明明在前進，卻看到車輪在朝后轉；畫面上明明是一個三角形，從某個角度看過去卻成了一條線。難道是眼睛出問題了？還是我們的錯覺？

    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（神經滯后） that most everyone experiences while awake. When light hits your retina（視網膜）, 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（沒影點）. 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（預感） 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."