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Re: [Phys-L] Variations in People’s Sense of Direction

In bird orientation experiments with Helmholtz coils, it was sometimes reported that line ripple of the coil drive was associated with failure of the test subjects to orient with the magnetic field. This hints at a short sensory integration time ~ perhaps as small as 8 milliseconds. The magnitude of the geomagnetic field at mid-latitudes is about 470 milligauss or 47 microtesla.  People with desk jobs typically soak in a steady field orientation, which may well be disturbed with line frequency magnetic field effects, so that a proton - precession magnetometer may need to be removed to a location with a  steady field to register the characteristic evanescent tone.I have inquired of a person with well-developed orientation awareness, how she "did it". She reported that she maintains an internal map which tracks her changes in heading. When measures are taken with human subjects to provide an initial disorientation i.e by walking blindfold into a novel room, and being turned in a random sequence; they typically cannot reliably point to a landmark direction or to North. Avoiding rooms with walls oriented N-S , E-W is one obvious way to avoid a 25% success rate at orienting.At least in birds the consensus has been that they will integrate whatever cues are available, which may include visual UV sky striations,  very low frequency sound source direction sensing to  emissions from mountain peaks hundreds of miles distant, characteristic odors, star-field orientation, landmark memorization, as well as geomagnetic field sensing.   This suggests that no one source may be so dominant as to avoid the need to integrate multi-modal cues.
On Monday, May 10, 2021, 07:22:39 PM CDT, Bill Norwood via Phys-l <> wrote:

Many thanks, Zeke, for the corrections and new-to-me information.

I had forgotten to mention in my earlier post that my then-wife also spent many years teaching while seated at grand pianos, but I do not know how those pianos were oriented relative to the ones she grew up with.

I should have remembered that the strings do not all run in the same direction, having done touch-up tuning for my then-wife’s grand pianos for many years.

I also had once removed all of the strings and the steel frame from her 6-ft Rud Ibach Sohn piano (if I remember correctly) so that it would be light enough to move without using professionals. Not a bright idea, I’ll admit, but dollars were scarcer those days.

My daughter, Jenna, cc’d, has suggested surveying pianists and piano teachers to learn whether they have a better sense of direction.


Bill Norwood
Physics Dept.
U of MD at College Park
1966 - 2018

Sent from my iPhone

On May 10, 2021, at 5:21 PM, Marc Zeke Kossover <> wrote:

The strings aren't all in the same direction on a grand piano. The longest  strings are at an angle to the rest of the strings. You can see a picture of this here.

Interestingly, the frame that holds the strings is really massive for a number of reasons. With tension of the approximately 230 strings pulling in adds up to about 2x10^5 N of force. Though measures are used to try to keep the tension even by changing the length of the strings and winding the bass strings with copper, the forces aren't all pulling in quite the same direction. I'm pretty sure that the frame outweighs the strings by a margin otherwise things would get exciting.

Still cast iron and steel has been known to get a residual magnetic field via the earth's magnetic field and vibrations, and I wouldn't be surprised that a piano kept in the same position for a long time might develop a field aligned to the earth's.

I had a steel filing cabinet in a classroom where I once taught that had been stuck into a corner for 50 years by the time I arrived. When we moved it, we could detect a small but measurable field with a Hall Effect probe that deviated from the earth's field.


On Saturday, May 8, 2021, 8:40:32 PM PDT, Bill Norwood via Phys-l <> wrote:

Hi Phys-L ‘ers,

No one responded last week when I suggested, in the context of the discussion about sharks’ sense of direction, that the variability in people’s sense of direction might be due to differing amounts of iron in their bodies.

Ok, here is another of my quarter-baked theories:

1. I have no sense of direction - once I make one 90 degree turn I am lost.

2. My son just informed me that his mother, a concert pianist, who did little other than practice on grand pianos since the age of four, had an extraordinary sense of direction.

3. Let’s think about it:
  a. Her being stationary and in the same position relative to the grand piano for tens of thousands of hours.
  b. The local earth’s magnetic field lines being guided, all in the same direction, by the piano’s 200 or so steel strings and tending to pass thru the pianist all in the same direction.
  c. The piano(s) were positioned in the same orientation for decades. (Not 100% sure of this)(Sometimes she did two-piano work, where the strings in one piano were parallel to the strings in the other piano.
  d. So, if she had any iron in her body, and we all do, that iron would experience torque from the earth’s magnetic field lines.
  e. The vibrating of the strings as she played would have caused a shaking in the magnetic field lines which would have shaken the iron particles in her body so that they would more readily “fall into place.”
  f. Did I get most of that right?


Bill Norwood
Retired Sep 2018
Physics Dept
U of MD at College Park

Sent from my iPhone
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