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Comment by gcthomas | Hacker News Reader

The 'placebo effect' seems to be wholly the effect of the sum of biases and psychological effects on reported outcomes in the placebo (non-treatment) arm of medical trials. It doesn't mean there is an 'actual' effect, it is just that reported benefits by patients is affected by the situation. 'The nice doctor gave you pills, and trying to be helpful you might respond more positively when asked if you are any better.' Or 'patients with a temporary flare up in their condition were invited onto a trial, and - lo - they got better even without the active treatment.'

Placebo just refers to the bundled biases and other uncontrolled-for influences. It is not a real thing that can be used to make anyone actually better. Whenever there is a physical measurement that can be made about some affected body function, the placebo effect mysteriously disappears.

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I don't know about that. There's also the nocebo effect [1] that is rather well known. You make it sound like "placebo" is purely a bias thing, but AFAIK both placebo & nocebo effects, though presumably psychogenic, can sometimes induce measurable changes in the body.

[1]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3401955/

Don't you think it is intriguing that the placebo effect only gets reported for non-specific subjective complaints, and not physically measurable ones?

This article lists a few physically measurable changes caused by placebo:

https://www.medicalnewstoday.com/articles/306437.php

WhyDontPlacebosRegrowLimbs.com

(Not a real site, just riffing off whydoesntgodhealamputees.com.)

There’s a great chapter in Thinking Fast and Slow where he talks about how placebo might be only a statistical phenomenon: regression to the mean. Sick people are a statistically extreme group, and tend to revert to the mean over time without intervention.

does that stand up to experiments pitting a placebo group against a control group that gets no treatment at all?

No, it does not. While Kahneman is a wonderful scientist (psychologist, btw), he has this annoying habit of attempting to fit everything into his models. He's dead wrong on placebo, even though regression to the mean is a real thing.

There is research supporting Kahneman: https://www.ncbi.nlm.nih.gov/pubmed/1280801

So while I don't dispute your link (because it's correct), the placebo effect is normally defined as the effect over and above that seen in the no-treatment group (who don't get a placebo or treatment). Regression to the mean would impact both placebo and no treatment (as well as treatment) groups equally, so cannot be the explanation for the entirity of the placebo effect.

Placebo patients know that they have received a treatment, so that introduces a bias in the reporting of outcomes from the patient, even if the medics are blinded. If you believe you have been treated it is well known that patients report improvements even for illnesses that can be measured not to have improved.

The breaking of blinding and contrary measurements is enough to undermine most claims for placebo.

Yes, I agree. That's what the no-treatment group controls for. And generally, both medics and patients are blinded.

I sometimes wonder about the validity of comparison with the placebo. What if the drug being studied makes the patients feel something, but doesn’t directly help the condition being studied. But that something feeling alerts the patients that they’re getting the real drug and not the placebo, and that awareness causes all the psychological biase we’re worried about?

Kahneman is supported by research. https://www.ncbi.nlm.nih.gov/pubmed/1280801

Good luck finding an ethics board who will let you do that experiment on actually sick people.

"Ah, people with pain. One group will get nothing and the other a placebo."

so do it with the common cold or something equally untreatable/fairly harmless.

not that I was proposing such a study - I was asking if we have already done them and what the data says if we have.

Pretty sure they do that all the time?

Reminds me of the old joke, where a respected scientist is announcing he has some great cure for the disease of the day and is presenting the impressive results to an audience, when someone pipes up and asks:

'How did this compare to the control group?'

The presenter is indignant and says, "Excuse me? You're asking if I randomly selected half of these poor souls to be deprived of the medicine, just to see what would happen to them?"

'...yes.'

"Of course not! That would have condemned half of them to an avoidable death!"

'...but which half?'

I love this. It's not even a joke really.

No, it cant be just that. We know for example that lack of social support causes increase in pro inflammatory cytokines, among other real effects. It would be highly implausible for the placebo effect to not be rral.

I don't see the distinction. If you think you feel better you do feel better, doesn't matter why. However, unlike some, I do not think this justifies the use of nonsense medical practices. You can be kind and caring to the patient and NOT sell them kinesio tape or wathever.

The fundamental question here is simple. To what extent can the mind affect the body? There can be no argument that the mind has at least some effect: a straightforward example is mood and blood pressure. For now, let's assume that this extent can be large.

Following is the assumption that, while we have learned a lot recently, the total map of mind/body connections is enormously larger than our current understanding of it.

So, it seems possible to me that the placebo effect can have real, physical and measurable effects on a human body, given the above assumptions.

One way or another, decades of research of, to varying degrees, confirmed this connection, though we haven't made much progress in understanding the underlying mechanisms of action.

I strongly believe that, "placebo" effect is probably just contextual effects. There is an experiment (I don't remember the name) with 4 cases:

- A placebo pills and a nice, empathic, optimistic doctor - No pills and a nice and empathic doctor - A placebo pills and a cold and pessimistic doctor - No pills and a cold and pessimistic doctor

The pills have practically no effect at all, doctor behavior can have a measurable impact.

Besides I don't think there is a proven effect of placebo for other than psychosomatic symptoms (in particular pain and depression symptoms).

I would take the time to closely read the article. It points to several cases where the placebo effect went beyond psychosomatic, specifically treating irritable bowel syndrome and preventing heart disease.

> Whenever there is a physical measurement that can be made about some affected body function, the placebo effect mysteriously disappears.

What matters is not that subjective feelings do improve?

The claim is that physical ailments improve, which isn't true if there are physical measurements takes.

Well apparently there are physical measurable effects, as another poster commented below.

https://www.medicalnewstoday.com/articles/306437.php

It depends what you have. I don't want to feel great if I still have terminal cancer. I want it cured.

With the exception of pain

I don't think pain can be measured reliably at all, nor can it be reliably communicated.

I suppose if you're a staunch Behaviourist you can say that

It's such a shame that the two scientific fields that we desperately need to advance, psychology and neuroscience, often need to rely on purely subjective input.

How would it ever be any different? You can't really remove subjectivity from the measurement of people and their brains.

One trick is to figure out if there are any objective measurements that can be taken which line up with the subjective input. One example is taking an EEG recording while performing a backward-masking experiment (aka displaying subliminal images), and seeing if their subjective experience "I did see the second image" versus "I did not see the second image" line up with the EEG measurements in the prefontal lobe.

https://www.amazon.com/Consciousness-Brain-Deciphering-Codes...

I'm not sure if we can actually localise particular EEG's that precisely. In any case, that just punts on the problem - subject reports they did or did not which we use to make an assessment. We still rely on subjectivity.

Like, I really don't see any way of avoiding this in psychology and neuroscience (and indeed even if possible, it might not be a good idea).

But we can localize it that precisely, and cheaply. In that particular experiment, they found that the areas of the brain that are commonly associated with raw visual input activates precisely whenever an image appears, subliminal or not. Then a large, delayed negative wave reliably appears in the frontal lobe only when the patient affirms that they saw the image. It's using objective methods to confirm the subjective.

These sorts of experiments are helping with making prognoses of whether a patient recovering from a coma will remain in a vegetative state, or if they'll regain consciousness in time.

Do you happen to have a paper link, rather than a book link?

Sure, I don't have the book on me, but this journal entry (written by the author) in Neuron outlines the main points raised here with plenty of references/citations to back it up. https://www.sciencedirect.com/science/article/pii/S089662731...

Just because we can only measure something subjectively right now doesn't mean that we won't be able to measure it objectively in the future, unless of course we don't bother trying.

How is it a shame that solvable problems are solved before unsolvable problems? The alternative would be NOT solving solvable problems.

Not sure how you construed that from my response, but regardless, I'd argue that tackling the "unsolvable" problems is still a worthwhile pursuit. The alternative would be not discovering germ theory or quantum mechanics (well, more relevant examples would be the realm of philosophy and psychotherapy).

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