知识百科：为什么会产生错觉
明明在前进，却看到车轮在朝后转;画面上明明是一个三角形，从某个角度看过去却成了一条线。难道是眼睛出问题了?还是我们的错觉?Humans can see into the future, says a cognitive scientist. It's nothing
like the alleged predictive powers of Nostradamus(占卜者), but we do get a glimpse
of events one-tenth of a second before they occur.
And the mechanism behind that can also explain why we are tricked by
optical illusions.
Researcher Mark Changizi of Rensselaer Polytechnic Institute in New York
says it starts with a neural lag(神经滞后) that most everyone experiences while
awake. When light hits your retina(视网膜), about one-tenth of a second goes by
before the brain translates the signal into a visual perception of the
world.
Scientists already knew about the lag, yet they have debated over exactly
how we compensate, with one school of thought proposing our motor system somehow
modifies our movements to offset the delay.
Changizi now says it's our visual system that has evolved to compensate for
neural delays, generating images of what will occur one-tenth of a second into
the future. That foresight keeps our view of the world in the present. It gives
you enough heads up to catch a fly ball (instead of getting socked in the face)
and maneuver smoothly through a crowd. His research on this topic is detailed in
the May/June issue of the journal Cognitive Science,
That same seer(先知) ability can explain a range of optical illusions,
Changizi found.
"Illusions occur when our brains attempt to perceive the future, and those
perceptions don't match reality," Changizi said.
Here's how the foresight theory could explain the most common visual
illusions - geometric illusions that involve shapes: Something called the Hering
illusion, for instance, looks like bike spokes around a central point, with
vertical lines on either side of this central, so-called vanishing point(没影点).
The illusion tricks us into thinking we are moving forward, and thus, switches
on our future-seeing abilities. Since we aren't actually moving and the figure
is static, we misperceive the straight lines as curved ones.
"Evolution has seen to it that geometric drawings like this elicit in us
premonitions(预感) of the near future," Changizi said. "The converging lines
toward a vanishing point (the spokes) are cues that trick our brains into
thinking we are moving forward - as we would in the real world, where the door
frame (a pair of vertical lines) seems to bow out as we move through it - and we
try to perceive what that world will look like in the next instant."
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