David speaks with David Robson, an award-winning science writer specialising in the extremes of the human brain, body, and behaviour. He has previously worked as a features editor at New Scientist and as a senior journalist at the BBC. He is the author of The Intelligence Trap, which has been translated into fifteen languages, The Expectation Effect, and The Laws of Connection.

They talked about:

🧠 The stereotypes and misconceptions of intelligence

🧬 Genetic and environmental influences on intelligence

💡 The expectation effect

💊 The science behind placebos

💪 How powerful our minds can be

🚫 The limits of the expectation effect

This is just one part of a longer conversation, and it's the second part. You can listen to the earlier episode here:

Part 1: 🎙️ Science, Reasoning, and The Intelligence Trap with David Robson (Episode 97)

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📄 Show notes:

[00:00] Introduction

[02:05] Street interviews on knowledge and IQ

[04:04] The stereotypes of intelligence and education

[05:56] Misconceptions about intelligence and race

[08:13] The interplay of genetics and environment on intelligence

[11:16] IQ is more than just genes

[12:33] Reflection on school transition and career choices

[14:15] Unconscious influence of social norms

[14:58] What is the expectation effect?

[16:48] A positive view of ageing can lead to longer life

[19:18] Understanding placebo effects

[21:47] The psychology of pain

[23:21] The importance of psychological support in medicine

[25:56] How powerful the brain is

[28:47] Understanding the mind-body connection

[31:00] The expectation effect has limitations

[33:47] The brain is a predictive machine

[35:59] Is the brain capable of changing our physiology?

[37:43] The brain's role in physical reactions

[39:35] How enjoyment affects nutrient absorption

[41:43] The pygmalion effect

[42:39] The influence of teacher expectations

🗣 Mentioned in the show:

Garret Jones | https://theknowledge.io/garettjones-1/

Hive Mind | https://amzn.to/4bM6T0f

How the Potato Changed the World | https://www.smithsonianmag.com/history/how-the-potato-changed-the-world-108470605/

Charles C. Mann | https://theknowledge.io/charlescmann/

The Expectation Effect | https://amzn.to/4dq8Ukh

Placebo effect | https://theknowledge.io/mind-over-matter/

French paradox | https://en.wikipedia.org/wiki/French_paradox

Cholecystokinin | https://en.wikipedia.org/wiki/Cholecystokinin

Ghrelin | https://en.wikipedia.org/wiki/Ghrelin

Lisa Feldman Barrett | https://lisafeldmanbarrett.com/

The Predictive Brain | https://www.edge.org/response-detail/26707

Mind and Body Lab - Stanford University | https://mbl.stanford.edu/

Alia Crum | https://en.wikipedia.org/wiki/Alia_Crum

Pygmalion Effect | https://theknowledge.io/pygmalion-effect

Full episode transcript below

👤Connect with David:

Twitter: https://twitter.com/d_a_robson

Website: https://davidrobson.me/


The Intelligence Trap | https://amzn.to/4aWELqZ

The Expectation Effect | https://amzn.to/4bkisve

👨🏾‍💻 About David Elikwu:

David Elikwu FRSA is a serial entrepreneur, strategist, and writer. David is the founder of The Knowledge, a platform helping people think deeper and work smarter.

🐣 Twitter: @Delikwu / @itstheknowledge

🌐 Website: https://www.davidelikwu.com

📽️ Youtube: https://www.youtube.com/davidelikwu

📸 Instagram: https://www.instagram.com/delikwu/

🕺 TikTok: https://www.tiktok.com/@delikwu

🎙️ Podcast: http://plnk.to/theknowledge

📖 Free Book: https://pro.theknowledge.io/frames

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📜Full transcript:



David Robson: We're often not even aware of the expectations that we're carrying because we just assume that they're objectively true. But actually that's not the case at all, with lots of our beliefs, there might be a small part that's objectively true, but then there's also we kind of load that with subjective beliefs too. And just by altering that mindset, we can often turn the expectation effect to our advantage so we can have better health, better well-being, and even live longer.

This week I'm sharing the second part of my conversation with David Robson, who is an award-winning science writer specializing in the extremes of the human brain, body, and behaviour.

Previously worked as a features editor at the New Scientist and as a senior journalist at the BBC. He's the author of three books, The Intelligence Trap, The Expectation Effect, and The Laws of Connections, which is releasing in June of 2024.

So in this part, you're going to hear a bit of a conversation about intelligence and [00:01:00] the stereotypes and misconceptions that come along with it. Then we talk about the genetic and environmental impacts on intelligence.

And then we started talking more about his second book, The Expectation Effect, which was incredibly interesting. I love this conversation. There's so much that I have personally been interested in and done a lot of research on, on my own. And it was great to actually speak with a science writer who spent a lot of time sharing this information.

So you're going to hear us talking about the expectation effect and what that is. We talk about the science behind placebos and nocebos. We talk about the power of our minds and the limits of the expectation effect.

So you can get the full show notes, the transcripts and read my newsletter at theknowledge.io and you can find David online on Twitter @d_a_robson, we'll have the link in the description or the show notes. You can also find him on LinkedIn and Instagram. His website is davidrobson.me and we'll have links to all his books in the description.

Now, if you love this episode, please do share it with a friend, and don't forget [00:02:00] to leave a review wherever you listen to podcasts because it helps us a ton to find other listeners just like you.

Street interviews on knowledge and IQ

David Elikwu: Intelligence can really affect our lives in some ways or in some areas and in some domains and then in other areas either can even hamper us or doesn't seem to affect us at all.

Like one thing that came to mind recently, which is actually on the other side of the spectrum. I don't know if you've seen any of these videos where people will go up to someone on the street and they have a microphone and they'll ask a few people different questions. And I've seen loads of different versions of this one, where they ask them about geography, they asked them about countries around the world. There was one I saw recently, but they will ask people just to do basic maths and just sums in their head. And it's so interesting that, there's loads of people that just fail these tests. And, and these are just, it's a random sample because it's just whoever's walking down the street. It could be somewhere in New York, it could be somewhere in London. And it's astounding that, okay, on one hand, people don't know some basic geography. They don't know some basic maths, but then [00:03:00] simultaneously, until someone asked that question, you would never have known. This is an ordinary person that you bump into on the street every day. These are the people that are all around us.

And I mean, it comes up in, in politics. And one of the things that I like to, you know, have to remind myself of sometimes is that by definition, half of the people are below average IQ in, in a sense. But obviously when we make some of these decisions, everyone gets a vote. And so, there's going to be a wide spectrum of what people decide to do or the decisions that people make.

And actually that just reminds me of, I had Garrett Jones on, on the podcast a while ago, and he also has written a book that's about Intelligence and IQ. And we were talking about some of that and there's this idea. And I think you've talked about this as well, that people have, which is the, oh, there are, you know, different races have different levels of intelligence and some races are smarter than other races.

But then simultaneously, if you look at the data, there is just as much variance perhaps between let's say different racial groups as there is between the races themselves. And so actually, then it kind of, it doesn't really matter because the man [00:04:00] on the street, the average person that you bump into, there's just as much variance between any given race as there might be between any of the other races.

The stereotypes of intelligence and education

David Elikwu: And so again, it calls into question or what it makes me think. And I wonder what your thought is on this is that, how much does it actually matter? And we touched on it a little bit at the beginning, but if the average person on the street might not have a great grasp of geography, they might not have a great grasp of maths. I think I read earlier today that the average American has a reading level of about age 12. All of these things are true and that's the society that we live in.

But I think simultaneously, I don't know if it's because in the media, most of those people are college-level educated and the people that write in the magazines and that write the books and stuff that we read, it's almost like the perception of where everyone should be at is perhaps a bit higher than where everyone really is at, at least on average.

David Robson: Yeah, I think you're totally right about that. You know, and I think we actually I think this is true for so many different things to say like poverty as well I think [00:05:00] like, you know in the media, for example, you've got people who probably came from quite privileged backgrounds and they know theoretically there are people who didn't have those advantages. But they really struggle unless they go out looking for it, they really struggle to appreciate, you know what the differences might be and how big the spectrum is.

And I think it's the same you know, we have intelligence and education. I think people don't necessarily understand you know, just how wide the spectrum can be. Coming from you know, a working-class background say I find it a bit frustrating actually in the media that I think often then there can be this kind of people can make quite patronizing assumptions too. So it could be that people like assume that if you're, you know, you're not highly educated that you're also not at all intellectually curious, and I think that's quite unfair, you know, you might struggle with some high school maths or, literacy or whatever, but doesn't mean that you're also not kind of hungry for ideas too, or interested and willing to learn, you just might not have had the [00:06:00] advantages.

Misconceptions about intelligence and race

David Robson: So yeah, I think we, it's really difficult. I think it's just a perpetual problem with human beings of any area, is we're really difficult. We find it very difficult to put ourselves in other people's shoes and we make these kind of gross assumptions.

To come back to the question, like I do think education matters and you know, we should be giving everyone this kind of, we should be leveling the playing field, I think, to try to bring people up to like, as high standard as possible because there are advantages, obviously, not just for people's careers or for living their lives, actually, like, it can be really enriching to be able to you know, to read a newspaper and understand the statistics, if you haven't had a sufficient education to be able to read a news story and understand what the facts are telling you, I think that does put you at a disadvantage.

And I see it with my parents who are not very well educated, that they actually, and you know, struggle a bit, especially with like digital literacy, for example, or talking to a doctor and understanding kind of what the doctor's telling them about the [00:07:00] potential diagnosis like, they find it very confusing. And so they start to see that the kind of world is in opposition to them a bit, especially like these institutions. They feel quite isolated as if there's this kind of two-tier system and they're not part of it. And it's not something, because I had a better education than them, it's not something I experienced. So I feel much, that are able to go and get the support I need from a doctor, say, compared to my parents do. So yeah, I do think these things matter.

You know, if we're looking at the kind of genetics of intelligence and these ideas that, like you were saying that different races have different average level of intelligence or that different genders have different types of intelligence, all of that. I just don't think we're really taking into account all of the substantial social forces that might be producing these illusory correlations. Like, I don't believe that they're really big, or I don't think there are any significant IQ differences between races and I'm going to probably get, you know, there's going to be some races who will get quite nasty. They always do when people say this, but I [00:08:00] just think it's just seems so fundamentally unscientific to make that claim.

Yeah, so that's what I think, you know, differences between individuals, we can always try to like bring everyone to the highest level they're capable of by kind of trying to address basic things like health and education.

The interplay of genetics and environment on intelligence

David Elikwu: One thing that I find very interesting about the question of intelligence is that definitely a tremendous amount is genetic, but there's also the aspects of it that's environmental. And environmental on two levels, one within the lifetime of an individual. So there are plenty of studies where, okay, you look at like, let's say adopted children and you look at, okay, one child that's adopted into a family that has this economic background versus a child that's adopted into that economic background. And you see there's a difference in their future earnings or their career progression, et cetera.

There's also studies where you can look at one that I found really interesting, I don't remember all the details, but it was in the U.S. And I actually imagine you could probably do the same thing in the UK where, because [00:09:00] of how some county lines are drawn, you could have people that live in the same area but have to go to different schools. And one school might be in a, a district that is gets a lot more funding and the other school might be in a district that doesn't get much funding, but those kids both live in the same area, but if you're on this side of the street or in this side of the neighborhood, you're not in the cashman area for this type of school, you're in the cashman area for that type of school.

And you can see these remarkable differences in the lifetime earnings of these people simply because even though their backgrounds were actually the same, the people that they went to school with, that's like now, not even in their immediate family. Because they went to school with a different type of person, then their lifetime outcomes are dramatically different.

And so there's all these types of things, and that's like within your personal lifetime, and then you also have the environmental factors that are at scale as well. And I think that probably plays a tremendous factor. I spoke with Charles Mann, who's also a science journalist, and he's done a lot of really interesting work around I guess some of the [00:10:00] environmental factors, not specifically as regards intelligence, but just, you know, history and the environment, et cetera. And one thing that I found really interesting reading his work is some of these ideas that simply because there were Europeans that settled in a particular area that had potatoes, the potato pretty much changed all of Europe actually in terms of what is possible to build. Like, so, when you think about how many IQ points come from the potato being available in a particular area, the same if you look at China, a big part of central China, there isn't water. There isn't water there. And so what impact does that have then on, on people's IQ and their development over time? And then you think about pollution, you think about things like that.

I think it was also in China, there was a study of people that lived in a particular area where I think the area had been split into two for some reason, and there was some kind of factory plant that was on one side of this town or this village. And so all the people that are essentially in the blast radius of this factory, their IQs get lower and all kinds of stuff happens, not just to them, but also to their [00:11:00] children. Even once the factory is closed, their children still grow up with lower IQs, whereas people, within the same area, but just slightly further away from where this factory was, suddenly they are flourishing a little bit more.

And so again, it's this idea that these things aren't as static as we might like to assume, and you can't always extrapolate that information as much as you would like to as well.

IQ is more than just genes

David Robson: No, exactly. And you know, childhood health, like this, the sheer number of infections you have as a child, you know, that's drawing resources, fighting the infections is drawing resources away from your brain's development. So it's a very basic factor that's influencing IQs and could have, you know, could create some kind of observed difference between one area and another, in much the same way as the things that you're talking about.

And we can't always account for all of those, you know, when we're comparing different people. And so yeah, genetics your parents genes do affect your IQ to a certain extent, but you know, it's not, it's not the only factor at all. And there's even [00:12:00] you compared to your siblings, there's going to be these kind of non-shared environmental factors. If you had, like, an inspirational teacher, or like you said, if you were sent to different schools for some reason, one of which put you surrounded you with people who had a different attitude to education compared to the others.

Like we were saying at the beginning of the conversation, like, human psychology is so complicated. But I think we also quite like to simplify these things and, and just assume that the factors can be distilled to just two or three different factors and that's always going to be, you know, it's always going to lead you to the wrong conclusions if you do that.

Reflection on school transition and career choices

David Elikwu: Yeah, exactly. And funnily enough, even just from what you were saying, I never really thought about drawing any connection between what I was just saying and my own life, but I think I've kind of lived through that as well, where I started going to one school and then had to switch schools after, I think halfway through year nine or so. And the school that I went to after that was just a much better school, also a much smaller school [00:13:00] where the teachers paid a lot more attention and it was just remarkably different.

And again not necessarily intentional, the school that I'd gone to previously was just not a great school, as an example, I didn't even realize up until maybe six or seven years ago now, which seems like a while ago now, but definitely as an adult that a lot of other schools, let's say in that kind of area didn't have police officers in that school. I just assumed that, you know, that was just a thing. It might not be everywhere. I'm not expecting there's police officers at Eton, but you know, I just thought, Oh, other people that also went to similar kinds of schools, it was going to be the same, like there was a police officer that had an office inside the school. And that's where, you know, that PC that's his office there, and I just assumed that was normal.

And funnily enough also, like one thing that I thought about recently is that I can't even remember thinking about any thoughts about what I was going to do as a job, until after I moved school. Suddenly when I moved school is when, oh, we've got this careers day, and that's when I'm trying to figure out, you know, I'm like 14 at the time. [00:14:00] And that's when I decided I was going to be a lawyer and obviously that went well. And I ended up, you know, working at my dream law firm and all of that. But I can't imagine any of that actually having been the case if I hadn't been forced to, to move school at the time. And so you can just see even within my lifetime, how did the trajectory drastically changes massively without much tweaking of anything else.

Unconscious influence of social norms

David Robson: Yep, totally, because you know, if you don't have a point of comparison, you just assume that you're, your world is the way it is, you know, across much of the country.

Yeah, same with cultural differences and, there's that, I can't remember which Psychologist said this, but it's like, we're like fish, kind of swimming in all of these social factors. So fish don't really even observe the water around them because, it's omnipresent. So it doesn't even seem to be there at all. And we have the same, our attitudes to like the kind of society around us. We just, we're not even aware how it's affecting us because if it's all we've only known, we just can't even imagine that there might be a different, a different way [00:15:00] of seeing things, a different way of doing things.

What is the expectation effect?

David Elikwu: Yeah, exactly. And I think this is actually a really good segue to the expectation effect and this idea that very often the things that we expect or the things that we think can lead us to either to act in different ways or can lead us to subconsciously react to our environment in different ways.

And maybe I'd love if you could just frame the book and what the expectation effect is.

David Robson: Yeah, sure. So I define the expectation effect as this phenomenon where we create self-fulfilling prophecies from our beliefs, and that can happen through three different but interlinked mechanisms. It can be through changes to our perception, to our behaviour, or to our physiology. And the most famous example of this is the placebo effect in medicine, where we, you know, it's now been shown so many times that often, especially in cases like pain relief.

If people expect to receive a real [00:16:00] painkiller, and then they're actually given a dummy pill, they often do see their pain levels dropping quite dramatically. And what the neuro search has shown with that is that it's not just a purely subjective or imagined response. And so it's not just the change in perception, it's actually often accompanied by physiological changes.

So you can see, for example that, when you receive that fake painkiller, the brain can start to produce its own endogenous opioids, neurotransmitters that can reduce pain and can reduce inflammation. Now, what the new research shows is that expectation effects often operate in a very similar way to the placebo effect, can occur in all kinds of areas of life. And that can be your responses to food and changing your diet, your responses to exercise, it can even affect how well you age.

A positive view of ageing can lead to longer life

David Robson: So there's a, a really startling statistic that shows that people who have a positive view of ageing, tend to live [00:17:00] around seven and a half years longer than people who have a negative view of ageing. Those people who really dread getting old and think that it's going to be automatically accompanied by vulnerability and disability without considering all the wisdom that you might have accrued once you get to an older age and some of the advantages, you know, the freedom to try new things to pursue your passions, to grow.

And once again, we see with this ageing expectation effect that that can be linked to changes in behaviour, so if you have a positive view of ageing, you are more likely to kind of take care of your body because you want to kind of live as long as you can, and you feel more capable of doing exercise, but also to physiological changes.

If you're positive about ageing, you're kind of more relaxed as you get older, whereas if you have a negative view of ageing, you assume that you're going to become more vulnerable. You start getting stressed out by all kinds of daily challenges like going to the shops, you know, you think you're going to have a fall or get lost and, you know, that raises levels of cortisol the stress hormone, [00:18:00] which can then cause damage in the long term to your body.

So yeah, it's really, you know, again, we can't, we're often not even aware of the expectations that we're carrying because we just assume that they're objectively true. But actually that's not the case at all, with lots of our beliefs, there might be a small part that's objectively true, but then there's also we kind of load that with kind of subjective beliefs too. And just by altering that mindset, we can often turn the expectation effect to our advantage so we can have better health, better wellbeing, and even live longer.


Understanding placebo effects

David Elikwu: Yeah, and I think a really key point to emphasize here that I think, you know, I've written a lot about this myself, I'm not a science writer, but, you know, at least in my hobbyist capacity. I think one thing that people consistently underrate is the fact that what we're describing, and it could be when if you talk about the placebo effect specifically, but more generally with this expectation effect, it's the idea that this is not just maybe some behavioural science gimmick, and it's also not just, oh, you just happen to believe in something and something happens like it is really that your brain actually has the power to do a lot of [00:20:00] incredible stuff.

And I think you talk about, and you could probably elaborate in more detail, but I think it was a study or just a general fact that where if you give someone anesthesia or if you give someone some painkiller and you give it to them specifically, like a doctor puts the thing in their hand and then they take it themselves, you can give them a certain dose, but if you just give it to them, maybe while they're not looking or while they're not aware through an IV drip and they don't know that it's happening, you have to double the dose, or you have to give them a lot more because actually the gap between what the drug does by itself and what your brain does when it's expecting that there is some healing that's about to happen, is equivalent to, you know, more of the drug. And so actually you have to change the dosage if the person doesn't know they're going to get it, because actually your brain is actually just capable of creating some of these changes for itself.

David Robson: Yeah, totally. And you know, that combined with then the neurological evidence showing that there is this production of the opioids in the brain, you know, we can see that happening. And you can block the, [00:21:00] if you block the opioids using this other kind of chemical then you can block the placebo effect, like all of those strands of evidence together. I think just makes the placebo effect and, you know, the expectation effect by association, like, undeniable.

But I have seen some people who, I would call them placebo deniers who, I don't think they're aware of that research, and so they do just assume that it's just this purely subjective psychological reaction, but actually no, it's really, you know, it's measurable, it's objective and it's changing people's lives. Like, even if you just look at the placebo effect with pain relief, that alone is so important because of people's patient comfort is just so important. And a lot of healthcare professional's job is just making sure that someone's symptoms are manageable. And if you can control that, you know, you're already providing a lot better care.

The psychology of pain

David Elikwu: Yeah. I remember a study, I think it was very unethical, and I don't think it's been obviously not reproduced, but I think it was in Texas or [00:22:00] somewhere in the US and this is probably in the 1950s, early fifties, somewhere about then where, they essentially were doing knee surgeries on people. And I think they just didn't tell some of the people that they weren't really doing the surgery. And so they kind of had three groups of people, one group, okay, they came for some knee surgery, that's what they think they need to relieve some of their knee pain and you give them the surgery. And then there's another group of people where they say they have knee pain and you kind of you give them the anethesia so that they're asleep the whole time. Anyway, you cut their leg open as though you've done something and then you just sew it back up. So you didn't actually do any work, but you gave them a little cut. And then the third group of people, you just don't even do anything.

And actually across all these groups, if they believe that something was done while they were asleep, suddenly the pain is gone and they have pain relief for weeks, just as though they had actually had the surgery.

And I think at that point in time, at least then you start questioning, okay, did they actually need the surgery? How useful is this surgery? Or is this just something that we think we have to do? Did we just [00:23:00] assume that, Oh, this is something we have to do because this person is feeling this pain. But actually if they just think that they're going to get better, and it's not just the power of thinking, it's the fact that, your body does heal itself like, that is something that was going to happen anyway.

And the point is, the belief that that healing is going to take place or has been enabled by medicine, you kind of bolster the, you know, you rally the troops internally and your body starts healing.

The importance of psychological support in medicine

David Robson: Yeah, I mean, obviously, like, I think, because my surgery is not tested in these kind of controlled placebo trials, but there is now a movement to try to do more of them despite, you know, there are ethical concerns about giving people surgery without making an incision, without performing the surgery. But actually, you know, if the patients are informed and you get their consent, it's actually probably more ethical to do that and to prove that the surgery is necessary and improves symptoms over and above the placebo. It's probably better to do that in a small group compared to [00:24:00] just giving people surgery, you know, on a much wider scale without knowing really if it is better than the placebo. I mean there is a strong ethical argument to do that.

I think this is just, the studies that I looked at just show that actually, you know, we should be incorporating the understanding of the placebo effect into medicine in all kinds of areas. So, you know, you don't have to deceive patients to benefit from this expectation effect. Just when a doctor is warmer and more optimistic and encourageing to patients, even if there's no real treatment that they can receive. But if, you know, if you go to the doctors with like a viral infection, and the doctor's like, tells you, Well, I can't give you a treatment, but, like, this is nothing to worry about. You're going to get better, you know, pretty quickly, your body's perfectly capable of defending itself. When you just use those words, those words become biologically active, and actually those patients end up recovering more quickly than the patients who have a cold and distant doctor who treats them as if they were kind of [00:25:00] wasting his time and doesn't provide the reassurance.

You have people undergoing heart surgery, and they recover more quickly if they're given psychological therapy, just before the surgery that helps to explain, you know, why it's so important to receive this surgery? And helps to alleviate some of their worries about their recovery. And then also helps them to kind of have this optimistic plan of what they might be able to achieve at each stage on the road of the recovery.

And what you find with those people is that they leave hospital earlier, which is a great economic incentive because hospital beds are so expensive. They return to work more quickly and you can actually see differences in the way the body has responded to the operation. So, they tend to show lower levels of certain inflammatory markers that, you know, if your inflammation is high, that could make your healing a little slower.

So again, it's biologically active. It's also just making the patients a kind of more psychologically comfortable and it's having real effects on how quickly they can get back to their [00:26:00] day-to-day life.

How powerful the brain is

David Elikwu: Yeah. And there's a lot more that I want to ask you about this, particularly things like gluten allergies, the French paradox, et cetera, et cetera. But I think it might be useful just to ground this quickly because I can just imagine that the sceptics that are saying, Oh, you know, like you say, some of the people that just don't, they're already predisposed not to believe in some of these things.

But I just want to hammer home like how powerful the brain is? And I think part of it, the placebo effect is a bit of a, has become a bit of a misnomer where simply because when people hear the word placebo, they're thinking, Oh, you gave me something and it doesn't work. And that's what placebo means. It's like, Oh, sugar pills or something that doesn't work. And I don't think that's what it actually means.

What it really means is your brain is capable already, your body is already capable of replicating the effects of billion-dollar pharmaceuticals and what you're testing is, can this drug do more than what your body could just do by itself? And it's not so much just like, Oh, like here's some fake stuff and are you going to make [00:27:00] stuff up in your brain and, you know, trick yourself into thinking something like, no, it's like your brain is actually capable of doing a lot of this stuff.

And I think the way I like to think about it, or some of the other things that help me to think about this are, when you think of the brain in other contexts. So for example, if you think of things like pain or fatigue, you know, we talked about the knee surgery as an example, but pain isn't real, right? Fatigue isn't real. These are all things that are actually invented by your brain. Like there's no, when you feel like a pain in your arm or something, let's say it's not distinct from, like there isn't something that's happening in your arm that's distinct from your brain. Like it's your brain sending you an alarm signal telling you, I think something's happened over here, you better check it out because something isn't working right. And so it really is in your head, right. And that's why after a surgery, you might have rehab and rehab is training you to essentially to believe in yourself again. And to know that, okay, here is something that you can do. It's actually okay to walk on your leg and you take it slowly. Because if you don't do that, then, [00:28:00] and you do the same for, for animals, for example, because they're not going to know that they can walk on their leg again, if they already think that they can't walk on it anymore.

And so I think the point is that, yeah, the same with fatigue, you see in boxing, you see in running, that's how people get second wind. Like they felt tired, but that doesn't mean, oh, you're out of juice. Your brain is making a prediction based on how much you've exerted yourself before, how much it sees you exerting yourself right now, and predicting how long can you keep going for without causing any damage. And all your brain is trying to do is just preserve itself, it's trying to preserve your body. And so that's why you have pain. It's sending a signal, you know, alarm bells, something's going on, you better check this out. And fatigue is the same, it's just trying to preserve your muscles, trying to preserve your body. And so it's telling you, Hey, Hey, you might want to slow down, you might want to rest. But you can actually just keep going. If you're trying to win a race or you're trying to get through a boxing match, you can actually just keep going and ignore some of those signals.

Understanding the mind-body connection

David Elikwu: And I think there's two examples that I always love that come to mind, which are about nail guns, and it's just two different stories and one of them, I [00:29:00] think there was a guy that had a nail gun incident. I think he was trying to shoot a nail gun into a wall and it kind of went backwards and hit his eye. And so he had a bit of a headache at the time and later that day, he started feeling a bit of a toothache. And so he goes home to his wife and he tells his wife, Hey, you know, my tooth's hurting a bit. And they decide to see how things go over the next few days. Getting towards the end of the week and his tooth is really hurting. It's been a few days. And so his wife says, okay, you've got to go to the hospital. He goes to the hospital. The nail is inside his head. Like it's in his jaw, pointing up towards his brain. And because he didn't know, he didn't feel like he felt like a little bit of a toothache, but not the kind of pain you might expect to feel if you thought that a nail is stuck, like a nail that's several inches long is stuck inside your head.

And the other example was kind of similar. I think someone shot a nail gun and it ricocheted off something and went into the guy's boot. And so obviously the guy is screaming in pain. Like you can see this huge nail sticking out of his [00:30:00] foot, falls to the ground screaming. He was on a construction site, so everyone else is gathering around. They get him into an ambulance. They take him to the hospital. They take a sore, they cut off his boot and the nail has gone directly between toes. He's not hurt at all. There's no physical pain whatsoever, but he felt the pain. He was experiencing excruciating pain because he thought that he just got shot in the foot.

So the point is that, Like you say, the expectation effect. If you think you've been shot in the foot, you're going to react. Your brain is going to create all the signs that you would associate with getting shot in the foot. You're going to feel the pain. You're going to get the signals that tell you, Hey, you need to go to the hospital, cause that's what's going to save your life. It might turn out that actually you weren't shot in the foot at all.

And so I think it's a similar kind of thing, at least in the context that we were talking about from a medical perspective, where sometimes if you think and expect that a certain situation is true, your body will just involuntarily react as though that is the case and vice versa. If you think everything is okay and you think, Oh, you know, [00:31:00] maybe I've got a little bit of a toothache, you might not realize that there's a huge nail inside your head.

The expectation effect has limitations

David Robson: Yeah, totally. I mean, I love both of those examples. I definitely think I'd be the guy who, you know, when the nail went through his boot was like, writhing in agony.

But yeah, and what I find interesting is then you look at the neurological mechanisms of this and, you know, when we feel anxiety that increases the production of this chemical called CCK, which amplifies the transmission of pain signals. So if you have even like a, you know, small irritation that suddenly becomes a lot more salient to your brain. It's like it's kind of added loudspeakers to that signal and it's really suddenly like occupying your consciousness. This isn't just kind of woo woo, we really understand those mechanisms very well now, like we've observed the effects in trials scientifically, and then we've also understood kind of, what's causing them.

I would just say, like, the point with the expectation effect was also to kind of work out, well, what are the limits [00:32:00] of this? And so, in the book, I really focus on the things that we have studied that do have a plausible mechanism. But say there are other claims that you might see, you know, like the positive thinking will help you to get over cancer.

Well, actually, like the studies that have attempted to show that are very poor. When you look at the whole body of literature, you know, there's no evidence that positive thinking will help you to kind of get rid of a tumor. And we also, there's no real feasible mechanism by which that could occur. Like the body can't produce his own chemotherapy drugs, like in the same way that it can produce these opioid drugs that are already in your brain and are just part of the way it operates.

I've tried to be really careful about, this isn't the case that you can kind of manifest something and whatever you want will become true. But that doesn't mean that it's any less important or relevant. And even if we look at something like cancer care, well, positive thinking isn't going to get rid of the tumor. But actually, placebo effects can be [00:33:00] really important for, say, helping people to overcome the nausea and fatigue that they might be experiencing when they're undergoing treatment and undergoing chemotherapy.

And so, you know, just because it can't necessarily save your life in that context, it could still be, this research could still be really fundamental in ensuring that these people get the best possible care.

David Elikwu: Yeah, exactly. You make a great point. And I think that the key is that we're talking specifically about the things that your brain and body already have mechanisms to do. You can't, you know, create, drugs and stuff that it didn't already have. But if there already is a process in the body for doing a certain thing, let's say releasing ghrelin.

I think you have an example this, but the one that comes to my mind is, you know, that's part of the reason why people say don't chew your food too quickly, because since you were born, your brain, and I actually, I think a precursor to explain is also quite important.

The brain is a predictive machine

David Elikwu: I think you've talked about this as well, but I've read some books by Lisa Feldman Barrett, she talks a lot about this idea that, you know, your brain is effectively a predictive [00:34:00] machine and it's locked in a black box. Your brain doesn't actually have any idea what's going on in the outside world. It's making interpretations of what it thinks might be happening through your body signals. And actually It's not just that, but your brain isn't responding in real time to what's happening in the world. Your brain is predicting in advance what it thinks is going to happen based on everything that's already happened in the past. And so, because, you know, for example, let's say you were hiking in a trail and a rock was going to fall on your head. If you only started reacting once your eyes saw the rock, it would probably be too late and you get squished. But actually your brain is already subconsciously noticing things, you know, some part of your brain might realize, Oh, maybe this rock's a bit loose or, or maybe the place that I am in, this is the kind of thing that happens. And so it's already preparing to recruit some of those muscle fibers and to fire the neurons that would alert your body to make a movement. And then when that is confirmed, then by your sensory receptors, so by the time your eyes actually [00:35:00] see that something is happening, your brain has already prepared to fire those neurons and so your brain is already prepared to initiate that movement.

And I think the same happens in a lot of these areas where, the point being that, your brain is just kind of reacting based on this data that it gets. And so with food as a good example, Is that if you're eating quite quickly, your brain is preparing to, you know, release some ghrelin in order to send this signal that, Hey, you've eaten enough based on how much I know you've eaten in the past, but if you're eating too quickly, you'll eat or drinking water too quickly. And I think maybe this happens to a lot more people where let's say you're out for a run and you're a bit thirsty and you drink loads of water and suddenly you feel full and actually you feel this strange sensation where now you realize you've actually drank too much, but the reason is because you were drinking quickly. And if you're drinking slowly, there'll be enough time for your brain to say, Hey, that's enough. But because you didn't do that, you've already now drunk far more than you needed to. And the reason is because your brain doesn't actually know it. Well, it's not doing it in real time. It's predicting in advance and then using the signal from [00:36:00] different parts of your body to then interpret those signals and to interact afterwards.

Is the brain capable of changing our physiology?

David Robson: Yeah, that's exactly how I see it. And so we know from daily experience that like, or let me put this another way, like people who question, like, whether the brain is capable of changing our physiology? I just would ask them, like, what happens when you think of your favourite food?

The chances are your mouth is going to start watering, your stomach's going to start rumbling. Well, that is an expectation effect. By imagining like that delicious dinner, you're already preparing, your body's already preparing itself for digestion. You know, your saliva contains enzymes that will start breaking the food down when it's in your mouth. You know, your gut is then starting to create all those digestive juices that will continue that process. And the expectation effects that I'm describing are really, you know, no different from that.

And, you know, we also know from, say, studies of amnesic patients who can eat one like big plate of dinner and then it's taken away, they forget what they've eaten and you [00:37:00] give them another one and they will eat it as if they have not had food for the whole day. And then you can take that away and repeat it again and they would eat the third plate of food. Because they don't have the memory of what they've eaten, their brain just isn't updating it's kind of assessment of, it's need for nutrients. And so it's telling them kind of keep on consuming.

Not many of us have like, serious memory problems, but actually, if you're very distracted while you're eating you're gonna form a worst memory And so, you know, if you're working or you're watching TV, you're not really registering properly, what you've consumed. And so your brain isn't able to adjust its perceptions of appetite accordingly. Which is why then you're more likely to snack afterwards, compared to if you were really focusing on your food.

David Elikwu: Yeah, and it's funny, the number of situations in which the brain can kind of subtly malfunction.

The brain's role in physical reactions

David Elikwu: I just thought about the idea that, and this is one of my favourite examples, that, you know, your body has no wetness receptors, right? Your brain is just combining your touch sensors, right? Like your tactile [00:38:00] sensors with your temperature sensors. And it's combining those two things to predict when it is feeling wetness or water. And that's how waterboarding works. Like that's how you can trick someone into thinking that they're drowning because your brain actually doesn't really know what that is. It's just combining these two other things into a sensation of, Oh, I feel this movement on my skin and it has a temperature that's different to the usual temperature. This must be water, like it must be wet. I'm probably drowning right now. And whether you're having a shower or you are drowning at sea, like your brain is kind of just guessing and trying to figure out, okay, what's happening and how am I supposed to respond to that? And so maybe if we then start to connect this to people's daily lives, I think in the same way, there's lots of situations that we might be in.

Actually, perhaps a good example is kind of a little bit related to something you mentioned before, but I think this is from Alia Crum at Stanford's mind and body lab, where they had the study with the milkshakes and actually you can give [00:39:00] people two different milkshakes. And you tell one group of people this is a, a really indulgent milkshake. It's a high calorie drink and you tell the other people it's a diet drink you know, this is a new diet milkshake and their bodies process it differently. And so actually even just going about your daily life, the way that you interpret and the relationship that you have with the food that you eat and the things that you consume actually changes how your body processes that thing. If you think you are having this indulgent snack and it is actually very unhealthy and not very good for you, your body will react appropriately and it will respond in that way. And if you think, Oh, maybe this is actually fine, then your body will also react in that way. And I think you have a good example of this as well.

How enjoyment affects nutrient absorption

David Robson: Yeah, exactly. Like I love that study by Alia Crum, but you know, there's also this study from the 70's that I think is like not, not well enough known, which looked at like the way that people absorb nutrients from their food, depending on whether they find that food appetizing or not.

So they, they looked at anemic women in Thailand and Sweden. And [00:40:00] essentially, they gave you know, each group of women one of three meals. So they either had their kind of favourite meal from that's culture appropriate. So like a Thai curry, for example with iron supplementation within that. Or they gave them the equivalent meal from the other culture, also with iron supplementation, but something that would be a bit unfamiliar and they might not necessarily enjoy so much. Or they just gave them, like, the food had just been blitzed in the processor, so it's like baby food, you know, not appetizing at all, also with the iron supplementation. And then they just tested how quickly these women absorbed the iron from the food that they'd eaten. Now the very worst was the unappetizing dish. So even though it was nutritionally exactly the same, they just didn't seem to take up the iron that was in the food. Their digestion just wasn't working as efficiently.

Next best was the kind of meal from the other culture you know, something that was unfamiliar that they might not have found so delicious. And the absolute [00:41:00] best was when you gave them a really tasty meal from their own culture. And it just seems that the anticipation of that food, the enjoyment of that food was helping them to release more enzymes within their digestive system, that then allowed them to absorb more of those nutrients.

And I think that's so important in modern culture, where you know, people talk of food as medicine, which is fine to a certain extent, if we start to see our food is just this kind of instrumental thing and take all the pleasure out of it like we're just looking at it as if it's a list of, of nutrients, without any celebration or excitement. We're missing out on, you know, a really big part of the meal that's so important for our like, mental well-being, but then also for our physical well-being because you really need to have that sense of enjoyment if you're going to get the most out of the food that you're consuming.

The pygmalion effect

David Elikwu: Yeah, that's such an interesting study. It reminds me a little bit of, and this is slightly different in that it's not within body, but the Pygmalion effect, which is, at least when they've studied it, they look at teachers in [00:42:00] classrooms and the expectation that the teacher has of a particular student can then start to affect the grades that that student gets independent of how smart that student was in the first place. And so if a teacher, and, it makes sense in an intuitive way when you start to think it through, like, okay, if a teacher thinks this particular student is capable, they'll pay them some more attention. They'll help them out a bit more if they have questions or they don't seem to be getting something. They'll pay closer attention to the work that they do. And then suddenly they're getting better grades and the teacher smiles and says, ah, of course my prediction is, is true. I thought this kid was smart and look at them getting fantastic grades. But it's actually just a natural result of, because you already believe that was true, you then acted in a way that was consistent with those beliefs and you brought about the situation that you thought was going to happen.

The influence of teacher expectations

David Robson: Right, yeah. And, you know, the opposite is true, obviously. When a teacher has lower expectations, it can severely damage the child's academic progress. And it's often not in the way we expect. Like, I think we've all had, like, pretty nasty teachers who were actively discouraging But, you [00:43:00] know, though I think it's fairly obvious how they would affect a child's self-esteem.

But those aside, you might just have some teachers who are kind of well meaning, because it's about all the ways that they're kind of subconscious expectations them play out in their interactions. So, if you really believe a child has potential, you might give them longer to answer a question because you kind of have faith that they're going to get to it in the end, they're going to find that solution. If you think a child's, you know, not that bright, you might either just not ask them to answer in class or you'll just let them say a few words And then you'll cut them off and correct them before they've had a chance to kind of think through the problem for themselves. You might not give them such difficult tasks in their homework. You might just kind of give a very bland smile to them and kids can really perceptive. They're very socially sensitive. They know if they're being patronized. And so that in itself can reduce their self-esteem because, you know, they know that they're being treated with kid gloves rather than being taken as serious thinkers. And you know, that's a serious problem. Um, and [00:44:00] it's not easy to correct because often these teachers don't realize what they're doing.

But there had been studies in New Zealand that had just kind of filmed the teachers in the classroom and then showing the teachers, you know, what they were doing and pointed out a few of these quirks and a lot of them are really surprised. They just had no idea that they were treating different students so differently, but afterwards, they were able to correct those behaviours. What you saw was that then just improved the grades of everyone within the class. You know, a minimal intervention really, but it was really helpful for helping to give every child the same opportunity, so that they weren't affected just by these teacher's perceptions, which are often way off, and often shaped by all kinds of implicit prejudices that have no real factual basis.

David Elikwu: Thank you so much for tuning in. Please do stay tuned for more. Don't forget to rate, review and subscribe. It really helps the podcast and follow me on Twitter feel free to shoot me any thoughts. [00:45:00] See you next time.

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