In September
2006 it was reported in
Nature that Shahar Arzy and colleagues of the University Hospital,
Geneva, Switzerland, had unexpectedly reproduced an effect strongly reminiscent of the doppelgänger phenomenon via the
electromagnetic stimulation of a patient's brain. They applied focal electrical stimulation to a patient's
left temporoparietal junction while she lay flat on a bed. The patient immediately felt the presence of another person in her "extrapersonal space". Other than
epilepsy, for which the patient was being treated, she was psychologically fit.
The other person was described as young, of indeterminate sex, silent, motionless, and with a body posture identical to her own. The other person was located exactly behind her, almost touching and therefore within the bed that the patient was lying on.
A second electrical stimulation was applied with slightly more intensity, while the patient was sitting up with her arms folded. This time the patient felt the presence of a "man" who had his arms wrapped around her. She described the sensation as highly unpleasant and electrical stimulation was stopped.
Finally, when the patient was seated, electrical stimulation was applied while the patient was asked to perform language test with a set of
flash cards. On this occasion the patient reported the presence of a sitting person, displaced behind her and to the right. She said that the presence was attempting to interfere with the test: "He wants to take the card; he doesn’t want me to read." Again, the effect was disturbing and electrical stimulation was ceased.
Similar effects were found for different positions and postures when electrical stimulation exceeded 10
mA, at the left temporoparietal junction.
Arzy and his colleagues suggest that the left temporoparietal junction of the brain evokes the sensation of self image—body location, position, posture etc. When the left temporoparietal junction is disturbed, the sensation of self-attribution is broken and may be replaced by the sensation of a foreign presence or copy of oneself displaced nearby. This copy mirrors the real person's body posture, location and position. Arzy and his colleagues suggest that the phenomenon they created is seen in certain mental illnesses, such as
schizophrenia, particularly when accompanied by
paranoia, delusions of persecution and of alien control. Nevertheless, the effects reported are highly reminiscent of the doppelgänger phenomenon. Accordingly, some reports of doppelgängers may well be due to failure of the left temporoparietal junction.-
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