The Blink of an Eye

April 24, 2017 | Posted in: Science

Le Monde Moderne: Mai, lithographic poster designed by Maurice Pillard Verneuil, printed in Paris by L'Imprimerie de Vaugirard, 1895.

Le Monde Moderne: Mai, lithographic poster designed by Maurice Pillard Verneuil, printed in Paris by L’Imprimerie de Vaugirard, 1895.

All day long we do it, and we almost never notice. Our eyelids shut for fractions of a second, and darkness should blip in our vision. But it doesn’t. We’re hardly ever aware of blinking, and this is one example of how the consistency of our vision (the seemingly continuous stream of imagery our eyes take in from the world around us) is really a myth our brains concoct. These tiny momentary dark spots are edited out so cleverly, we’re not even aware we’re missing anything.

Humans blink on average 15-20 times a minute. This is the spontaneous work of our body, like breathing or the beat of our heart, and our conscious attention isn’t needed. These fragmentary flashes of black add up to about 10% of our hours awake; that’s 10% of your day hidden from your eyes, and this missing vision is hidden from your awareness. Ah, our clever brain!

But why blink so much? Yes, blinking helps to clean and moisten our eyes, but the rate at which we blink is way beyond the necessary amount for such a simple explanation. And how does our brain edit out these moments of blackness from our awareness? The truth is, we’re still not clear on the whys or hows of blinking. Like any aspect of our bodies, what appears simple is in biological truth amazingly complex, and the more we learn the more questions we have.

From a set of original drawings by John Austen for a published volume of Shakespeare's Hamlet, 1922. Courtesy of the Folger Shakespeare Library.

Illustration from a set of drawings by John Austen for a published volume of Shakespeare’s Hamlet, 1922. Courtesy of the Folger Shakespeare Library.

Researchers have shown that blinking isn’t just random: viewers of a movie will blink in near unison at moments where the action lags; when listening to a friend we’ll blink during the natural pauses of their speech; and we all tend to blink at the end of sentences when reading. <——  you probably blinked there

A new study has shown this blinking business lights up areas of the brain associated with rest and a removal from the external world, like a split second mental break. Blinking could be a way of resetting ourselves, a moment of quiet before returning to the never-ending sensory stimulation of the world. But it isn’t easy for the brain to hide these breaks from our awareness, especially given that our eyes tend to move position during a blink and so must be quickly commanded back into proper alignment once our eyes reopen. Otherwise all this opening and closing of our eyelids would make our vision appear tremulous and confused. How exactly the brain manages to hide all these visual gaps from our awareness is still a mystery.

The Four Roses, Frant Dvořák, from Appleton's Magazine, Vol 2 (July-Dec. 1903).

The Four Roses, Frant Dvořák, from Appleton’s Magazine, Vol 2 (July-Dec. 1903).

We draw closed the blinds of our eyes, taking a moment from the endless external movie our retinas, optical nerves, and brain concoct together. Did you notice a blink at the end of that last sentence? Are you aware of it now? It’s not a habit I’d recommend developing, tends to make one look and feel quite crazy. It’s just another way our amazing bodies help us to navigate the thunderous sensory world we live in. Just remember, you never see it all…

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