You’re home alone and feel a presence behind you — only there’s no one there. Do you brush it off as a trick of the mind or are you part of the 45 percent of the U.S. population who think, just maybe, it could be something else? A recent Swiss study has offered a more scientific explanation for feeling something that just isn’t there, suggesting it really is all in our heads. Although these findings aren’t about to suddenly convert believers into skeptics, at the very least, they may open our minds to the idea that the line between reality and perception is much more abstract than commonly believed.

Humans’ fascination with unseen entities has existed from the dawn of time. A team of researchers from École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland were particularly interested in not the appearance of ghosts but rather the sense of feeling you’re not alone, especially in individuals who had recently gone through traumatic experiences or suffered from a psychiatric condition. The team set out to see if it was possible to recreate a similar experience, only not in a spooky abandoned house but in a controlled laboratory.

They first analyzed the brains of 12 patients with neurological disorders who had experienced some sort of paranormal experience involving an “apparition.” According to the press release, the majority of the patients were epileptic. MRI scans revealed that on a neurological level, three regions in the patients’ brains had significant interferences: the insular cortex, parietal-frontal cortex, and the temporo-parietal cortex. These regions are known for their involvement in self-awareness, movement, and the sense of position in space, all extremely important in an individual’s perception of their own bodies.

The participants were not told of the true purpose of the experiment in an effort to obtain the most genuine reactions. In the first experiment, the scientists tested the participants’ spatial discrepancy. A robotic device touched the volunteers on their back, synchronizing their movements with the hopes of creating confusion. Amazingly, the participants' brains were able to adapt to the “dissonance” experiment and confusion was averted.

The researchers then stepped their experiment up a notch, introducing a temporal delay between the participants’ movement and the robot’s touch. It was then that the combination of the asynchronous conditions, distorting temporal and spatial perception, succeeded in recreating the illusion of a ghost.

Although you may be familiar with the God Helmet, which is able to induce the feeling of a higher presence in non-believing wearers by altering the electromagnetic field in their brains, this is the first time that a study has succeeded in reproducing the sensation of actually feeling an unknown, unseen, presence. The study is now available in the online journal, Current Biology.

The unseen presence was felt so strongly that many of the participants were truly unnerved and asked that the experiments be stopped. To Olaf Blanke, lead researcher of the EPFL team, this was a sign of success. “Our experiment induced the sensation of a foreign presence in the laboratory for the first time. It shows that it can arise under normal conditions, simply through conflicting sensory-motor signals," Blanke explained in the press release.

While it’s hard not to take this study’s finding as scientific proof denouncing the existence of ghosts, in actuality the researchers were more interested in better understanding some of the more extreme symptoms of patients living with schizophrenia. Many patients with this condition suffer from extreme delusions of the presence of alien entities that they can feel and hear but often fail to see.

“The robotic system mimics the sensations of some patients with mental disorders or of healthy individuals under extreme circumstances. This confirms that it is caused by an altered perception of their own bodies in the brain," Blanke added. These findings will go on to help expand scientists' understanding of this extremely debilitating condition.

Source: Blanke O, Pozeg P, Hara M, et al. Neurological and Robot-Controlled Induction of an Apparition. Current Biology. 2014.