
What’s more? The plus disappears without a trace. It doesn’t leave a gaping hole in our vision. Instead, our brain masks the blind spot by filling it in with the background that surrounds it.
And this isn’t the only trick our brains pull on us. One of the symptoms of sleep-deprivation is the inability to know that one is sleep-deprived.
We are all terrible at estimating how long something would take. We are also terrible at recognizing that we have this problem.
Our incompetence in doing a particular task gives us the illusion that we are more competent than we actually are.
Our senses are error-prone, but they are also good at keeping this fact a secret.