In 2006, a team of neurologists led by Shahar Arzy and Olaf Blanke reported on an unusual case of felt presence. A 22-year-old woman was having a pre-surgical evaluation for epilepsy treatment, and she had given consent to have her brain stimulated with electrical current. Among the sites stimulated was the left temporoparietal junction (TPJ), an area of the brain behind and above the ear where the back of the temporal lobe meets the lower side of the parietal lobe.
When the experimenters probed this area, a striking thing happened: a strong feeling of a shadow presence befell the woman, occurring directly behind where she was sitting. When they tried it again, she described “a ‘person’ as young and of indeterminate sex, a ‘shadow’ who did not speak or move, and whose position beneath her back was identical to her own.” They then tried stimulation while she was standing, then in a different sitting position: each time the presence mimicked her, and at one point — unpleasantly — she felt it embrace her. This shadow figure was not her, but its movements were inextricably tied to her own. What had produced this phantom?