Can Humans Sense Magnetic Fields?

Okay, they're about to lock me in here and then use these electric coils to make magnetic fields that rotate. They're roughly the strength of Earth's magnetic field and we'll see if my brain is picking up on the fact that the magnetic field is changing. The whole time I'll have my eyes closed; it'll be pitch black in here, basically no stimuli except for the changing magnetic field, and I'll keep my head perfectly still facing forward. That sound good?

• Yeah, gonna take about eight minutes. Eight minutes, perfect. Okay, I'm ready when you are, but before we do this, let's meet the researchers. Can you introduce yourself?

• Introduce myself? Ah, my name is Shin Shimojo. I'm a professor in neuroscience and experimental psychology at here Caltech Biology. Connie, you are the first author here, and your paper has just been published when this video goes out. So what is the setup of the paper? How do you set this up?

So basically, we wanted to see if humans have any brain response to a magnetic field. It has long been recognized that certain bird species have a remarkable ability to find their way home, hence the use of homing pigeons to carry messages for us. Their impeccable sense of direction is owed in part to their ability to sense the Earth's magnetic field, but they are not the only animals that do this—certain bacteria, bees, salmon, turtles, rats, dogs, whales, cats, and all of them are known to have a magnetic compass.

Dogs, known to poop with their bodies oriented preferentially north-south, have even been trained to locate bar magnets. Given a choice between three containers, they were much better than chance at identifying the one containing the magnet. In fact, they were much better at finding a magnet than finding a food treat under similar conditions. Given all these examples, it seems more likely that humans should have the ability to detect magnetic fields.

And if you're wondering how humans could physically pick up the magnetic fields, consider that magnetite crystals have been found in the brain that closely resembled those of magnetically active bacteria. My colleagues in neuroscience said, "Wow, this is hard to believe, you know, this is impossible," but lots of biologists and geophysicists said, "Well, it's a matter of course; humans are not exceptions among all those mammalian species." But up till now, the evidence has been contradictory and controversial.

So in the early 80s, Robin Baker did some studies where they took groups of students and drove them around in very convoluted routes around the English countryside. And they were blindfolded, and then they would stop the bus and ask the students to identify which direction they came from, so basically 'home,' and they got pretty significant results from that. Shortly afterward, maybe a few years afterward, this study was attempted again at Princeton University, and they did just a very similar experiment there, and they couldn't get significant behavioral results there.

That's a controversy—lots of positive reports and the failure of the duplication, negative data in neuroscience, as well. So let's step back and then see if there's any systematic, selective response from the brain to the magnetic field itself, not anything associated like vestibular things or visual scenes, swinging and stuff like that.

So this is the test chamber. I'll turn on the light—so this is our magnetic... is that the way we get in? Yes, that's the way. You have to crouch in. So I'm gonna crawl under there.

• Yes, and you sit down there... hang on a sec, hang on, this is too cool. I really like it. What.. whose chair is that?

It just happened to be... Joe's chair. Joe's reclining chair, and not used for this purpose, but it turned out it's very relaxing. The main reason for this cage is to shield the outside effect for one thing and also have a good control over the modified Faraday cage where electricity is running. Okay, so, and then there's no sound or vision or tactile or any other additional stimulation because we are tapping into a very subtle response of the brain at the subliminal, subconscious level.

It doesn't block the Earth's magnetic field. The Earth's magnetic field goes straight through this, and that's actually sort of what we want because inside the chamber we're not trying to override the Earth's field; we're just trying to redirect it, just to add a little bit of field here and here, remove a little bit there. And by doing that, we can smoothly move the field back and forth and move it in a way that relates to how someone might experience the field as they're sort of moving, you know, around outside.

So that's essentially what you're simulating in here, yes?

• Is you're making it as though my head is swiveling around in the Earth's magnetic field?

Yes, except that if you're actually doing it in the real world, then your vestibular system is also sending signals. We are not interested in contamination from vestibular signals, so we would like to generate artificially that kind of situation like this, however eliminating any other sensory modalities such as vestibular.

Can I hop in there and just have a look?

• Oh yeah, go ahead, of course.

• Okay, I mean I feel like for my job I have been in more weird soundproof boxes than most people. These black coils here, do these create the magnetic field?

No, so those are for a different experiment. So the magnet coils are actually these things. Those are the magnetic coils. And you can see there's four of these square coils—

• Yeah—

In all three directions, and this is a nested three-axis coil set, and it's designed to create a magnetic field in any direction inside the chamber, and in the center of the chamber where your head and torso is going to be. Mm-hmm, it's designed to create a uniform field, so a field with no gradients or curves in it.

I've brought a compass, and so I can just see if the magnetic field is changing; what's gonna happen when I sit in this room. Okay, that was a pretty dramatic shift. So there will be two kinds of rotations; one is clockwise and one is counterclockwise, and as a control, on some trials the magnetic field won't change at all. So we can compare on trials what happens after the field rotation versus trials where no field rotated.

So this is the sort of thing that I'll be experiencing, but in the dark?

• Yep. Now we're gonna want you to use your left hand to hold it here 'cause it's easier than the front, the cap.

Yep. On this cap, there are 64 electrodes, which will pick up the electrical activity of my brain, and you're sure this isn't just to make people look stupid?

• Oh, no, no, no.

When you're awake with your eyes closed, the dominant signal is called the alpha wave. In most people, it occurs around 10 Hertz. These little squiggles right here, they're happening at around 10 times per second; these are the alpha waves.

We are measuring your alpha wave, which is known to be an indicator of relaxing and sometimes even drowsy but not sleeping, and then when you notice something like in vision or audition or touch, your alpha wave is suppressed, and that is the signature of a brain detecting sensory signals and moving attention towards it.

So the goal of this experiment is to determine if a magnetic field rotation causes the amplitude of alpha waves to drop. I'm about to go into the cage; I'm gonna turn off the light. And then we just do this with a stool, turn off all the lights in the room, and we close the doors.

And throughout the experiment, I'll be listening in and watching the video for safety reasons. Can you hear me?

• Yes, I can.

I'm setting up the experiment. Um, we'll be starting shortly. Just wait for the 'ding dings.' The experiment is starting; you can see that's our starting point. In terms of direction, it will vary from two preset values; yeah, so you can see there, that was a field rotation.

This is like one of the more glamorous— ahhhh... there we go. That's what I was not meant to hit. Thank you. Sorry about that. I could see that happening. You could see that coming. Man, I was thinking about saying something to the camera. I can't wait to see the results, though.

This is a section of my raw EEG results. You can see that every three seconds, the field was rotated either clockwise, counterclockwise, or it was fixed, meaning it didn't change. Now it's impossible to draw conclusions just by looking at this, so the scientists average over all the trials in the different conditions and plot the alpha power over all the electrodes.

This is a recording from someone who is particularly sensitive to changes in the magnetic field. As I play this, watch how the clockwise and counterclockwise responses compare to the fixed field result. The recording starts before a rotation. The magnetic stimulus takes place, and now observe the post-stimulus response, particularly for counterclockwise; for this subject, the counterclockwise rotation resulted in a clear decrease in alpha power of at least three decibels, shown by the dark blue color.

This corresponds to a decrease in alpha power by around 50%. Now, here are my results. After the magnetic stimulus, my response to counterclockwise is clearly not as pronounced. But over time for clockwise rotations, my alpha power is reduced. I was told I was neither the most sensitive to magnetic fields nor the least sensitive; I was somewhere in the middle.

So the conclusion is that our brains have the ability to sense magnetic field change, but it's implicit and subliminal—it's a non-conscious part of the brain. This is just the first step to make sure that it's not theoretically impossible that our ancestors might have utilized this ability for their navigation. Even modern people like ourselves may potentially have it.

This will open up the window for the next stage of research as to how we could bring it to consciousness, how could we strengthen them, and how could we utilize it. As yet, it's unclear if anyone can actually make use of this sense consciously or subconsciously to help them navigate, but the study's authors point out that a surprising number of human languages lack terms like front, back, left, and right and instead use cardinal directions: North, South, East, and West.

Native speakers of such languages would refer to a nearby tree as being to their north rather than being in front of them. Individuals who've been raised from an early age within a linguistic, social, and spatial framework using cardinal reference cues might have made associative links with geomagnetic sensory cues to aid in daily life. In other words, people from such cultures may be conscious of their magnetoreception. They would be very interesting to test.

But if it turns out that this sense is no longer functional in humans, just a relic from our ancestors, it would be interesting to consider why we lost it. Maybe modern humans don't need it—that's one explanation. Another explanation is we are surrounded so much and exposed so much to artificially created strong magnetic fields, starting from the airplane cabin, headphones; some younger people are wearing this for 10 hours per day, including MRI scanners too.

So it's possible our internal compass may be a victim of our modern technology. This study does not show that magnetic fields have some kind of special influence on you; they don't cure diseases, they don't make you smarter. You can't communicate telepathically or something through them.

So these are the types of emails that Connie does not want to receive, just so everyone's clear in case you've got sort of a crazy idea. My hair still looks stupid. In case you have a crazy idea for what to do with magnetic fields and the human brain, this study does not support that.

• No, it does not support that.

It only supports that the human brain can pick up on the physical stimulus of the Earth's magnetic field, yup.

• Which, in itself, is a super cool finding.

It is a super cool finding; it's like the basis for future research because, you know, you can't have any behavior without some kind of something going on in your brain.