Brain Is Faster Than the Blink of an Eye
You blink about every 4-6 seconds, says David Burr in Current Biology,1 adding to over 17,000 blinks a day. Each time the world goes black for 100 to 150 milliseconds, as the eyelids attenuate the light a hundredfold. Why don’t we see the world like a flickering movie? We generally perceive an uninterrupted stream of visual information. It turns out that there is a synchronized interlock between the blink response and the visual cortex of the brain, such that the brain temporarily suppresses vision during each blink.
To find this out, a team of scientists in London, also publishing in Current Biology,2 repeated a 25-year-old ingenious experiment, but this time added functional MRI imaging on the brain. They made the retina see continuous light by shining it up the palate of test subjects wearing lightproof goggles, then watched how the brain reacted during blinks, even though the light seen by the retina (through the mouth) was continuous. Sure enough, the brain anticipated each blink by suppressing the visual cortex during the blink. This means that we don’t see the dark; when we blink, the brain just skips the interruption. See also the summary on EurekAlert.
1David Burr, “Vision: In the Blink of an Eye,” Current Biology, Vol 15, R554-R556, 26 July 2005.
2Bristow et al., “Blinking Suppresses the Neural Response to Unchanging Retinal Stimulation,” Current Biology, Vol 15, 1296-1300, 26 July 2005.
While this feat was evolving, we wonder if it was like the early fighter planes trying to shoot machine guns through the propeller. Until engineers figured out how to synchronize the firing between the propeller blades, how many test pilots shot themselves down? (Uh, whoops….) How many cheetahs in a full gallop had to learn to coordinate their attacks when the lights were on, till they got frustrated and sent their brains back to Tinker Bell’s workshop for an upgrade?