The Research Digest Blog had a posting (here) titled ‘A spontaneous experience of a sensed presence caught on EEG.

A patient who was being treated after a motor accident, had experiences of a presence when she was alone and happened to be having her EEG recorded when the episode happened.

“It began with a feeling of an electric shock in her right hand, was followed by her arms and hands feeling icy cold, then vibrations went through her body, before she experienced the feeling that a man was in the room with her, even though she was actually alone.
A look at the EEG scans showed that a burst of electrical activity, similar to that observed in an epileptic seizure, occurred in her left temporal lobe at approximately the same time that she reported the sensed presence on her right-hand side.
“Although over the last 20 years we have assessed hundreds of patients who reported the emergence of a sensed presence … this is the first time the reports of a strong ‘sensed presence’ and related sensations occurred ‘spontaneously’ while our screening electroencephalographic measurements were in progress,” said Persinger and his coauthor Sandra Tiller.”

 This seems to be another of those ‘fringe’ qualia (the ‘I am not alone’ feeling) that populate consciousness. We can only see that it is there when it is inappropriately there.