14 DAY TRIAL // A paper published in yesterday's issue of the journal Current Biology details how, with the help of a robot, scientists with the Ecole Polytechnique Fédérale de Lausanne, a research institution in Switzerland, made a group of volunteers feel the presence of ghosts.
To get these people to feels as if an odd, invisible presence were standing right behind them, the researchers caused a mismatch between the sensory and motor signals received and processed by their brains.
The experiments, carried out in laboratory conditions, show that, contrary to what some people say, the alleged ghosts whose presence folks sometimes report feeling are no more and no less than illusions caused by the brain.
Creating ghosts in the lab
As part of this research project, scientists first blindfolded the volunteers and also asked them to put on headphones. They then made them stand in between two parts of a robot, of which one was in front of them and the other behind them.
Next, the participants in the study were asked to reach out in front of them and tap on a button. The robot part behind them recreated this movement, meaning that it touched the volunteers on their back in the same manner that they touched the button.
As long as the participants' hand movement matched the sensory input received from the robot time-wise, the volunteers felt quite at ease. Things got really freaky when the scientists induced a delay between the volunteers' and the robot's actions.
Thus, this temporal mismatch between the motor and sensory signals received and interpreted by the participants' brains resulted in a state of confusion concerning the source of the touching sensation. Simply put, the volunteers attributed the sensation to an unseen presence standing right behind them.
“For some, the feeling was even so strong that they asked to stop the experiment,” study leader and Ecole Polytechnique Fédérale de Lausanne scientist Giulio Rognini detailed the outcome of these experiments in an interview.
“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,” the researcher went on to explain.
It is understood that, of the volunteers involved in these experiments, some 30% reported feeling as if somebody were standing right behind them almost as soon as the sensory mismatch was induced. Some of them even counted up to 4 ghosts when in fact they were completely alone.
How ghosts only live in the human brain
Writing in the journal Current Biology, the Ecole Polytechnique Fédérale de Lausanne scientists argue that the outcome of this series of experiments just goes to show that ghosts only live in the human brain. Thus, they say that such presences are no more and no less than illusions.
The researchers go on to detail that, as shown by their investigation, folks struggling with psychiatric and neurological issues and those experiencing physical exhaustion sometimes feel the presence of ghosts simply because of altered perceptions of their own body.
More precisely, it is argued that even people who are otherwise perfectly healthy can feel the presence of an invisible entity when their brain fails to properly integrate information concerning the body's position in space and its movements.
“Our brain possesses several representations of our body in space. Under normal conditions, it is able to assemble a unified self-perception of the self from these representations,” researcher Giulio Rognini explained in a statement.
“But when the system malfunctions because of disease – or, in this case, a robot – this can sometimes create a second representation of one’s own body, which is no longer perceived as ‘me’ but as someone else, a ‘presence,’” he added.
The Ecole Polytechnique Fédérale de Lausanne researchers expect that their work showing how and why people sometimes report the presence of ghosts will help pave the way for a better understanding or more complex conditions such as schizophrenia.
To get a better idea of what this series of experiments entailed, check out the video below.
