(2019-07-29, 04:59 PM)sbu Wrote: Some years ago there was weekly headlines in newspapers about all sorts of correlations between fMRI data and ‘subjectivity’. like this study: Brain Scans on Mormons Show Religion Has a Similar Effect to Taking Drugs Number of participants: 19I see. I thought you were specifically talking of the technology. It must be note how all of the misguided conclusions you quoted could be applied to parapsychologists using statistical analysis.
Thankfully a study by Eklund et al. kicked of a criticial debate about statistical methods in fMRI studies, which apparently is taken very serious by the ‘fMRI business’.
Abstract from Eklund et al.
Functional MRI (fMRI) is 25 years old, yet surprisingly its most common statistical methods have not been validated using real data. Here, we used resting-state fMRI data from 499 healthy controls to conduct 3 million task group analyses. Using this null data with different experimental designs, we estimate the incidence of significant results. In theory, we should find 5% false positives (for a significance threshold of 5%), but instead we found that the most common software packages for fMRI analysis (SPM, FSL, AFNI) can result in false-positive rates of up to 70%. These results question the validity of a number of fMRI studies and may have a large impact on the interpretation of weakly significant neuroimaging results.
In a follow-up study a year later another group writes:
The current discussion shows that the validity of fMRI data analysis paradigms has not been uniformly established and needs continued in-depth investigation. fMRI is a complex process that involves biophysics, neuroananatomy, neurophysiology, and statistics (experimental design, statistical modeling, and data analysis). fMRI data have a low signal-to-noise ratio (14, 15). As a consequence, all of the biophysics, neurophysiology, and neuroanatomy that underlie fMRI should be used to design experiments, formulate statistical models, and analyze the data to increase the signal-to-noise ratio and information extraction. Achieving more accurate fMRI data analyses is a challenging interdisciplinary task that requires concerted collaborations among physicists, statisticians, and neuroscientists who, together, can question the current approaches more deeply and construct more accurate analysis methods.
In an ideal fMRI statistical analysis, the relationships among the voxels would take account of the spatial and temporal properties of the experiment and the scanner thermal noise (16). The experiment’s spatial and temporal properties are dictated by the physiological changes (neural activity, blood flow, and blood oxygenation levels) induced by the particular behavioral task and background physiological activity and anatomy (white matter, gray matter, the ventricles, and blood vessels) of the relevant brain regions. The ideal fMRI acquisition scheme would be accompanied by a characterization of these spatial and temporal processes so that the subsequent data analysis can correctly take them into account (16). Improving fMRI statistical methods must combine research to decipher the meaning/origins of the blood oxygen level-dependent signal with characterizations of the spatiotemporal properties of task-related activity, background physiological activity, and scanner properties. Sharing data and methods would greatly expedite validation (9).https://www.ncbi.nlm.nih.gov/pmc/article...po=2.50000
My personal hunch is that on top of the 3500 studies invalidated due solely due to statistichal methods, several thousands more studies would be invalidated if someone actually tried to reproduce them as is the case in several other studies in the various sciences.
How to Survive a Lightning Strike
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(2019-07-24, 02:05 PM)Sciborg_S_Patel Wrote: How to Survive a Lightning StrikeI had a friend some years ago who survived a lightening strike. She became extremely psychic - seeing dead people, telepathic, seeing past lives etc. She said it took her years of training to turn it off or block it so she could resume normal functioning. At one point she had a lot of people interested in exploiting her abilities - Hollywood types wanting to sensationalize and market her. She rejected all that and went back to her career in the medical field. In spending time with her she would often sense things about me that bordered on uncanny but only things that might have been helpful. At any rate: One interesting thing she told me was that she attended a yearly meeting for survivors of electrocution either by lightening or contact with power lines and other man made electrical power sources. In getting to know these people she claimed that many of the lightening survivors had psychic openings similar to hers but were very reluctant to talk about them with anyone they didn't trust. On the other hand she said non of the people who were shocked by human made power sources mentioned any of the psychic openings claimed by the group struck by lightening. (2019-07-29, 06:11 PM)Larry Wrote: I had a friend some years ago who survived a lightening strike. She became extremely psychic - seeing dead people, telepathic, seeing past lives etc. She said it took her years of training to turn it off or block it so she could resume normal functioning. At one point she had a lot of people interested in exploiting her abilities - Hollywood types wanting to sensationalize and market her. She rejected all that and went back to her career in the medical field. In spending time with her she would often sense things about me that bordered on uncanny but only things that might have been helpful. At any rate: Transformed by Lightning: Real Life Stories by Louis Proud Quote:Thais’s encounter with lightning left her with few if any injuries. A couple of months after the incident, however, she noticed two strange aftereffects. First, she could no longer wear a watch without it “losing 10-20 minutes and becoming unreliable.”27 She adds: “At first I kept thinking I was buying watches that were too inexpensive. It took a couple [of] years to realise it wasn’t the watches but me that was the problem!”28 The second strange aftereffect is that her psychic abilities became heightened. She comments: “This [heightened psychic abilities] is not something I previously had interest in and definitely not something I was looking for. I have always been a very private person and didn’t want to know things about other people, but I found myself somehow knowing things about folks I didn’t know well.”29 Quote:There is a belief among the North American Indian tribes known collectively as the Sioux that when a person is struck by lightning or has visions featuring Wakinyah (“thunderbirds” or “thunder beings”) it can indicate they’ve been chosen to become a special type of medicine man called a Heyoka (“thunder dreamer.”) A Heyoka differs from a conventional medicine man in that he does everything in a contrary fashion. He is a sacred fool, whose clownish antics are a source of amusement to others. The powers with which Heyokas are gifted derive from the thunderbirds. A thunderbird is a spirit of lightning and thunder in the form of a huge Eagle-like bird. Lightning they produce from their beaks; thunder they produce through the beating of their wings. They are also responsible for the production of rain.
'Historically, we may regard materialism as a system of dogma set up to combat orthodox dogma...Accordingly we find that, as ancient orthodoxies disintegrate, materialism more and more gives way to scepticism.'
- Bertrand Russell |
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