Why does the placebo effect work?

The placebo effect is a long-recognised phenomenon that has played an important part in the history of medicine -- from the healing powers of Stonehenge to administering placebo drugs to modern day patients. But it's not until recently that science has begun to truly understand how the placebo effect really works.

Professor Nicholas Humphrey asks why placebos work and reveals their central paradox: If we can effectively cure ourselves by taking placebo medicine, why don't we just heal ourselves straight away?

Exploring this paradox from the perspective of evolution, Professor Humphry looks at the associated costs and benefits of pain or illness. How can placebo medications readdress this balance and is a "dose of contrived optimism" just what the doctor ordered?

Find out more about Prof Nicholas Humphrey:

10 Unanswered Science Questions

This video is part of a series brought together by the All Times 10s YouTube Channel exploring ten unanswered science questions.

To view the greatest minds on YouTube respond, follow the link at the end of the video or click below:

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[Half_Centaur]

The most amazing thing about the placebo effect, to me, is that it works even when you know that you're taking a placebo. There have been several studies that showed patients improved from all sorts of ailments by taking what they knew were sugar pills when compared to a control group that was given no treatment. It's possible that just the ritual act of taking a pill can help trigger the effect. The human mind is an amazing and enigmatic thing.

[grammaton]

Not to mention the fact that a patient's own emotional state and expectations from his own illness directly affect his recovery, is a universally accepted medical truth.
In fact this was told to me by my grandfather, a world-renowned surgeon with over 60 years of experience.

[GreaterGood]

What amazes me is that in many cases of patients of Chronic diseases Allopathy drugs consistently induce the Nocebo effect as evidenced by the Spontaneous progression of the Chronic disease whereas Homeopathy medicines consistently induce the Placebo effect evidenced by the Spontaneous regression of the Chronic disease

[AnthonyScottGames]

I’ve been studying/trying to understand hypnosis for a long time. Changed my mind about it a few times. Recently I started thinking maybe it works in a similar way to the placebo effect. Your explanation is amazing. Many of the things the placebo can effect are the same that hypnosis (supposedly) effect. I think the most important thing for me to take away is that almost all results for both methods are short term, and don’t truly fix the problems. They seem to change your attitude to “ok, I don’t need to feel that pain right now because I’m safe”. I think a lot of people make the mistake of seeing short term relief of an ailment as proof of a cure. Thank you so much!

[alltimes]

Glad to see your channel is getting the recognition it deserves! :D

[Pumpkindemon]

How is it possible I never came across this channel with all the science video's I watch?

[Ontologistics]

This does not explain the placebo effect. It simply speculates as to why it happens from an evolutionary perspective (in a non-falsifiable way, I may add). The important question, however, is how a phenomenological state, a belief, can cause physiological change for the benefit of the organism.

[TheRoyalInstitution]

Hi, it's called 'Scwarz by The Jakesperiment' - we put music credits at the end of each film.

[InsectInYourEars]

I've always wondered about this, and I have tried to explain it to my friends but they think I'm just being stupid, but if I tell my self that the pain isn't real or that something doesn't actually hurt then I find that it actually goes away, it's not pain, it's just a sensation.

[ragnkja]

The amazing thing about this video is that it also explains why placebos work even when the person given the "medicine" knows it's a placebo: he or she subconsciously knows that if real medication was necessary, that'd be what the doctor would have prescribed.

[relaxingcat]

The placebo effect in my opinion is barely covered in this video. I saw and read about a doctor who told his patients that they were going to recieve the latest and best surgery on their knees to remove their osteoarthrits, but all the doctor did was just make cuts on the knee and nothing else and the patients that recieved the fake surgery all reported they felt completely healed. Also there was a dr. back in the early 20's i think, that healed a kids skin that was covered in warts  because he convinced the boy that the skin disease was actualy something a lot less serious. imo the placebo effecct could save millions of dollars a year.

[TheRoyalInstitution]

Great stuff! Delighted you enjoyed it.

[grass]

THIS IS WHY YOU DONT FEEL THE PAIN OF A CUT UNTIL YOU SEE IT. As in sometimes, you suddenly notice a cut or a bruise on your body and you don't remember when it happened and it suddenly starts hurting!

[GeneralTherd]

True, we did this in Iraq, people would ask our platoon medic for help and all we could do was give them an 800mg ibuprofen. They thought we were helping them. I think it may have something to do with getting rid of the stress, cortisone and adrenaline can cause long term health issues and suppresses the body's immune system. I also think it has something to do with the power of thought that has only recently been studied in science. In time we will learn more about how our world works.

[mishx]

but the best part about the placebo effect is the fact that it works on psychological problems as well, and unlike physical problems it's essentially costless, I think that fact is just so great.

I simply love the ways our brain works.

[SomeoneBeginingWithI]

When the boy's mother turns up, his wound doesn't suddenly heal. His injury is no better than it was before, but he feels better because his mother is there. Therefore his mother is (or administers) a placebo.
Many parents and carers of children do this consiously by 'kissing it better', and it works. This is a valuable use of placebo. The child is injured, they feel pain, which causes them to stay still and cry to atract the attention of an adult. If they were badly injured, they would have the best chances of surviving and recovering because they remained still so as not to cause further damage and got help as soon as possible. If they're not badly injured, the adult can administer a placebo and the child feels well again and can continue as before.

[OdysseyOfAman]

I have actually tried this thing called self healing. I just didnt know that we even had a name for it. Just saw this now & agree with it. It works ;-)

[berwynsigns]

Subbed at 3:59, then thought about it and wondered why I didn't subscribe before. Then I remembered I was paying attention to the very well-made, very high quality, interesting video. Nice job!

[ssuhuss]

This is probably the most civil and well mannered chain in YouTube, thank you both for restoring my faith in humanity and rendering the common notion that YouTube is only good for religious wars, moot.

[KitZunekaze]

I'm watching all 10 of these videos in the 10 unanswered questions, and I'm doing so in a sort of means to find informative science channels. My rule was that I would watch all 10, and go back afterward to subscribe to the ones I found the most informative or enlightening. This is the only one so far that I'm subscribing too before finishing the rest. I don't want to lose this one.