How’s
your eyesight? Good? Fair to middlin’?
How’s
your eyesight underwater with no diving mask on?
How
about if I told you there may be a way to gain a bit of improvement in both
above-water and below water environments?
An
improvement that calls for a remarkably short time investment on your part?
Stay
with me as we learn a thing or two from the Moken.
The
Moken [literally “sea people” or “sea nomads” or “sea gypsies”] are an Austronesian
people that inhabit the 800 some odd islands of the Mergui Archipelago that are
claimed by both Burma and Thailand.
The
Moken garner almost their entire livelihood from the Andaman Sea. You may have read
about them in the pages of National
Geographic or seen them in videos making lengthy hunting dives free of breathing
apparatus, diving fins, or diving masks. Images of them moving agilely about on
the sea floor are beautiful and inspire wonder [and a bit of envy in this
viewer.]
The
human eye has evolved to be a rather delicate and precise viewer of the
above-water world but for those of us who can even keep our eyes open beneath
the water’s surface we find that we’re lucky if we can see a mere three feet in
front of us.
So
how is it that the Moken, spears in hand, are able to hunt beneath the surface
and make precise spear-strikes with no diving masks?
Experienced
spearfishermen and scuba-divers know that even with diving masks there is a bit of double refraction going
on as the atmosphere between the cornea and the retina creates one bend of
light and the air between the glass of the diving-mask and the cornea creates a
second bend spawning a distortion of distance and angle that must be corrected
for. This correction can only be made with experience.
And
yet, the Moken do all this just fine without a diving mask.
Is
this a genetic adaptation to their environment specific to the Moken, or is there
something else going on?
Anna
Gislen, Eric Warrant, Marie Dacke, and Ronald Kroger, all of Lund University in
Sweden devised an ingenious experiment to divine whether underwater visual acuity
was indigenous to diving cultures such as the Moken, or is there some skill to
be learned. A skill that could be trained and used by anyone.
They
first tested just how keen the Moken’s eyesight is beneath the water using the
Pelli-Robson chart which tests for visual contrast, our ability to distinguish
shapes, a major need when hunting underwater.
They
then gathered subjects not of the Moken [European and Thai] and submitted them
to the same tests in a pool environment that mimicked the conditions of the
Andaman Sea.
Acuity
at 3-6 meters, no real difference between the test subjects and the Moken.
Once
you get to 9-12 meters, the Moken still see just fine, whereas the test
subjects are out of the game.
The
test subjects are then ushered through 11 training days spread out over a
1-month period. In these sessions, they dive to the bottom of the pool, and
press their faces to a viewer where they are presented with various forms of
Pelli-Robson charts as well as having a water-proofed video camera record pupil
dilation.
It
was surmised by the researchers that they Moken are able to voluntarily
constrict pupils enabling them to improve contrast resolution underwater.
Initially,
the subjects were experiencing no pupil change, but by the end of the training pupil
change was easily noted being engaged in by all.
How
did they foster voluntary pupil-change? We’ll get to that.
First,
how did they do by the end of their training session?
Did
underwater vision improve?
After
the 11th session, there was pupil change in all and an improvement
in underwater contrast performance of 27%, with the least performing subject
coming in at a 17% improvement.
17-27%
improvement in 11 sessions in one-month is nothing to sneeze at.
But
get this, the subjects were retested after four months during which there was zero training sessions. At the re-test
the pupil contraction was automatic, and the improvement comparison was 57%!
The
subjects at this point were on par with the Moken test-figures and some
surpassing them.
So
clearly, we are looking at a learned adaptation.
Think
carefully about this...
How
many areas of physical training can you think of where you can train for 11 sessions,
see improvement, take 4 months off and still improve?
Exactly
how does this occur. The answer is fuzzy, but these are surmises.
The
improvement during non-training is chalked up to consolidation or reminiscence,
which is another way of saying that the 11-sessions acted as neural pathway
training cementing a skill, as when we learn to ride a bike and can pick it up
again after years of non-bike riding.
It
is also surmised that a bit of blurred contrast training can be carried into
the above-water environment. “Rosenberg et al. (2004) noticed an improvement in visual
acuity in myopic subjects after only 3 h of exposure to blur.”
This is above-water blur exposure, as in decreasing Kindle font size, moving
the print of a physical book just to the point of blur aka “print-pushing,”
etc. [More on this another day, with a few unique ideas on vision-training from
other indigenous cultures.]
So, beyond the apparent “work with the task of contrast resolution
underwater until it sticks” were there any specific hacks to pass along?
Indeed, there are.
The subjects learned to cross their eyes when focusing on
the contrast tasks, this led to pupil constriction. The constriction increased over
time, i.e., exercise/practice, or skill-consolidation.
A subject who was unable to cross their eyes, compensated
by looking upward and/or learned to cross one eye.
The eye-crossing seems to lead to pupil constriction and
sets the stage for building a bit of increased visual acuity both in and out of
the water.
There you have it: An inspiring people, the Moken, an ingenious
experiment, and a hackable skill that pays dividends in very little time.
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