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The word "How?" springs to mind at this point.
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Inspired by [lurch]'s annotation on Magnetosensitivity in humans ([link]) I thought it
would be interesting to do a study of how people's internal compasses agree and disagree
with each other and with a real compass both over space and over time.
An app periodically asks the user via a notification
what direction they think is north.
(The user can also voluntarily submit data whenever/wherever they want.) This is
indicated by an arrow on the screen; the user rotates the phone so that the arrow points
in the direction they currently feel is north, and then taps to confirm. The app also asks
the user whether they're currently indoors, outdoors, in an enclosed vehicle, or other.
It then displays a real compass (using the phone's magnetometer, like compass apps
generally do) to show the user which way is really north, with an indicator on the compass
to show which way they thought was north. ('Real' north, obviously, must be compensated
because the magnetic pole and the geographic pole don't coincide; GPS or other location
data from the phone can be used to do this.)
The app also records the local magnetic field parameters, as well as ambient light, noise
level/spectrum, recent motion/vibration, and the angle at which the user held the phone.
These are all reported to the researchers. (It might also be interesting to record biometric
data like heart rate and walking pace, which could be facilitated by a smartwatch or
fitness tracker, or just by using the phone's camera and IMU.)
The researchers, using data mining techniques, evaluate the correlation between different
users' internal compasses at different locations on the map. Areas of high correlation and
areas of low correlation may be interesting places to survey magnetic fields, light levels,
sound levels, etc. in more detail to see if any of these is likely to be the cause.
People could, perhaps, be enticed to participate by gamifying it such that they can
compete with other users to have the most accurate internal compass. However, they
could just use a separate compass to cheat. Therefore, I think it would likely be better to
just run it as a thing where users participate because they want to contribute to science,
or by paying users a small amount per useful reading (somewhat like Google Opinion
Magnetosensitivity in humans
Mentioned in idea. Search the page for "135". [notexactly, Jul 22 2016]
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||This could be interesting inside caves or big
basements like the Chrysler tech center or the
||May have to be done in someplace other than the user's
home turf. Most people know their local directions.
||I like the idea a lot, but I don't think it will work at all.
||Humans may be magnetosensitive but, if they are, the sense is
pretty weak (at least in most people). For that reason, attempts
to confirm or deny the existence of this sense have to be
exquisitely well controlled to identify a weak signal against a
large background of noise plus non-magnetic directional cues.
||You almost certainly _would_ find a strong sense of northness
using this method, but most or all of the signal would be non-
magnetic. For instance, if you can see the sun (or have seen the
sun, and have a vague recollection of turning left twice on your
way into a building), you will have a strong idea of where north is.
If you've driven somewhere by SatNav, or using a map, you'll have
a rough idea of where some major features are. Even if you've
heard today's weather report, you'll have some subliminal idea
that the cold wind hitting your face is coming from the East. In
fact, there are probably a dozen known and unknown non-
magnetic environmental cues to northness, and all of these would
swamp any magnetic cues.
||Sadly, this is one case where the average of a huge amount of
data will not give you a reliable answer. The only good way to
test for magnetosensitivity is to put people in a closed room,
soundproofed against noise from that airport to the West,
blindfold them, turn them around umpteen times on a rotatey
chair, and then ask them to point north. So far, these tests have
given only very weak evidence of magnetoception in humans - far
weaker (at best) than that of, say, migratory birds.
||What would happen if you did it on one of the poles?
||One of the Ukrainians might be just as good.
||Yes, but then all you know is that you're facing the
||// You almost certainly _would_ find a strong sense of
northness using this method, but most or all of the
signal would be non- magnetic. //
||That's fine. I only want to see how people's senses of
direction agree and disagree, whether that's for
magnetic reasons or not.