Trending science: Researchers explore that ghostly ‘feeling of presence’
Halloween may be behind us for another year but that doesn’t mean that the ghosts and ghouls have left the building! Researchers say they have discovered where the ‘feeling of a presence’ (FoP) often attributed to ghosts comes from, and they have built a robot that recreates that very same eerie sensation! Led by Olaf Blanke of Ecole Polytechnique Fédérale de Lausanne, the research team worked with 12 patients who had conditions such as epilepsy, stroke, migraine, and tumours, and had all reported feeling a presence nearby. They discovered that the FoP is an illusory ‘own-body perception’ that is associated with sensorimotor loss and caused by lesions in three distinct brain regions: temporoparietal, insular, and especially frontoparietal cortex. Different lesions have their own associated sensory and motor deficits. The research team suspect that the FoP sensation is caused by confusion over the source and identity of sensorimotor signals. As IFLScience notes, ‘People misattribute their own signals or bodily movements as something “other,” resulting in the ghostly sensation’. Blanke tells New Scientist, ‘You are convinced that there is something, but you don't see anything, you don't hear anything.’ Based on these data, the research team designed a master-slave robotic system that generated specific sensorimotor conflicts and enabled them to induce the FoP and related illusory own-body perceptions experimentally in different participants with no mental health problems. According to the study summary, published in Current Biology, ‘these data show that the illusion of feeling another person nearby is caused by misperceiving the source and identity of sensorimotor (tactile, proprioceptive, and motor) signals of one’s own body’. New Scientist elaborates on the master-slave robotic system: ‘The robot had two components: a master and a slave. The volunteers were blindfolded and asked to move an arm of the master robot with one hand. This caused the slave robot, behind them and touching their back, to move. In essence, they were able to make the slave robot stroke their own backs.’ According to New Scientist, five of 17 people spontaneously reported feeling a presence behind them – without even being asked about it. It is thought that the findings could one day help patients with schizophrenia. Research team member and robotics expert Giulio Rognini notes to New Scientist: ‘The same way that you can trick the brain into creating an alien presence, you could train the psychotic brain to relearn the difference between self and other. The dream would be to down-regulate psychosis. But we are far from that.’ For more information, please visit: http://www.cell.com/current-biology/abstract/S0960-9822%2814%2901212-3(opens in new window)
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