In some sense, the debate of whether a subliminal programme works or not, must be won before the programme is followed. As the treatment by its very nature is hidden from the listener, marketing has a lot do to with how effective it is.
The question is often asked:
“It’s all just placebo isn’t it? If so, it works anyway, as long as I think it does.”
This question is also asked of religion, homeopathy and most notably Western medicine.
The placebo effect however is not universally accepted, and its very existence is controversial. Hróbjartsson and Gøtzsche (2001) conducted a series of meta-analyses on hundreds and hundreds of clinical trials. Here many studies were looked at under the same conditions, and evaluated on a common yardstick. While these studies are controversial and dispute a host of other studies, the authors have revisited their analyses a number of times, and gained much credibility and respect. They concluded that the placebo effect was only found in studies which relied on the patients’ subjective evaluation. That is to say, in pain studies, where reporting bias could be in play. Patients are typically polite to their doctors.
This finding was later countered by a 2005 study at the University of Michigan. The experiment using brain imaging PET scans severed the link between placebo and patients subject reporting. The PET scans measured the level of endorphin in hypothalamus following a saline injection into the jaw. Endorphins increased in the brain although the test subjects themselves had no reason to report less pain (Benedetti, Mayberg, Wager, Stohler & Zubieta, 2005).
In some situations it is also possible to show the treatment working separately from the placebo effect. Again, using PET scans, a significant overlap between placebo and test subjects was found (however the placebo effect cannot be statistically parsed from the actual treatment.) Nonetheless, those receiving the antidepressant showed additional changes in subcortical regions compared with those in the placebo group (Mayberg, Silva, Brannan, Tekell, Mahurin, McGinnis & Jerabek, 2002). This study went a long way to vindicate the use of antidepressants, however brought the field no closer to understanding the placebo effect.
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