Another popular one – and quite unnerving if you’ve never seen it before! Here’s what I want you to do: close your left eye and just focus your right eye on the tiny static circle on the left of the screen. At some point the big circle will disappear as it crosses your ‘blind spot‘. If you can’t see this effect, it means you’re sitting too close/far from your monitor. Try sitting closer/further to the screen and repeat the test. So, have you managed to find your blind spot?