You might not realize it (you will now that we brought it up), but you blink about 15 to 20 times every single minute. When you do so, you eye actually rolls back in its socket, and then returns to normal when you open your eye. So why don't we feel plunged into darkness and get disoriented 21,000 times (or more) a day? Researchers have puzzled it out.
In the study, a joint effort between Singaporean and American universities, 12 adults sat in a dark room staring at a dot on a screen which was moved one centimeter to the right after each blink. Their eye movements were tracked with infrared cameras. Study lead author Gerrit Maus jokingly called the research "the most boring experiment ever."
The participants didn't consciously notice the movement, but the cameras picked up on the fact that their brains did. After about 35 blinks, the eye was automatically steered by the brain's oculomotor mechanism to the spot where the dot was expected to be. In other words, the brain began to predict where the eye should be after the eyelid was lowered and then raised.
In addition to tracking dots on the screen, the researchers say that this ability of the brain to reposition our eyes after each and every blink helps us see the world clearly.
"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," Maus said.
Without the help of this guidance system, they say, our vision would show us a more shadowy and erratic picture of the world.
"We perceive coherence and not transient blindness because the brain connects the dots for us," said study co-author David Whitney, a psychology professor at UC Berkeley who participated in the study.
"Our brains do a lot of prediction to compensate for how we move around in the world," said co-author Patrick Cavanagh, a professor of psychological and brain sciences at Dartmouth College, who was likewise involved in the research. "It's like a steadicam of the mind."
The team's research has been published in the journal Current Biology.