It was really stupid - not quite Darwin Award stupid - but close. Now that my parents are gone I can write about it.
As a teen I became fascinated with the sensitivity of the human eye. It turns there are a lot of tricks you can use - I've written about playing with a few subtleties of your color vision to see colors in the night sky as well as my practice of night walking on dark nights without a light. Moonbows (like a rainbow, only from moonlight), very dim luminescent beetles, the phosphorescent decay of organic matter in still ponds and the reflection of light from the eyes of animals in starlight. There is a certain thrill in tapping your inner owl and walking around in near darkness. If you're a bit on the teenager side of the risk curve you can try running or cross country skiing without lights. And then the stupid thing I tried.
The night was exceptionally clear with only starlight. The hills were just black regions without stars. Night walking had opened up part of the outdoors I didn't know, but it made me wonder. Armed with a brand new driver's license and my Dad's old Ford Falcon, I had driven North of town past Benton Lake on Bootlegger Trail - far enough to be away from the light glow of town. I pulled over to the side of the road, taped over the instrument panel so none of the light came though and let my eyes adjust to the dark. I started the car without the lights and used averted vision to drive. It was easy to see where the road and even the center stripe was, but everything went away if you accidentally slipped and used the center of your eye. That's the hard part - you see a something and tend to focus on it. Suddenly your sensitivity drops off to less than a tenth of a percent of what it was and everything vanishes.
I probably drove that way for three or four minutes at up to thirty miles an hour. I did it again about a month later with a friend. He didn't have experience with averted vision so he didn't try, but I had a witness.
Don't ever try anything that stupid! But learning how to use your averted vision is a nice way to extend your view into the natural world. The world becomes a richer place when you learn how to see it a bit different. It is one of my forms of travel and particularly interesting when I'm visiting dark places for the first time.
You have three flavors of cones that are each sensitive to different "color" ranges. A total of about seven million and they're mostly in an area called the fovea near the center of your retina. There are also rods. One hundred and fifty million - approximately a boatload. They're generally more than a thousand times as sensitive than your cones and in some cases can be sensitive to individual photons. Learning how to use just the cones is the trick.
The fovea is small and densely packed giving you your detailed and color vision. It's what you usually think about when you consider vision. At it's center is a very small region about the size of a small dot of ink - about 0.3 millimeters or 300 microns. The thinnest blonde human hair is about 40 microns in diameter and the coarsest black hair about 120 microns, so its really small! It's all cones. If you plot the density of rods and cones on the retina going radially out from the center (the fovea centralis) you see the density of cones drop dramatically around twenty degrees out. The density of rods, on the other hand, is very low inside this area, and rapidly increases to a maximum around 20 to 25° out and then slowly drops off.1 Averted vision involves looking away from the center part of your vision. Ideally you want to be looking at least twenty five or so degrees out. Further out the density drops, but not that fast.. I aim for about 40° to prevent accidentally falling back into central vision. I can't do it without biting my lip - find your own technique:)
You can also use a camera to extend your range. Serious photography forces you to take careful note of what's in an image and you have any number of adjustments to play with. You can play with different wavelength ranges and see what is normally hidden to us. I like to play with different slices of time from tiny fractions of a second to minutes long.
We have fireflies around here in the Summer. Here's a simple 30 second time exposure. (f3.5, ASA 400 for what it's worth). Flashing signatures vary with species and I've found four in our area. It is relatively straight forward to analyze the signals and do serious observation. For something so beautiful it isn't deeply studied as one might think so you might discover new behavior!
Before stopping it seems reasonable to mention you can hack how your mind synthesizes and uses the vision it generations. Our brains turn out to be quite "plastic". Usage patterns can create new connections and destroy old ones. Playing a musical instrument develops certain regions in the brain as does speaking multiple languages fluently. Certain types of online interactions are currently under heavy study - it appears that multitasking leads to different neural optimizations along with easily finding answers without reflection. Jheri is mostly deaf - I've never met anyone as visually aware. She does an enormous amount of visual tracking and lip reads to the point where you don't realize she's hearing impaired.
Sports are another way to hack your sense of the world. People who are good at sports that require "field sense"- knowing the position and movement of others on the court and field- develop certain regions associated with orientation, but on a massive scale. They're doing it for multiple moving objects. I wonder if some people who are wonderfully athletic but aren't very good players in field and court sports have problems with this? (of course there are dozens of other areas that must work well too)
All of these changes seem quite normal to their owners - after all, we can't easily know what someone else experiences. A lot of questions arise. A few months ago a reader mentioned she was interested in how smell interacts with the body. It is certainly part of our interoception system and represents a nearly blue sky research area. There must be room for hacking. I've been talking to a neurologist and reading about dogs. But I'm out of time.
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1 the heights of the curves are different, but you get the idea - artistic license:-) This is from memory, but in the ballpark.
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