ROCHESTER, N.Y. — We’ve all been there — having an intense conversation or focusing on an important task when our eyes suddenly feel dry and itchy. You blink hard a few times to re-wet your eyeballs and carry on. It’s such a dull and automatic behavior that few of us ever give it a second thought. However, a new study explains why we should care about blinking.
Researchers from the University of Rochester have found that the ordinary act of blinking is far more important than just keeping our eyes lubricated. Those split-second blackouts, when our eyelids completely close for a split-second, actually help our brains make sense of the visual world around us!
“By modulating the visual input to the retina, blinks effectively reformat visual information, yielding luminance signals that differ drastically from those normally experienced when we look at a point in the scene,” says Michele Rucci, a professor in the Department of Brain and Cognitive Sciences, in a media release.
It turns out that humans spend a surprising three to eight percent of their waking hours blinking. That’s a big chunk of time our eyes are essentially blind to what’s in front of us. So, why did humans evolve to blink so much?
In the study, published in the Proceedings of the National Academy of Sciences, Rucci and the team used sophisticated eye-tracking technology, combined with computer modeling, to precisely study how blinking impacts vision compared to when our eyes are open and fixated on something. They found that during a blink, the flashing motion of our eyelids rapidly changes the light patterns that reach our retinas.
This subtle “visual restart” helps reset our eyes to be able to detect bigger, more gradual shifts in our field of vision that would otherwise go unnoticed with a prolonged, steady gaze. Simply put, those oh-so-brief blinks clue our brains into the overall gist of a scene rather than the fine details.
“We show that human observers benefit from blink transients as predicted from the information conveyed by these transients,” says Bin Yang, a graduate student in Rucci’s lab and the first author of the paper. “Thus, contrary to common assumption, blinks improve—rather than disrupt—visual processing, amply compensating for the loss in stimulus exposure.”
The findings challenge the conventional wisdom that sight is a purely passive sense where our brains just interpret the visual data streaming in through our eyes. Instead, this research suggests vision is an active process involving the dynamic interaction of biochemical senses and physical movements — similar to other senses like smell or touch.
“Since spatial information is explicit in the image on the retina, visual perception was believed to differ,” Rucci concludes. “Our results suggest that this view is incomplete and that vision resembles other sensory modalities more than commonly assumed.”
So, the next time you blink and briefly lose sight of what’s in front of you, don’t worry about that microsecond of blindness. Instead, appreciate that it’s actually helping provide your brain with a high-level overview of the scene before your eyes reset to re-focus on the details.
