Are humans sensitive to the planet's magnetic field? Some are, but even those with the capability are not aware of their "sixth sense."
Magnetoreception is a common trait among many animals, but humans have never been shown to display this ability until now.
Researchers Design Highly Controlled Environment To Find 'Sixth Sense'
In a new study published in the journal eNeuro, researchers reveal that the human brain is capable of sensing the Earth's magnetic field.
Joseph Kirschvink, study author and geophysicist from Caltech, explains to Gizmodo that the research team focused on brainwave activity for the study.
"If the brain is not responding to the magnetic field, then there is no way that the magnetic field can influence someone's behavior," he says. "The brain must first perceive something in order to act on it — there is no such thing as 'extra-sensory perception.' What we have shown is this is a proper sensory system in humans, just like it is in many animals."
Kirschvink and other researchers designed a special chamber, which blocks extraneous interference that could potentially compromise the findings. Inside this chamber, participants' brainwaves were monitored using electroencephalogram (EEG).
As the researchers write in Discover Magazine, the magnetic field shifts relative to the skull when someone turns their head in regular life. The brain registers no surprise, since it directed the movement. If another person turns the head, the body will still register a change in its position in space from vestibular clues.
For this study, the researchers controlled the magnetic field around the participants' heads without alerting the brain with movement or other spatial cues. Only the magnetic field shifted — and the scientists wanted to see whether the participants will be able to register the changes.
None of the participants reported sensing any changes in the magnetic field, but the EEG findings reveal a wide range of reactions. Some brains barely took note of the changes, while four of the 34 participants showed strong brain responses to the rotations of Earth-strength magnetic fields.
Specific Responses In Few Participants
Brain responses were only triggered when the vertical component of the magnetic field pointed downward at around 60 degrees. Since this is a natural occurrence in Pasadena, California, the researchers suggest that responses are connected to the brain's natural stimuli.
Previous research shows that it's a similar mechanism to a number of animals who only respond to magnetic signals that are relevant and common in their environment.