>She did notice, however, that the European kids would experience red eyes, irritated by the salt in the water, whereas the Moken children appeared to have no such problem.
There is a trick that can help reduce eye irritation by salt, which may explain this : Eyes must be closed when crossing the interface between air and sea (that's usually instinctive) and also closed when crossing from sea to air (usually counter intuitive).
The reason is the protective tear film get broken upon crossing when eye is open.
Remembering the trick before the salt get in the eye is also a trick to remember. Because once film is broken it needs either time to regenerate or rinsing with non salty water to regenerate.
You also need to avoid touching the corner of the eyes when your hands are covered of sea water. That usually the first reflex once the eyes are irritated, (if you must touch the corner of your eyes do so with your eyes closed). This trick is easier to learn, because when your eyes are not irritated and you touch the corner of your eyes with salty hands the irritation is instantaneous.
I learned to swim without goggles and could see under water. It went away when I started wearing goggles. I can remember trying to go without and was shocked by how blurry the water had become.
Yes, reading this article I also remembered having no problem as a kid who grew up next to the beach. As an adult many times removed from that life, I now need goggles when I go swimming. It's a shame the body loses that adaption so easily.
I thought my memories of seeing in the water were false. I used to swim in deep crevasses in the river by my home and look for glimpses of trout and steelhead. I could dive down and get crayfish after spotting them from fairly high up. I remember needing to equalize many times and my body would lose buoyancy. Sometimes I'd lay on the sand or rocks and those are my most vivid memories of seeing under water. The algae on the rocks would be swaying, sunlight refracting all over, and the sound was nothing but a gentle, deep, soothing vibration of the water tumbling over stones.
I recall my vision being far from perfect past 6 or 7 feet, but still pretty usable.
These days I need a low volume mask and contacts if I want to see anything in the water.
It's an adaptation? Huh, never thought about it. I would go swimming in the sea when I was a kid without goggles, could see everything clearly. Nowadays it hurts opening my eyes underwater, I assumed it was just polluted as hell (by all reports it is)...
Part of the study claimed that in a month of diving exercises you can replicate this clarity of vision underwater in European (and presumably any) children. That should be easy to reproduce. The part about a speculated adaptation to better tolerate salt water in the eyes, less so.
As far as I know the eyes don’t deliver perfect imagery but the brain does a lot of image processing to make the image usable (similar to a camera where what the sensor sees is pretty distorted and is corrected with software).
So I would think you can train your brain to process what you see underwater clearer with a lot of practice.
I had a normal vision since I was born until I got an artificial lens in my right eye at 9 y.o. to deal with glaucoma caused by trauma. As you may guess, this new lens is not even close to the biological, as it has different elasticity and light refraction properties. The picture from my right eye is heavily abberrated, but my brain applies inverted abberation to the left eye's picture to have an almost perfect binocular vision. It wasn't like that on day 1 from operation, but progressed over a couple of years. Same thing with lens focus - it was 20/200 when I leaved the hospital, 20/30 after a year and 20/20 in two more, although the abberations couldn't be fixed.
Similar experience, though kind of in reverse. I was born with a congenital cataract in my left eye, and my brain learned to either correct or tune out the picture from that eye. When I closed my right eye, the left picture was significantly darker and had a large black spot near the center, but with both eyes open I had very good (I guess? Hard to compare when you've known nothing else) vision.
I got the bright idea to have cataract surgery in my late 20's despite the cataract never really bothering me. While the sight in my left eye is now objectively "better", the surgery actually made my binocular vision worse because my brain isn't used to the new type and degree of aberration, and so doesn't yet know how to correct for it. I'm a few years out from the surgery and it's definitely better, but I kind of wish I'd left well enough alone.
Consider that your brain already has to do this anyway even with all-natural eyes. It receives an independent image from each separate eye, so it has to line the two images up with each other in order to produce binocular vision. It's not as if your eyes come pre-calibrated or something, and even if they did, your skull grows throughout your life, so the alignment of eyes relative to each other must change over time, requiring your brain to gradually recalibrate. So it makes sense that the brain would be able to recalibrate to an artificial change in your vision as well.
With blurry data, there's not much you can do. The adaption is about to change both the pupil's size (constricting it, like in a pinhole camera) and the lens' shape.
I've tried to learn how to do this myself with very limited success. If I try to force my eyes to become blurry and then unblurry, I can notice some improvement in my ability to resolve images underwater. But this probably takes a lot of practice, and my lens is already starting to harden with age.
The brain does an awful lot with blurry and outright missing data. Look at something in your peripheral vision and name the colour of it, that's the brain filing in information that your eyes can't see. We only have good eyesight in a surprisingly small region directly in front of us.
> The dividing line between near and mid peripheral vision at 30° radius is based on several features of visual performance. Visual acuity declines by about 50% every 2.5° from the center up to 30°, at which point visual acuity declines more steeply.[18] Color perception is strong at 20° but weak at 40°.[19] 30° is thus taken as the dividing line between adequate and poor color perception. In dark-adapted vision, light sensitivity corresponds to rod density, which peaks just at 18°. From 18° towards the center, rod density declines rapidly. From 18° away from the center, rod density declines more gradually, in a curve with distinct inflection points resulting in two humps. The outer edge of the second hump is at about 30°, and corresponds to the outer edge of good night vision. - https://en.wikipedia.org/wiki/Peripheral_vision
The question is whether your input is really blurry or the brain just doesn’t decode it right. A few months ago I remember reading about a method to improve eyesight by looking at things and retraining the brain. I don’t remember the details but it really worked for the author. The only problem was it was extremely boring, tedious and consumed several hours a day. But it worked. Wish I could find that article again.
There’s some really interesting stuff around this, once you start digging. I’m aphakic in both eyes (no lenses; they were removed as cataracts when I was a kid) and was blind as a child through some of the critical period of vision development. That left me having what I think can be described as bilateral amblyopia - essentially two ‘lazy eyes’, though that’s not really a good description in the sense that ‘lazy eye’ seems to be commonly misunderstood.
So the weird thing is that both my eyes have a visual acuity around 20/120 or worse; that’s with correction (glasses) and it depends on the day (tiredness/dryness/etc) — but having lived this way my entire life essentially, I find it REALLY difficult to describe what it’s like to people. People think things off in the distance must be ‘blurry’, but that’s not the case at all. It’s more like ‘less detailed’, like if you turn the resolution and texture detail down. It’s not like an unfocused lens at all. There are studies I’ve found that seem to back this up.
Another problem I have that’s related is a nystagmus - both my eyes oscillate involuntarily from side-to-side, separate from the normal saccades (rapid eye movements) that everyone has. You’d think I’d see the whole world oscillating from side to side - but I don’t at all. I don’t usually even notice these movements when I look in the mirror, though I can see them if I’m looking at a video of my own face.
That is, most of the time. There’s one really strange failure mode I’ve observed - PWM-controlled small LED lights or segment displays like on a digital clock, particularly if they’re red but green as well, in a dark room. If it’s dim enough that I can still dimly see what surrounds the display, I can sometimes notice the LED oscillating left and right, WHILE THE STUFF SURROUNDING IT STAYS STILL. It’s really freaking weird!
I often see something like that when I'm driving and stop behind a car that has LED tail and brake lights including an LED brake light above the rear window.
If I look at the car's rear trunk lid and hold my eyes still for a few seconds, the raised brake light starts moving up! (Or down, I don't remember which direction right now, but I think it's always the same direction.)
And it's not like everything in my vision is moving with it, that one raised light is moving all by itself. And it keeps moving and moving in the same direction, but somehow stays in the same place.
It's a strange experience, almost like a Shepard Tone of vision.
I have perfectly normal vision (no nystagmus that I know of), and still notice PWM LED displays moving relative to the surrounding microwave, when my eyes move around.
I'm nearsighted, but as a kid I had an enormous range of focus with my eyes.
I could rest my finger at the end of my nose and clearly see the whorls in my fingerprint. I could feel the muscles in the front of my eye contracting when I did this.
That went away over time, even as my prescription became much more nearsighted (I'm almost 9 diopters now)
The eyes don’t deliver imagery at all. They deliver a signal that’s more like a million track audio recording. It doesn’t become imagery until interpreted by the brain.
If you hooked a camera up to a newborn’s ears and microphones to their eyes, the baby would learn to see imagery though their ears and hear sounds through their optic nerve.
The data quality would be horrible, but they’d still see and hear.
It’s the structure of the world (and our relationship to it) that creates meaning in our minds, not the structure of our brain. Although our brain is structured to get clearer signals through certain parts.
>They deliver a signal that’s more like a million track audio recording. It doesn’t become imagery until interpreted by the brain.
For many on HN, that's the way they are used to thinking of imagery, as a big array containing information about how strongly a grid of sensors was stimulated.
I have moderate hearing damage in one of my ears, mostly in the midrange according to audio graphs. Too many raves without hearing protection.
I have lost the ability to hear people in bars, or the 200sqft tile room where the elevators are at work, or when people are holding multiple conversations in a conference room.
I'm fortunate that I was able to identify the problem and prevent it from getting worse. It's amazing how just a small amount of missing information has effectively broken the "noise canceling and directional isolation" "software" of my brain.
This will sound paradoxical but... Wearing earplugs can really help.
Hearing loss isnt so much an inability to hear "quiet" (despite how hearing tests are performed) as it is a los of dynamic range. By wearing earplugs you can lower the volume of all conversations and prevent "clipping", so to speak.
Try it! Next time you're having trouble hearing someone try to plug your ears with your fingers.
An older guy from the rave scene once taught me this without explaining the process at all.
When we'd be out and loud music was playing and somebody couldn't hear what he was saying to them, he'd lean in, speak more softly and place a finger lightly on the front part of their ear (so as to not put his finger in their ear).
He was always much easier to understand one he had done that, and we all picked up the habit. We weren't sure if the finger acted as a conductor, or what the explanation was, but reducing the dynamic range seems like a really good explanation.
I actually do. I have a couple of different silicone plugs with different capabilities, including hifi, low att, etc.
They work, but it's annoying wearing them in all the time. I also have Sony XM3 adjusted to reduce most (not full) noise with anc and that helps quite a bit as well.
I have big problems understanding conversations in bars or larger groups where other people seem to be able to follow without problems. But based overt hearing test I have taken my hearing is actually very good, way better than average. I believe that somehow my brain doesn’t assemble the input correctly so even though the right signals are there I am not using them.
Based on musical training, I have a fair amount of belief in that we don't use much of our system. Both actuating and sensing. That said, I'm really not sure what to do to improve things regarding vision. Stare at the sun ? jk.
I grew up in the mountains, and only went swimming a couple of times per year at the ymca. I also recall having very clear vision underwater, and being confused as to why the adults weren’t doing such an enjoyable thing.
I didn't realize that this was a special skill. I've always been able to see underwater, as long as the water is fairly clear. Depending on the pool I sometimes got irritated eyes, but it never really bothered me to have water in my eyes. Maybe that's why I never really had issues with my contacts either?
Not OP. When I was a kid I could only see blurry shapes underwater, until one day it was like something clicked and suddenly I could see as clearly as in air. I have no explanation, just an anecdote, and my vision is now poor everywhere.
I have always swam underwater with my eyes open (in lakes, never tried it in seawater) but I cannot bring things into focus. I see blurry shapes that tell me where the rocks are, that’s all. You can bring things into focus like in the air? Do you have perfect vision in the air, or nearsighted, or farsighted?
Yeah I can bring things into focus. I’ll have to jump into the pool this weekend and test it out a bit more. Also I’m very nearsighted. Without contacts in I probably see like the average person does in water.
The kids had to dive underwater and place their heads onto a panel. From there they could see a card displaying either vertical or horizontal lines. Once they had stared at the card, they came back to the surface to report which direction the lines travelled. Each time they dived down, the lines would get thinner, making the task harder. It turned out that the Moken children were able to see twice as well as European children who performed the same experiment at a later date.
With the exception, I suppose, that with eye irritation it would be more difficult to complete the tests in the first place.
>She did notice, however, that the European kids would experience red eyes, irritated by the salt in the water, whereas the Moken children appeared to have no such problem. “So perhaps there is some adaptation there that allows them to dive down 30 times without any irritation,” she says.
I'm not sure it needs to be an adaptation (in a genetic sense), I think like most things our bodies just get used to it. I used to open my eyes underwater when swimming at the beach as a child on holidays, but not an adult. Having a salt water pool at home probably helped, but now that I rarely go to the beach it stings.
Right, I just mentioned that sometimes I got irritated eyes specifically in overly chlorinated public pools or swimming in indoor pools. Since I know that is a common complaint.
Not sure what you consider it "this sort of thing", but native speakers of Australian aboriginal language Guugu Yimithirr have nearly superhuman sense of direction. They can automatically tell where is north, south, east, and west.
I believe they don't actually use left and right, but use the cardinal direction instead. So it's something they need to be constantly aware of. Ie: their kids song would go "Put your south hand in, put your south hand out.."
Indonesia’s Bajau people, who for generations have spent the majority of their days diving and hunting underwater, have genetic adaptations that include spleens that are around 50% larger than those of their land-based neighbors. https://www.sciencemag.org/news/2018/04/indonesian-divers-ha...
You'd imagine this would be basically a death sentence, but she's made it to old age. She also has a lack of adrenaline response, so is basically super chill. Hard to argue this is a beneficial mutation, but perhaps as technology evolves we could self-monitor artifically and not have to worry about these deeply unpleasant physiological warning bells?
TLDR; Children's visual acuity underwater increases with practice. There appears to be nothing special about the Moken children other than their time spent underwater using their eyes.
> She did notice, however, that the European kids would experience red eyes, irritated by the salt in the water, whereas the Moken children appeared to have no such problem.
That's just an observation and is there is nothing in the article to indicate it's not covered under "other than their time spent underwater using their eyes" is there?
The title of the research paper is "Visual training improves underwater vision in children".
That's a pretty bizarre basis for differentiation - I grew up swimming in the ocean, eyes wide open. never once did I get red eyes. Chlorine in pools is a different story.
It's not just salt, it's other pollutants. The difference between swimming in clear Croatian beaches and the average German (or Italian) waterbody is noticeable.
There is a trick that can help reduce eye irritation by salt, which may explain this : Eyes must be closed when crossing the interface between air and sea (that's usually instinctive) and also closed when crossing from sea to air (usually counter intuitive).
The reason is the protective tear film get broken upon crossing when eye is open.