The field changed caused by rotating in the Earth’s magnetic field is ~0.00005/1 (50 microTesla/1 second). The fields of concern from electric power lines are on the order of microTesla/s with the positive findings of leukemia in the vicinity of power lines occurring at 0.4 microTesla. There is no known or plausible mechanism for 0.4 microTesla to have biological effects.

Aluminum foil would partially shield the time varying magnetic fields used in TMS. But the currents induced by the field would cause the aluminum foil to melt or vaporize.

But from a more rational perspective, I have to wonder how much
of this study is akin to other studies which got blown out of proportion, particularly by the popular media, who only want the sensationaliz-able portions. “Magnets can change morals!” cries the headline-writer.

My point is- It seems from what I’ve been able to read that the authors are drawing conclusions about how people make moral choices. These conclusions may or may not be valid, but they cannot be based on a ‘significant statistical’ result from the experiment they describe.

1) The sample they tested is not representative of the population they are drawing conclusions about. (I doubt that the people being tested are a valid sampling of MIT sophomores, much less humanity). No-no.

2) Even if we imagine that the people being tested are representative of the whole, the sample size is too small to be meaningful.

It seems they are using the term ‘statistically significant result’ to justify the conclusions being drawn. This might be an error on my part, but it is clear the result they got has no statistical significance with the overall population of humans.

Oh, we probably agree here…

cheers

I wouldn’t go as far as saying there is any king of statistical “abuse” or misrepresentation in the paper. Quite the contrary, I think it’s reasonably well done and their methodology is rigorous as far as one can judge given the length of the paper (the proceedings usually don’t go into much methodological detail due to paper length restrictions)

The results are statistically significant in both experiments (p<0,05)

the things I'd pick on are:
- low subject number
- inconsistent TMS effects
- small effect

however because they performed two separate experiments (on two different groups of people) that basically had the same result their conclusions have more credibility.

In spite of that this kind of psycho-physiological investigation requires many more participants to average out the inherent inter-subject variability. This could all just be a fluke. If you look at their graphs you can get a better feel for the huge variability involved.

If they had done the same experiments with say 30 or 40 people, I'd be much more impressed and would probably feel their conclusion of the RTPJ controlling "empathy" (in these kinds of moral dilemmas) as reasonably well established.

One wonders why only 8/12 subjects were included given the fact that these were all young healthy volunteers. Such low subject numbers are not uncommon in neurophysiology research but usually one only sees this when dealing with some rare disease that makes it really difficult to gather up your experimental group.

My guess is that the limiting factor were their fMRIs which were done for each participant. These can get expensive and especially time consuming if (as is usually the case) one has to "beg" for research time on the MRI machine or work around a busy clinical schedule.

JurijD- I haven’t seen the original research report- (not currently available to me)-
Are there really claims of ‘statistical significance?’

This would be an example of the type of abuse that was pointed out in the recent article by Tom Siegfried and commented on here earlier.

you are of course quite right. whenever we poke around in the body there is the real possibility that our actions will do harm. And what TMS does is to magnetically induce eddy electrical currents in brain tissue that basically “stun” neurons thus obstructing normal function.

In essence it’s like throwing a wrench into a certain machine section and looking for what stops working when you “disrupt” that particular part.

Curious (at least to me when I first started dealing with it) is the fact that there do not seem to be any serious side effects to the procedure (if you exclude people who might get a seizure or are taking psychiatric medication).

I do still hold the belief that the procedure is quite new and that we would be well advised to firmly err on the side of caution when dealing with TMS. The medical profession has enough blunders in its past already and for a lot of them the contemporary view was that “the procedure was not harmful”, only for that to be later shown as quite uninformed (even for the time).