Experts noted that the ordinary act of blinking takes up a surprising amount of waking time, on average in humans, spending between three and eight percent of their waking time with their eyelids closed.

Since blinks prevent an image of the external scene from forming on the retina, it is a quirk of evolution that we spend so much time in this seemingly vulnerable state, especially considering that blinks occur more frequently than is necessary just to maintain our well lubricated eyes.

“By modulating visual input to the retina, blinks effectively reformat visual information, producing luminance signals that differ dramatically from those we normally experience when looking at a point in the scene,” explained Michele Rucci, professor in the Department of Cognitive Brain and Science.

Rucci and her colleagues tracked the eye movements of human observers and combined this data with computer models and spectral analysis (analyzing the various frequencies of visual stimuli) to study how blinking affects what the eyes see compared to when the eyelids are closed.

The researchers measured how sensitive humans are to perceiving different types of stimuli, such as patterns at different levels of detail.

They found that when people blink, they are better at noticing large, gradually changing patterns —that is, blinking provides information to the brain about the big picture of a visual scene.

The results show that when we blink, rapid movement of the eyelid alters light patterns that are effective in stimulating the retina.

This creates a different type of visual signal for our brain compared to when our eyes are open and focused on a specific point, the experts stressed.

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