30 January, 2017
People blink 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
An international team of scientists studied the blinking of human eyelids. The team reported to researchers from the University of California at Berkeley. The journal Current Biology published their findings.
The team said it found that blinking "repositions our eyeballs so we can stay focused" on what we are seeing. It 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 say this causes the brain to tell the eye muscles to "realign" our eyesight.
Gerrit Maus was 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 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 suggest that the brain gauges the difference in what we see before and after a blink, and commands the eye muscles to make the needed corrections."
The researchers say that without such corrections our surroundings would appear unclear and even jumpy. They say the movement acts "like a steadicam of the mind."
Researchers say 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 muscles to correct for errors in our bodies' own hardware."
I'm Christopher Jones-Cruise.
VOANews.com reported this story. Christopher Jones-Cruise adapted the report into Learning English. George Grow was the editor.
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Words in This Story
blink – n. to close and then open your eyes very quickly
focus – v. to look at something so that you can see it clearly
realign – v. to change the position or direction of (something) slightly usually in relation to something else
sluggish – adj. moving slowly or lazily
imprecise – adj. not clear or exact; not precise
gauge – v. to make a judgment about (something)
steadicam – n. a kind of video camera that is stabilized so it films images in the same way as the human eye works