Night vision is laterally independent
Couldn't get to sleep tonight, because I was too excited about going home for Christmas tomorrow. So I picked up the mobile phone (it was under my pillow, since I use it as an alarm clock), and read some news on WAP. After having read all my bookmarks, I put ut down.
When looking at the dimly lit room, I noticed that the image from my left eye looked darker than the one on the right. I had held the display of the phone up against the left eye when reading, since that is my dominant eye. So the left eye had got lots of the light, but the right eye next to nothing. Hence, the left eye was accommodated for day vision, while the right one was still in night vision mode.
It struck me that the first time someone discovered this, it must have been an important result in neurology. Consider this: in the pre-technological era when the human brain spent most of its time evolving, few light sources that would be seen only by one eye existed. Hence, there should be no evolutionary advantage of having a separate feedback mechanism for each eye, as opposed to a central "light meter" that responds to the overall brightness of the visual field. Therefore, the reason that the dilation of the pupil of the eye is controlled separately for each eye, must have something to do with some structure in the brain that was "already there", ie. evolved for a separate reason.
Trying to go back to sleep now -- have to be up in less than six hours.
(If you know something about this that I haven't mentioned, please feel free to drop me an e-mail.)
[Thursday, Dec 16, 2004 @ 02:15] | [science] | # | G
