Scientists at University College London have used photonic techniques to study what happens when humans blink. They wanted to know why shutting the eyelids hardly registers in visual perception. Even though people normally blink about 15 times a minute to moisten their eyes, they are not consciously aware of the world going dark.

Volunteers wore lightproof goggles in a functional MRI brain scanner as the scientists shone strong light on their eyeballs from inside the head via fiber optic cable inserted through the mouth. Because the light remained constant even when the volunteers blinked, the researchers could measure the effects of the eyelid movement on brain activity, not just as a response to light entering the eye.

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Volunteers’ eyes are illuminated via fiber optic cable during experiments on the blinking mechanism. Courtesy of University College London.

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They found that blinking suppresses brain activity in the visual cortex and the parietal and prefrontal regions for the duration of the blink. People don’t experience the brief blackouts because their minds actually miss them.

Could this perchance explain why persistent fluttering of the eyelashes makes one seem scatterbrained?