The Momentum Blog
Posted May 2, 2012 by Nathan M Farrugia
Switch off the cones and start using those rods, baby
This might sound like the premise for a porno (bow chicka wow wow) but it’s really about how your eyes work in darkness. Your eyes use cones for color and fine detail. Rods on the other hand see only in black and white, but they’re a thousand times more sensitive to light. Oh, and there’s about as many of them as there are Twilight fans. About 120 million of them. And at night, much like Twilight fans, they can’t see color or detail or see what’s right in front of their faces. And I’ll explain why.
Rods take a lot longer to adapt than cones, so your night vision is not instant. It will take your eyes 45 minutes to gain complete night vision, which coincidentally is about as long as it takes for Viagra to kick in.
The worst time for night vision, unlike Viagra, is dawn or dusk. It’s this transitory period where your eyes begin switching over from cones to rods and vice versa. Your rods actually prefer moonlight. The rods in your eyes, that is. They pick up motion well, but they’re not so great at detail.
1. Scan and tilt
Once night vision kicks in, you might wonder why you can spot a corn chip on the ground from the corner of your eye and then fall over a table right in front of you. That’s because you’re stupid. No, but seriously. That’s because rods are located further out from the center of your retina. This is your night blind spot.
So if you want to survive at night, you need to employ a method commonly used by soldiers to detect things at night. Other than night vision goggles.
Turn your head side to side and up and down. You can use this method to identify something or someone without looking directly at it. As soon as you look directly at it, you’ll encounter your night blind spot.
If you’re in a situation where you’re at risk of being detected, then move your eyes from side to side instead of your head so you don’t give away your position.
2. You’re not a moth, stop looking at bright lights
Photo by Mathijs Delva
Looking at bright lights – a street lamp, car headlights, a UFO about to abduct you – is a natural reaction. Fight it. As soon as you look directly at a bright light … bye bye night vision. Then you’re back at square one and you’ll have to spend another 30-45 minutes adapting to the dark again.
Some lights will blind you more than others. On the least blinding edge of the spectrum is red light. The military use red lights when operating at night. Ship captain’s instruments are lit with red light. This is not because their favorite color is red, it’s because your rods are not very sensitive to red light. The center of your retina, the fovea, is packed full of red sensitive cones. It also happens to be the same area that has no rods. This is why using a very low intensity red light does not destroy your night vision. In fact, pilots are known to wear red-tinted glasses in low light conditions if they don’t have time to sit in perfect darkness prior to night operations.
The rods in your eyes are most sensitive to blue-green, like the green of a traffic light or the blue of a car headlight. If you don’t have time to stop a bright light destroying your night vision, cover one eye. You see? The pirates were onto something!
3. Approach concealed areas from a wide angle (that’s what she said?)
If everyone did this in movies, no one would ever get kidnapped. And there would be 63% less karate chops.
Giving ye dubious abode a wide berth is critical at night, when you need every sliver of a second for your reaction time. If you’re walking down a street and you’re sticking close to the shop fronts, you’ve become an easy target for an opportunistic assault from an alcove, doorway or alleyway. Or even just a simple corner. It’s about as smart as pointing a gun at someone who is within arm’s reach – don’t do it unless you want to be disarmed, or at least attacked.
- Put as much distance between you and potential hiding places
- Walk curb side to see into alcoves and doorways before it’s too late
- Walk on the opposite side of the street to streetlights for safer, more even lighting (unless you’re a deadly ninja assassin trying to conceal yourself, in which case stick to the shadows)
- Take corners as widely as possible
- Check corners for shadows – does that lamppost have a shadow? Yes? Is there a human shadow next to it? How far away?
4. Does eating carrots improve your night vision?
No. This is a myth that originated from a British disinformation campaign during World War II to throw Nazi Germany off the scent of their new radar technology.
If you’re suffering from Vitamin A deficiency then your night vision is likely to be poor. Red meat, eggs and liver are rich sources of Vitamin A (retinol) that can help recover your night vision. Vegetables and fruits have smaller amounts, but are helpful.
5. Does squeezing your eyes tightly improve your night vision?
This is a common myth in special forces: squeezing your eyes tightly for several seconds prior to entering a dark environment will boost your night vision. This appears to have a mostly psychological effect. Closing your eyes will certainly kick your night vision in, but you’ll still need to wait 30-45 minutes to attain full night vision. Squeezing them won’t speed things up.
Part II tomorrow, special ops trainees!
If you can’t wait until tomorrow for more, try this.
Tagged: adorable bunny, pirate dog, secrets, special ops, techno-thriller, Twilight
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