Take a piece of paper, and draw a cross and a dot about three inches to the right of the cross, like this
Close your left eye and focus on the cross. Move the piece of paper backwards and forwards, somewhere about 9 inches from your face, the dot will disappear. That's your blind spot! Although the dot is still right in front of you, it is now falling on the back of your eye where you have no photoreceptors, so it becomes invisible.
Notice that if you move your eye you can look at the dot. It is only when you focus on the cross that it is invisible. You can move the piece of paper side to side and the dot will stay invisible, because your eye will tend to stay focussed on the cross
+1 point: catch the mind filling in
Once you've found the blindspot,
