'Ghostly presence' created in
lab
7
November 2014 By
Rebecca Morelle Science Correspondent, BBC News
Feelings of
a ghostly presence - the sense that someone is close-by when no-one
is there - lie in the mind, a study has concluded.
Scientists
say that they have identified the parts of the brain that are
responsible for generating these spooky sensations.
They have
also created an experiment that makes some people feel like there
is a ghost nearby.
The
research is published in the journal Current
Biology.
There are
many tales of the paranormal, but an often-reported phenomenon is
that of the invisible apparition.
Dr Giulio
Rognini, from the Swiss Federal Institute of Technology (EPFL),
says: "The sensation is very vivid. They feel somebody but they
cannot see it. It is always a felt presence."
He said it
was common in those who experience extreme conditions, such as
mountaineers and explorers, and people with some neurological
conditions, among others.
"What is
astonishing is that they frequently report that the movements they
are doing or the posture they are assuming at that specific moment
is replicated by the presence. So if the patient is sitting, they
feel the presence is sitting. If they are standing, the presence is
standing, and so on," he explained.
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
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'."
The
researchers said that their findings could help to better
understand neurological conditions such as
schizophrenia.