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Full Version: Rubber hand illusions shed new light on our bodily sense of self
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EXCERPTS: We don’t experience the world purely in our minds, but as ‘embodied agents’, says Roy Salomon, a cognitive neuroscientist at the University of Haifa in Israel. Your sense of self is as connected to your limbs and guts as to the thoughts racing in your mind.

‘If we want to get a handle on the sense of self and consciousness, the first thing we have to try to understand is: how do we get this feeling, this illusion that the brain builds up, that we exist as a body in the world?’ Salomon says.

One approach researchers are using is to investigate what’s going on when the bodily sense of self is disrupted. In a recent paper in Nature Scientific Reports, Salomon and his colleagues examined how having experienced altered states in the past might change how a person regards their bodily self, whether those states arose via psychedelic drug trips or from psychosis, a condition where people have hallucinations and delusions that often affect their sense of self.

In these delusions, people can feel disconnected from a stable sense of self: for instance, believing that their bodies are being controlled by others, or that they can exert power over what’s going on around them. They might hear voices inside their heads that seem separate from themselves, or that belong to someone else.

The sense of self can also be affected dramatically, albeit transiently, by taking psychedelic drugs, such as psilocybin, LSD or DMT. People describe the feeling of leaving their bodies, merging with other people, other beings or the universe.

In the study, researchers gave participants ‘the rubber hand illusion’, which causes the strange sensation that a fake hand belongs to you...

[...] For the new study, a group with a history of psychosis, a group with past psychedelic experience, and a control group each underwent the static rubber hand illusion, and versions of the moving rubber hand illusion where the movement did or didn’t match up with their real hand. Everyone felt a sense of body ownership over the rubber hand during the basic illusion.

But in the moving illusion, the psychosis group had less of a sense of agency over the fake hand than the other participants: they didn’t feel like they were controlling the fake hand, and they didn’t feel it belonged to them. ‘Even when the psychosis patients were controlling the finger, they didn’t feel so much that they had control,’ Salomon says.

The findings can help us better understand what breaks down in psychotic disorders, at least when it comes to the bodily self... (MORE - missing details)