【英语时差8,16】眼见

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Don: Say you're looking at an object on a table in front of you. How long do you think your eyeballs stay in one position?

Ya?l: You mean, how long before they move? I'm going to guess... a minute.

D: More like less than a second.

Y: Yow!

D: Though we feel as if our eyes stay completely still when we focus on something, researchers have found they only stay still at most for a couple seconds--often just a few milliseconds. What's fascinating about this is that every time our eyes move, we are momentarily visually impaired¹. We aren't seeing anything but a blur². So if we're always moving our eyeballs, and are always impaired, why don't we experience the world as a confusing rush?

Y: I bet you have an answer.

D: Researchers at the University of Delaware have a good guess. They have done studies that show the brain is always extending the boundaries of what it sees-- adding in made-up information along the edges. This process is called "boundary extension," and it seems to be going on all the time. Say you're looking at a brick wall. You really only see a small section of it, but your visual processing system essentially³ says, "I can assume that beyond my visual field on either side are more red bricks, so for now I'll just add them in until I get better information." That process of constantly extrapolating on what you see may be what allows you to experience a calm and consistent visual world, even though the actual data coming in is much more fragmented.  

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