The world looks different when your pupils are dilated.
Whenever we camp at a state park or any place that has big, well-lit public bathrooms, the kids and I do the night vision experiment. The experiment is pretty simple. You let your eyes get adjusted to the dark while sitting near a smoky campfire or talking a walk in the dark. Then when it’s time to go into the brightly lit bathroom before going to sleep at night, you keep your right eye closed and your left eye open.
For little kids, this means stumbling around with one hand over the eye while your parent tries to get you to brush your teeth or wash your face or use the toilet. Many of my friends have cursed me for teaching their kids to do this experiment. I think it's funny to watch all these kids in their pajamas, clutching toothbrushes and teddy bears, determinedly keeping one hand over their right eye. And it's worth the effort. Because then, when you leave the bright lights of the bathroom and walk back into the dark woods, you will have one eye with a fully dilated pupil and one eye with a pupil that is tiny. It's fun to stare into each other's eyes and see how bizarre this looks.
Of course, the real point of the experiment -- and you have to do this fast because your eyes will start adjusting again -- is to look at the dark world with first one eye, and then the other. Look out of your left eye, and the woods will seem dark, scary, impenetrable. Then close the left and look from the right eye, the one with the fully dilated pupil, and suddenly, the world is lighter. The dark masses look like distinct trees. The paths are clear.
Sometimes when I am having a hard time seeing something -- grasping, for instance, another person's perspective when it is completely different from mine – I remind myself about the night vision experiment, and how completely different the world can look when my pupil is dilated. I remind myself to be patient. I know from experience that sometimes I have to sit in the dark for 45 minutes before the full benefit of the night vision kicks in. And sometimes even then, I need to wait for moonlight.
Edited to add: If you are going to try this experiment with your kids, be sure to read the comments below.