A fascinating study has just been published by scientists working at the University of Pennsylvania. The methodology and results are described in this article, released last Friday, entitled "Neuroimaging During Trance State: A Contribution to the Study of Dissociation," but the gist is that that the team involved, headed by Julio Fernando Peres, has done PET (Positron Emission Tomography) scans of alleged mediums who claimed to be in touch with the spirits of the dead.
These particular mediums say that they can perform psychography, which is when the spirit of a deceased person is working through the medium's body, controlling his/her hand to produce written text. Now, neuroscientists understand fairly well what is happening in the brain when a person speaks or writes; in particular, when someone writes complex text, several areas of the brain (including the left culmen, left hippocampus, left inferior occipital gyrus, left
anterior cingulate, right superior temporal gyrus and right precentral
gyrus) show higher levels of activity. The researchers compared the mediums' levels of brain activity when producing text in the ordinary fashion (i.e., when they claimed they were not being guided by a spirit, and were fully conscious and fully themselves) and when they were in a trance state. And when they were in a trance state, all of them showed consistently lowered activity in all of the brain areas that are typically higher during writing. Peres et al. state, "The fact that subjects produced complex content in a trance dissociative
state suggests they were not merely relaxed, and relaxation seems an
unlikely explanation for the underactivation of brain areas specifically
related to the cognitive processing being carried out. This finding
deserves further investigation both in terms of replication and
It's an interesting finding. The response of psychics to this article thus far can be summed up as, "Ha. We told you." And indeed, this result is exactly what you'd suspect if what the mediums claim is true -- that their hand was no longer under the sole control of their own brains, that someone else had taken over and was guiding their motions.
I am, however, not convinced that this is the only explanation, and I was glad to see that the authors weren't quite so eager to jump on the bandwagon -- their final statement that "this finding deserves further investigation... in terms of... explanatory hypotheses" is precisely right. We cannot rule out that there is control by a spirit; that hypothesis is consistent with the results. But before saying that this constitutes proof of psychic mediumship, other possible explanations must be ruled out.
I have to say, though, that these folks are going about this research in exactly the right way. If psychic phenomena of any kind exist, they should be testable, verifiable, and replicable under controlled conditions. The fact that these alleged mediums are showing anomalous brain activity is certainly suggestive that something worth studying is going on here -- and I hope that Peres et al. or other researchers in the field will pick up this study and run with it. If the results hold, we may be looking at the first step toward hard evidence for the existence of a spiritual realm, which would be an absolutely stunning result (although I have to say that if this proves to be the case, the number of retractions I'd have to write for scoffing statements in previous Skeptophilia posts would be equally stunning). My overall reaction: while I'm still in the doubters camp regarding what this study means, at least we finally have some folks who are approaching the question scientifically. And that is a step in the right direction.