Joshua Krisch flags new research into the neurological basis of a ghostly presence:
Feeling of Presence, or FoP, is the disconcerting notion that someone else is hovering nearby, walking alongside you or even touching you. It’s the stuff of ghost stories, but also a real symptom of several neurologic conditions, including schizophrenia and Alzheimer’s disease. Scientists know so little about the underlying causes of FoP that long-term treatments and cures remain illusive.
Now, researchers are chipping away at the neurobiology behind that uncanny feeling. In a paper published November 6 in Current Biology, a team of scientists described how they used a custom-built robot to induce an eerie Feeling of Presence in healthy participants. Their findings confirm that sensorimotor conflict, a neurologic imbalance between what the mind perceives and what the body feels, lies at the root of some FoP illusions.
Rebecca Morelle discusses the study’s methodology:
To investigate, the researchers scanned the brains of 12 people with neurological disorders, who had reported experiencing a ghostly presence. They found that all of these patients had some kind of damage in the parts of the brain associated with self-awareness, movement and the body’s position in space.
In further tests, the scientists turned to 48 healthy volunteers, who had not previously experienced the paranormal, and devised an experiment to alter the neural signals in these regions of the brain. They blindfolded the participants, and asked them to manipulate a robot with their hands. As they did this, another robot traced these exact movements on the volunteers’ backs. When the movements at the front and back of the volunteer’s body took place at exactly the same time, they reported nothing strange. But when there was a delay between the timing of the movements, one third of the participants reported feeling that there was a ghostly presence in the room, and some reported feeling up to four apparitions were there. Two of the participants found the sensation so strange, they asked for the experiments to stop.
The robot is demonstrated in the above video. Morelle adds:
The researchers say that these strange interactions with the robot are temporarily changing brain function in the regions associated with self-awareness and perception of the body’s position. The team believes when people sense a ghostly presence, the brain is getting confused: it’s miscalculating the body’s position and identifying it as belonging to someone else. Dr Rognini said: “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. 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.'”
Julie Beck notes, “Aside from just being cool and spooky, this study could have real implications for how science understands schizophrenia”:
It’s possible that the signal confusion Rognini describes could account for some symptoms schizophrenia patients experience—like feeling as though they’re being controlled by an alien presence, for example. That’s why the researchers’ next steps are to get schizophrenia patients to try out the robot, and see if the effect it produces feels similar to their symptoms.
It also reveals something interesting about consciousness in general – that it’s not necessarily a given that our brains always understand what our bodies are doing, or even that they’re our bodies. “The brain has multiple representations of the body,” Rognini says, “and these are usually integrated together and give us a unitary experience of the body and self in space and time. We show that when there is some damage to the brain or some trick played by a robot, a second representation of our body arises in a way that gets perceived by us but not as our body but as the presence of another human being. Physically this presence is already hidden inside our minds.”