Dec 23 2008

Who Goes There?

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Have you ever had the sense that you were not alone, that another person, perhaps menacing, was in the room with you? And yet, when you look around, no one was there? This is a common experience, which researchers call a “sensed presence.” Neuroscientists hypothesize that this common experience likely has a neurological correlate – meaning that activity in some specific part of the brain is responsible for generating the sensation of a presence.

So far, research has validated that hypothesis. And recently the research team of Michael Persinger had the fortune of capturing a sensed presence event on EEG (which measures the electrical activity of the brain).

The subject is a woman who has had numerous episodes of sensed presence after a head injury. Persinger now presents a case report of her EEG, recorded while she experienced the sense of a man in the room with her when none was present. For some reason as yet unknown, 90% of time a sensed presence is of a member of the opposite sex. The EEG shows a burst of electrical activity in her left temporal lobe during the event, and of note she perceived the presence to be on her right side.  (Brain activity corresponds to the contralateral or opposite side of the world.)

This confirms prior evidence. Persinger previously published evidence showing that the incidence of a sensed presence could be manipulated in subjects by using transcranial magnetic stimuation. When applied to both temporal lobe or the right temporal lobe the incidence was greater than when applied to only the left temporal lobe or when a sham stimulation was done as a control. He postulates that perhaps a sensed presence occurs when there is a glitch in the communication between the two temporal lobes.

Persinger with another researcher, Tiller, showed that induced sensed presences tend to occur opposite the side of the brain being stimulated, as with the subject in this recent case report.

Persinger and another lead author, Cook, were able to induce the experience of a sensed presence in 9 of 15 volunteers in another experiment using magnetic stimulation. Of interest, one of the subjects had a history of “psychicaly” reading medical diagnoses from photographs. They reported that they would get flashes of visions in their left upper visual field. Cook and Persinger document that they were able to increase the frequency of these experiences by applying the magnetic stimulation in a blinded fashion. They also document that when a subject tries to look at or focus on the location of the presence it moves or evades their gaze.

This line of research has significant implications for anyone interested in the paranormal or mystical experiences. The experience of sensing a presence that is not physically there often triggers mystical interpretations – as is likely what happened with the “psychic” subject in the previous study. Often times the presence is given divine significance. Most people assume that whatever they experience is real (especially if are not intoxicated or if there is no other simple explanation at hand). They therefore will make sense of their experiences within their belief systems or world view. We see this happen also with the phenomenon of hypnagogic hallucinations (waking dreams), which in the past have been interpreted as demonic visitations but recently are more likely to be seen as alien abductions.

Persinger also showed that low level magnetic fields may induce the experience of a sensed presence. He postulates that geological activity, which can generate these low level magnetic field, may be responsible for mass hallucinations in areas with a lot of activity. Or at least increase the incidence of experiencing a sensed presence.

The understanding that our brains are electrochemical machines, albeit highly complex ones, liberates us from grasping at mystical explanations for brain-derived experiences.

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