Why Do People Blink Their Eyes?

    People blink(眨眼) their eyes tens of thousands of times every day. Scientists have long believed blinking was an involuntary movement and served mainly to keep the eyeballs wet. But a new study suggests it has a more important purpose.

    An international team of scientists from the University of California at Berkeley studied the blinking of human eyelids. The journal Current Biology published their findings. The team said they found that blinking “repositions our eyeballs so we can stay focused” on what we are seeing. They said that when we blink our eyelids, the eyes roll back into their sockets--the bony area that surrounds and protects the eyes. However, the researchers found the eyes don't always return to the same position. They said this causes the brain to tell the eye muscles to reorganize our eyesight.

    Gerrit Maus is the lead writer of the report. He serves as an assistant professor of psychology at Nanyang Technological University in Singapore. Maus says: “Our eye muscles are quite sluggish(迟缓的) and imprecise, so the brain needs to constantly adapt its motor signals to make sure our eyes are pointing where they're supposed to. Our findings suggested that the brain measures the difference in what we see before and after a blink, and commands the eye muscles to make the needed corrections.” The researchers said that without such corrections our surroundings would appear unclear and even jumpy. They said the movement acts “like a Steadicam(摄影稳定器) of the mind.”

    The researchers said they asked volunteers to sit in a dark room while staring at a small dot on a flat surface. They used special cameras to follow the volunteer's blinks and eye movements. After each blink, the dot was moved one centimeter to the right. The volunteers did not notice this, but the brain did. It followed the movement and directed the eye muscles to refocus on the dot. After the dot was moved in this way 30 times, the volunteers' eyes changed their focus to the place where they predicted it would be.

    Professor Maus says “Even though participants did not consciously register that the dot had moved, their brains did, and adjusted with the corrective eye movement. These findings add to our understanding of how the brain constantly adapts to changes, commanding our eye muscles to correct for errors in our bodies' own hardware.”