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Sightless Light Detection

January 16, 2008

Even some blind people can respond to light in non-visual ways.


Detecting light without sight. I’m Bob Hirshon and this is Science Update.

Light not only lets us see: it also resets our body clock and makes us more alert. Now, researchers have shown that these responses are independent of vision. Harvard Medical School neuroscientist Steven Lockley and his colleagues studied two unusual blind patients: Their eyes lack the light receptor cells that we use to see, but still had intact retinal cells that control our non-visual responses to light, primarily blue light. Lockley says one patient felt more awake under blue light than green, and that’s not all.

STEVEN LOCKLEY (Harvard Medical School):
We made him react quicker under blue light compared to green, and we also showed that his brain was in a more activated state under blue light.

The other patient could even tell whether a blue light was on or off, even though she couldn’t see a thing. I’m Bob Hirshon, for AAAS, the science society.