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> The human visual system adapts to the level of illumination it is looking at Anecdotally false. On really bright summer days (and on sunny days in the winter
by jarek 16y ago
> The human visual system adapts to the level of illumination it is looking at
Anecdotally false. On really bright summer days (and on sunny days in the winter with a lot of snow), outdoors are too bright for my visual system. I have to squint or my eyes will hurt, no matter how long I stay outside to adapt.
Anecdotally this is true for at least some of the people I know as well.
- CamperBob 16y agoYou're using them wrong. Just get a case^Wpair of $30 sunglasses.
- kristiandupont 16y agoDefinitely not false: http://en.wikipedia.org/wiki/Pupillary_light_reflex http://en.wikipedia.org/wiki/Pupillary_light_reflex The fact that bright light can still annoy you just shows that there is an upper limit (and there is a lower one too, obviously) -- not that it doesn't work.
- jarek 16y agoI should have quoted more of the parent's post: > ... so the times when eyes “hurt” are basically only when going from being dark-adapted to suddenly looking at something bright (emphasis added) Obviously I realize that pupils adapt, but I read the post to imply that there is no such thing as absolutely too bright.
- jacobolus 16y agoYou’re absolutely right. I didn’t intend to imply that excessively bright stimuli (such as when the ground is snow or concrete or sand and the sun is directly overhead), couldn’t be too bright even when adapted as far as possible. What I meant (and should have stated more precisely/clearly, not using the word “only”) was rather that, at the intensity of an iPad screen, adaptation should make any hurting stop. The iPad screen is several orders of magnitude dimmer than the brightest sunny days. Light adaptation takes us pretty darn far.