Why Don't We Notice We're Blinking?


Blinking happens often, but it usually goes unnoticed. moodboard/Thinkstock
Blinking happens often, but it usually goes unnoticed. moodboard/Thinkstock

We blink about 15 times each minute, sometimes in response to something, like going from a dark room into light. But most times, we blink for no reason at all — it's an involuntary response. So why don't we notice we've lost visual connection for a millisecond? That's what scientists wanted to discover.

For most people, eyesight is the dominant sense. In fact, about 30 percent of neurons in the cerebral cortex dictate vision, as compared to 8 percent for touch. But for a short time during every minute of your waking life, you're missing out on all that visual information when you blink. When you open your eyes after each blink, it's as if nothing changed. So why does the world appear so seamless even when your sight is disrupted every few seconds?

Researchers at the University of Illinois conducted three experiments, each involving 16 students with normal vision, to figure out why the world seems continuous across eye blinks. In each experiment, a blue letter "A" was projected on a screen, while an eyetracker recorded eye blinks (in this case, voluntary ones).

Participants had to determine how long the letter appeared on the screen in sessions when they blinked and in others when they didn't blink, as a control. Based on prior research, the scientists hypothesized that we either maintain memory of images while we blink, or else we backdate images to the beginning of a blink, filling in the missing information.

But because the study participants underestimated how long an image appeared when they blinked, the researchers concluded that neither hypothesis was true. Instead, they suggested that we ignore blinks, possibly because our brain sends a signal that it's just a blink, not some interruption from outside our bodies. This idea is backed up by an earlier study that showed how we don't notice blinks, but we do notice when lights flicker for the same amount of time.

So, maybe science hasn't got it all figured out yet. Until it does, though, try not to blink — you might miss something.