If you have ever had the feeling of being watched, you are not alone. Individuals with neurological problems experience these feelings all the time, which can be easily explained by scientists. What is not easily explained is why normal people, with no record of any sort of brain disorder, could also experience this same phenomenon.
Published in the journal Current Biology, a new study demonstrates how scientists used robots to simulate these feelings of “ghost in the room”. In this study, researchers were able to detect where these feelings come from, even in perfectly healthy individuals.
Exactly 12 patients were studied by a team led by Olaf Blanke of Ecole Polytechnique Federale de Lausanne. These patients were stricken with epilepsy, tumors, strokes and migraines, which caused them to sense “presences”, that weren’t really there. Scientists understand that the damage caused by these disorders is what ultimately led to the sensory hallucinations, and have pinpointed the exact areas of the brain that were affected – the temporoparietal, insular, and frontoparietal cortex. This was found through the use of brain imaging.
Since these different areas of the brain have various duties, it is understandable that signals are off. The brain, in actuality, is failing to send the correct signals to the limbs and vice versa. Our limbs provide the simple information about where we are in space, as well as in time.
The effects on the healthy brain
It is easy to understand why sensory hallucinations, such as feeling as if you are not alone, are experienced by those who have neurological problems. It is not, however, easy to understand why healthy individuals can sense the same thing. The answer revolves around confusion. Healthy people can get confused by the signals they are receiving. For instance, when the signal is coming from their own body, they can attribute the signal to a ghostly presence.
As Blanke states, “You are convinced there is something there, but you cannot see or hear anything.”
The robot ghost
So, the experiments were aimed to understand why these signals were getting mixed up. This is where the “Master Slave” robot was implemented – in order to create physically impossible sensory conflictions. The hallucination seems quite simple, really. The test subjects actually thought they were reaching out and touching their own back. In reality, the recruits were manipulating a program in front of them, which, in turn, moved a pair of robot hands behind them. Basically, the exact same movements were being mimicked behind the subject.
At some point, there were delays, which made the sensory hallucinations much worse. When the robot sensation was not poking the back of the test subjects, they were hovering quite close, making the patient feel as though someone was behind them. To resolve the spatiotemporal conflict in their brain, the researchers convinced the test subjects that the feeling was coming from the “other” in the room. When the subjects were told that many people were in the room, they believed this too.
The robotic test proved to be very successful with creating sensory hallucinations in healthy test subjects, even to the point of frightening them to stop the tests immediately. Creepy, huh, this doesn’t completely explain the phenomenon, but maybe these tests can even help us understand mental disorders and solve issues deep within the human mind that have stumped us for decades.