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lunedì 7 marzo 2011

Virtual-reality avatars to create 'out-of-body' experience

Nel film Avatar, gli esploratori del pianeta Pandora trasmettono le loro menti in corpi alternativi. Alcuni scienziati del Brain Mind Institute all’Ecole Polytechnique Fédérale di Losanna in Svizzera hanno proiettato dei volontari in avatar digitali in grado di muoversi in un ambiente virtuale. La ricerca mira a comprendere come il cervello integra le informazioni provenienti dai sensi in modo da determinare la posizione del corpo nello spazio ma i risultati potranno essere usati per i videogiochi di prossima generazione o per il teletrasporto digitale.

Olaf Blanke, un neurologo che ha condotto il lavoro, ha utilizzato un sistema di realtà virtuale con delle videocamere collegate ad un video display montato sulla testa dei partecipanti. In precedenza gli stessi ricercatori avevano già provato a ricreare una sorta di esperienza “out-of-body” che può accadere realmente quando il cervello subisce dei danni dovuti a incidenti, epilessia o abuso di droga. I casi più comuni accadono per via di eventi traumatici come incidenti d’auto o durante operazioni.

In those experiments, carried out by Blanke and colleagues in 2007, volunteers wore goggles containing a video screen for each eye fed fed by a pair of cameras behind the participant. Because the two images were combined by the brain into a single image, they saw a 3D image of their own back. Experimenters then moved a plastic rod towards a location just below the cameras, in their field of view, while the participant's real chest was simultaneously touched in the corresponding position. The participants reported feeling that they were located where the cameras had been placed, watching a body in front of them that belonged to someone else.

In his latest work, Blanke's volunteers used a similar VR set-up and then wandered through different digital 3D environments while researchers physically touched them either in sync or out of sync with the digital humans, to see where the volunteers thought their bodies were in the virtual space.
He also "projected" male volunteers into female avatars and placed volunteers directly into their avatars, so they were no longer watching from behind. Blanke reported that, even when moving in a virtual scene, volunteers felt as if whatever happened to the avatar happened to them.
"They start thinking that the avatar was their own body," said Blanke. "We created a partial out-of-body experience. We were able to disassociate touch and vision and make people think that their body was two metres in front of them."
The volunteers all wore skullcaps, which contained electrodes, to monitor the electrical activity in the brain. The data recorded by these showed a heightened response in the temporo-parietal and frontal regions of the volunteer's brains, compared to control conditions. These parts are responsible for integrating touch and vision into a coherent perception.
Blanke said the work on inducing these experiences artificially proved that they were nothing more than a brain malfunction. "Instead of it being a spiritual thing, it is the brain being confused," he said. "Why do we think that it is spiritual when we don't think a phantom limb when one is lost is an example of the paranormal?"


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