So when you blink, you don't notice it getting dark, do you? New research at University College London has found out why - your visual cortex automatically shuts down every time you blink .
They got some volunteers to wear light-proof goggles and put a fibre optic cable in their mouth which shone light on to their retinas by making their whole head glow, while lying in an fMRI scanner. The fibre optic was to make sure that it was the blinking, rather than the lack of light, that made the brain do what it did. Whenever the volunteers blinked, brain activity in the visual cortex was suppressed.
So that's why you don't notice yourself blinking. Though I bet you're noticing it now you've read this eh?
1. Bristow D, Haynes JD, Sylvester R, Frith CD, Rees G: Blinking suppresses the neural response to unchanging retinal stimulation. Curr Biol. 2005 26;15(14):1296-300.