« Online neuroscience tutorial | Main | First week shouts »

December 10, 2004

Ghosts in the machine:

Controversy has erupted over Michael Persinger's findings that applying weak complex magnetic fields over the temporal lobes can induce unusual experiences, particularly the experience 'sensing a presence' in the room, which Persinger has linked to religious belief and spiritual experience.

This work was part of a larger project in which Persinger and his colleagues have reported strong links between temporal lobe disturbance and anomalous beliefs and experiences throughout the population.

However, a group of Swedish neuroscientists led by Pehr Granqvist have reported that they've failed to replicate Persinger's results with magnetic stimulation when they used a double blind approach to running their experiments (where neither the experimentor nor the participant knows whether they are getting magnetic stimulation).

Persinger has replied by stating that the Swedish study was not an accurate replication.

Link to story on nature.com

—Vaughan.

Posted at December 10, 2004 08:49 AM

Comments

nick_name says:

Persinger had more to say than just that Granqvist didn't replicate his reasearch. Apparantly the Swedish researchers failed to calibrate their computer, which was running software calibrated for the 286 PC (20 mhz or so). It's a DOS software that has significant distortions in the output when run under windows. Granqvist reported a lack of 'sensed presence' experiences, but his procedures weren't the same as the ones that produce it in 80% of the population.

Persinger uses a large acoustic chamber for his research. Granqvist used a 1.4 x 1.4 meter cube (quite small by comparison) for his.

In contrast to the claim made by Granqvist, Persinger uses double-blind protocols. Here are a few sample papers where they were not only followed, but described in the paper:

M. A. Persinger, Increased emergence of alpha activity over the left but not the right temporal lobe within a dark acoustic chamber: differential response to the left but not the right hemisphere to transcerebral magnetic fields. Int. J. Psychophysiol. 34 (1999) 163-169.

M. A. Persinger, The sensed presence within experimental settings: implications for the male and female concept of self. J. Psychol. 137 (2003) 5-16.

M. A. Persinger, F. Healey, Experimental facilitation of the sensed presence: possible intercalation between the hemispheres induced by complex magnetic fields. J. Nervous Mental Dis. 190 (2002) 533-541.

Granqvist used 15 minute exposures to the signals, and these are just not long enough to have any significant effects for all but a very few people.

For more information:

http://tinyurl.com/6uodl

-and-

http://laurentian.ca/neurosci/News/Dec_news.htm

The second link is to Persinger's own response to Granqvist


Comment posted at December 16, 2004 04:43 AM

Post a comment

Thanks for signing in, . Now you can comment. (sign out)

(If you haven't left a comment here before, you may need to be approved by the site owner before your comment will appear. Until then, it won't appear on the entry. Thanks for waiting.)


Remember me?