Ghosts or guardian angels are usually felt as a presence rather than seen as physical apparitions.
Researchers, reporting in the journal Current Biology, think they know where that feeling of the presence phenomenon comes from based on studies of 12 patients with various neurological conditions.
The scientists also devised a robot capable of giving otherwise healthy people the same feeling, simply by sending mixed-up signals to the brain.
“In our first experiment (with the robot), 30% of the healthy participants spontaneously reported the feeling of having somebody behind them, touching them,” says Olaf Blanke of Ecole Polytechnique Fédérale de Lausanne.
“Such spontaneous reports are quite unusual in the field of bodily illusions.”
The robot-induced feeling was so disconcerting for two of the healthy study participants that they
wanted to stop the experiment.
The patients the researchers studied perceive those invisible presences for periods of seconds to minutes as a result of a number of underlying conditions, including epilepsy, stroke, migraine, and tumours.
Blanke and his colleagues traced those frequent misperceptions of a being which isn’t there to damage in brain regions.
But many healthy people also experience the presence in a variety of situations.
The researchers built a robot which allowed them to apply sensory signal conflicts.
The robot made the participants of the study feel as though they were reaching out in front of them and touching their own backs.
When the robotic stimulation was asynchronous with the individual’s own body movements, something remarkable happened: people felt, in some cases very strongly, as though there were another person standing behind them, touching them.
Those individuals also felt as though their bodies drifted backward in space, toward this mysterious, other presence, and judged that there were more people in the room.
The findings explain an experience which has influenced mystical thought, fiction, and humanity itself, and it may shed light on schizophrenic hallucinations as well.
Watch the ghost at work:
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