in: Behavior, Character, Podcast

• Last updated: May 27, 2022

Podcast #803: How Your Expectations Can Change Your Life

During World War II, Henry Beecher, an anesthesiologist serving in the U.S. Army, noticed that 32% of the soldiers he treated for horrific battle wounds felt no pain. A further 44% experienced only slight or mild discomfort, despite the fact they had shrapnel embedded in their bodies. Beecher hypothesized that the euphoria of surviving battle resulted in the release of a natural painkiller. When morphine was running low in Europe, Beecher thought he could harness the mind’s seeming ability to produce natural painkillers in a different way by injecting soldiers who were about to undergo surgery with a simple saline solution, while telling the soldiers they were receiving morphine. About 90% of these patients underwent the surgery with little or no pain.

Beecher’s field-expedient placebo treatments would go on to open up decades of research into the power of our expectations. On today’s show, my guest will walk us through that fascinating research, and how the connection between the body and the mind is a lot stronger and wilder than we know.

His name is David Robson and he’s an award-winning science writer and the author of The Expectation Effect: How Your Mindset Can Change Your World. David and I begin our conversation with how and why the brain operates as a prediction machine, and how the expectations it generates can shape the reality we experience. We then discuss how even when someone’s pain or condition is very real, the placebo effect can have an equally real effect on their physiology — even when people know they’re taking a placebo. We also get into the “nocebo effect,” where your expectation that a drug will have negative side effects, in fact produces those side effects. From there we turn to how the expectation effect has powerful results beyond the medical world, and shows up in the areas of sleep, diet, and fitness, including how thinking of doing chores as exercise actually increases the health benefits of that activity, how reframing your anxiety can turn it into a performance-enhancing boost, and how your perception of getting older hugely affects how you will actually physically and mentally age.

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Read the Transcript

Brett McKay: Brett McKay here, and welcome to another edition of The Art of Manliness Podcast. During World War II, Henry Beecher, an anesthesiologist serving in the US Army, noticed that 32% of the soldiers he treated for horrific battle wounds felt no pain. A further 44% experienced only slight or mild discomfort, despite the fact they had shrapnel embedded in their bodies. Beecher hypothesized that the euphoria of surviving battle resulted in the release of a natural painkiller. When morphine was running low in Europe, Beecher thought he could harness the mind-seeming ability to produce natural painkillers in a different way by injecting soldiers, who were about to undergo surgery, with a simple saline solution, while telling the soldiers they are receiving morphine. About 90% of these patients underwent the surgery with little or no pain. Beecher’s field expedient placebo treatments would go on to open up decades of research into the power of our expectations.

On today’s show, my guest will walk us through that fascinating research and how the connection between the body and the mind is a lot stronger and wilder than we know. His name is David Robson, and he’s an award-winning science writer and the author of, The Expectation Effect: How Your Mindset Can Change Your World. Dave and I began our conversation with how and why the brain operates as a prediction machine, and how the expectations it generates can shape the reality of your experience. We then discussed how, even when someone’s pain or condition is very real, the placebo effect can have an equally real effect on their physiology, even when people know they’re taking a placebo. We also get into the nocebo effect, where your expectation that a drug will have negative side effects, in fact, produces those side effects.

From there, we turn to how The Expectation Effect has powerful results beyond the medical world and shows up in the areas of sleep, diet, and fitness, including how thinking of doing chores as exercise actually increases the health benefits of that activity, how reframing your anxiety can turn into a performance-enhancing boost, and how your perception of getting older hugely affects how you’ll actually physically and mentally age. After the show’s over, check out our show notes at

David Robson, welcome to the show.

David Robson: Thanks so much for having me.

Brett McKay: So you got a new book out called, The Expectation Effect: How Your Mindset Can Change Your World. You’re a science writer. How did a science writer end up taking a deep dive into the power of expectations over our lives?

David Robson: Yeah, it was a coincidence with an event that was happening in my private life, and then one that was also happening professionally. So in my private life, I had… I’ve been suffering from depression, I’ve been put on these antidepressant pills, and my doctor just happened to mention the one of the side effects that I might experience would be bad headaches. And almost straight away, the next day I started having these migraines that were quite debilitating, actually, really hard to concentrate at work, it felt a bit like an ice pick was penetrating my skull, enough that I would have probably soon discontinued using the pills. But, just by pure coincidence, as I was experiencing this, I happened to be writing an article about the mind-body connection. And I discovered about this phenomenon called, the nocebo effect.

So the placebo effect is where our expectations of a treatment’s success will actually help to make it more beneficial for us. And the nocebo effect is the exact opposite. So that’s when we’re told that we might become ill, that we actually do become ill. And this is a really common reason that lots of people experience drug side effects. So when your doctor warns you that you might experience a side effect like these headaches, that warning, in itself, makes the presence of the headaches a lot more likely for an expectation effect. So, purely for expectation, not for the chemical action of the drugs, themselves.

Brett McKay: Yeah, and I wanna dig more into this placebo, nocebo effect. This is really fascinating. But before we do, I think we need to understand, why is it the placebo effect, or the nocebo effect, can actually be a thing? And you make the case that, the reason our expectations and our mind can influence everything, from our physiology, to how creative we are, how smart we are, even sometimes on tests, it all goes back to the fact that our minds are prediction machines. So how does our brain, this prediction machine… Well, I guess it’s not our brain. So this is… Is it brain or mind? That’s all… I guess it’d be the mind. The mind is a prediction machine. How does this prediction machine construct the world that we experience?

David Robson: Yeah, you can make the distinction between the brain and the mind, but actually, here, I think it really is so central to the brain’s processing, the actual things that the neurons are doing, that you can really talk of the brain as a prediction machine. And what we mean by that is that, it’s constantly forming these simulations of the world around us and preempting what’s going to happen next. So that’s really important in a sensory perception because in lots of situations, almost every situation we find ourselves in, the raw data hitting our eyes and our ears, is just really ambiguous. It’s very messy. And what the prediction machine does is knowing the context of where you are and knowing what it’s experienced previously, it forms these simulations, which then help it to make sense of that sensory data. So it actually tidies up that sensory data and turns it into something meaningful.

And what we’re experiencing, is that combination of the brain’s predictions, those simulations, and the sensory data. We’re not experiencing the sensory data as it is, in its raw form at all. It’s very much it’s being processed and cut up, and edited into something quite different from what you would see if you only saw what is landing on the retina. So that’s how the prediction machine is shaping our sensory experience, but then what it’s also doing is then helping to prepare us for action. So those simulations are then telling the brain what commands to send to the body to change our physiology, so the hormonal balance that’s going to be most useful for the situation we find ourselves in, blood pressure, even the actions of the gut.

All of these things are being influenced by the brain’s predictions, by that prediction machine, and that’s where the placebo effect and the nocebo effect come from. Is because one way of, given information by a doctor, that’s actually changing the brain’s predictions, and then that, in turn, is then changing our physiology, is adapting our physiology.

Brett McKay: Okay, so yeah. This prediction machine, it incorporates a whole bunch of different factors when shaping or constructing reality in our brain. So it’s not only… We use the data we receive from our retina, how we… The light that bounces in our eye and we construct reality with that, it’s also…

Emotions can color our predictions, information from a doctor can color our predictions, consequences that we did an action we experienced this result, that is also going to shape our brain’s predicting machine.

David Robson: Yeah, that’s exactly it. So essentially, we have to use whatever information is available. And like you said, that can just be perceptual or sensory, but also so much useful information comes from our social interactions, our culture, all of these things are feeding into the prediction machine. They’re all helping to calibrate those simulations.

Brett McKay: So you talk about this too in the book, why we would evolve to predict reality, right? You’d think it makes sense that our brains would just be like, “Okay, I’m gonna take raw data from the outside world and construct reality,” but we don’t do that. And because we… We’re sorta guessing, our brain is making these guesses, mostly… Most of the times it’s right, but that means it can sometimes be wrong, but that’s not good. So what’s the benefit of guessing our reality? What do we get for that?

David Robson: So there is some kind of error in these brain’s predictions, but actually it’s accurate enough of the time that it’s still the best way for the brain to process the world. And there’s a couple of reasons why that is. The first one is that it’s actually really efficient. If you’re building these simulations and then you’re receiving the sensory data, the simulations are actually helping to direct your brain to the most important information to process. So the bits of the scene that are surprising, for example, so it just cuts down the kind of amount of data you’re processing because you’re relying on your experiences. But also… And I think this is the main one, is that it just helps us to deal with ambiguity and makes us more adaptive and flexible. If you’re preempting what’s going to happen next, that’s help, just giving you a head start. So if you see a predator coming and your brain is already helping to pump adrenaline through your system, that’s giving you a head start in dealing with that danger. So, it’s very much adaptive, very useful for the way we interact with the world and navigate the challenges around us.

Brett McKay: And even if that predator just turned out to be a little mouse, there’s still a benefit to that, ’cause it’s like, “Hey well, if it was a predator, that would have been really bad, ’cause you would have died.” If it’s a mouse, like, “Well, no harm, no foul.”

David Robson: No, exactly. It’s better to be safe than sorry.

Brett McKay: Right.

David Robson: The classic example is that in a forest, you might be kind of on a hunt and then you kinda jump because you think there’s a snake in front of you. If it turns out that that is actually just a kind of piece of wood or a piece of rope, that’s no big deal, but if you mistake a snake for a piece of wood, well then, if it’s the way around… So if you actually see a snake, there is a snake there, but you see it as a piece of wood, that’s much more dangerous for you. So, we are naturally conservative in our kind of brain simulations, where we do have this kind of bias that we are more likely to see a threat than we would be otherwise, because that just helps us to kind of… It helps to improve our survival.

Brett McKay: Okay, so our brain’s a prediction machine, it’s constantly predicting what reality is, it’s mostly right most of the time, but sometimes there are errors, and from my take on it, these errors can benefit us through the placebo effect, right? Like, you take a sham medicine, it actually doesn’t do anything to you physiologically, but because you think it is, you make this error, this prediction error, it does end up having an effect on you. So let’s talk about the placebo effect, I’m sure everyone has heard about it, but how do scientists define it?

David Robson: Yeah, so the placebo effect as scientists define it, is very much as you described it, is where you receive a sham treatment, but through expectations of receiving some benefits that you do see some noticeable improvement in your symptoms. And so, some of those improvements could just be subjective, maybe you just feel a bit more relaxed, but actually, what we now know is that a lot of the improvements are objective as well, so there’s actual physiological change. This could be, for example, if someone takes a placebo analgesic, a placebo painkiller, you actually see the expression of the brains on endogenous opioids, those are natural painkillers. The levels are increased after you receive this placebo pill. But also, we can see all of those other changes like changes in blood pressure, changes to our digestion, changes to things like the activity of our muscles, all of these things that can be really important, changes to inflammation is one of the main ones.

When we’re ill, we have higher inflammation, when we receive a placebo it can actually reduce that inflammation. And in some cases, the differences can even be visible to the naked eye. People have had rashes and then they’ve received a placebo cream and essentially removed that rash, it’s helped the swelling to go down. So it can be quite profound, the placebo effect.

Brett McKay: Okay, so that’s a good point that I wanna hit home here. Placebo effect isn’t just subjective, though it can be, but a fake treatment can actually have objective outcomes on your physiology, it can change your body physically.

David Robson: Absolutely, and I’m not saying here, but a placebo treatment could cure cancer, we’re not talking about miracles here, but actually the results are still really profound. And actually, another question I’m asked is often, do we have to deceive ourselves to benefit from these expectation effects? And the answer is that you don’t. And so we see that with placebo treatments in medicine, that actually… That it is possible to get a placebo response even when people realize they’re taking a sham medicine. So we call these open label placebos. And one of the most noteworthy studies that I came across was from a trial of people with chronic lower back pain in Portugal, and they were given these clearly labeled placebos. And that was a jar of bright orange pills, and it said placebo pills, take two a day. So there was no deception there at all.

But beforehand, the participants had been given this presentation about the mind-body connection, how the placebo effect works. They had kind of had their expectations raised to what the placebo pills could achieve, and what they found was that after a week of taking these pills, they had a clinically significant improvement in their symptoms, so that in itself was really remarkable, is about 30% reduction in their pain and disability.

Brett McKay: Okay, so you… So yeah, I think often when people think about a placebo, they think you have to not know you’re getting a placebo for the placebo to work, but you’re saying that’s not the case, you can actually know that the treatment you’re getting is completely fake and it will still have a benefit, not all the time but sometimes.

David Robson: Yeah, it sounds incredible but actually, this has been repeated in numerous situations, so people with inflammatory bowel syndrome have really benefited from open-label placebos. It’s actually being shown to help with a certain kinds of fatigue, they can be related to different cancer treatments; having these open-label placebos have been really empowering for these patients, even things like allergies can benefit from open-label placebos. I try to work out in my mind how this could be possible, and I think there’s a couple of mechanisms there, and one is the fact that there’s the ritual of receiving treatments, the placebo pill is capturing that. And we know that actually just the feeling that something proactive is happening that you’re being taken care of, that in itself can help to trigger some physiological benefit, so it can help to do things like reduce inflammation. That’s one potential means by which this can be useful.

And then there’s also a process called conditioning, so if you’ve previously received painkillers, your brain was probably already producing its own endogenous painkillers to help that treatment along a little bit. That’s part of the expectation effect is conditioning. And what seems to be happening then is that even when you’re taking these pills, just the fact that they resemble your previous treatments can take advantage of that, even if you know consciously that they’re not actually the real pills. And so yeah, I think it’s beneficial for a number of different pathways.

Brett McKay: When you also highlight this idea of conditioning, the invasiveness of the placebo can actually strengthen the effect. So a pill, if you take a pill, that can have an effect, so you’re conditioned to think, “Well, if I take a pill, it’s gonna have some sort of effect on me. It’s gonna reduce the pain.” If you wanna go a step above that, an injection. And they’ve actually done this with, I think athletes like, “We’re gonna inject you, we’re gonna tell you it’s an athletic performance drug, but it’s actually just saline,” their level of performance increased significantly. And I guess the ultimate intervention would be a surgery, it’s like a sham back surgery, and as you go up, oftentimes the intensity of the placebo effect also increases as well.

David Robson: Yeah, that’s right, and actually placebo surgeries have been shown to be beneficial in so many different areas; people who have gastric bands fitted to control their appetite, a big part of those benefits that they received of the placebo effect, ’cause you know that if someone’s had a sham operation where there might have been an incision but the band wasn’t actually fitted, you still see a big amount of weight loss after, some reduction in appetite. Also with, it seems like when surgical stents are added for people who are experiencing angina in the heart, that actually, a lot of that pain reduction and improvement in things like their mobility and capacity to exercise, a substantial part of that seems to come from the placebo effect too. So essentially, quite common. And the problem with surgery in the past has been that we haven’t really conducted clinically controlled placebo-controlled trials of surgery traditionally, so we’re only just really beginning to understand how big a part the placebo effect plays in lots of different surgical procedures.

Brett McKay: Well, yes, this is an interesting point you make in the book. Medicine or science uses placebo to test drugs. For a drug to get approved by the FDA here in the United States, it has to perform significantly more than a placebo. So they do these studies, they’re gonna give one group the actual drug, another group a placebo. If the placebo does better then it’s like, “Well, this drug actually doesn’t do anything, we’re not going to approve it.” One of the problems you highlight is that over time, the placebo effect is getting stronger and stronger, so it’s getting harder and harder for drugs to get approved. Can you walk us through this dynamics? I thought that was really interesting.

David Robson: Yeah, it’s actually being seen in a whole bunch of different drugs. We see it with antidepressants, we see it with painkillers, we even see it with some things like epilepsy drugs as well. There’s probably different causes of this increasing placebo effect in each case, but one explanation that I found especially attractive, was this idea that actually what’s maybe causing that increased potency of the placebos is actually our knowledge of the mind-body connection. The research has actually looked at how often the placebo effect had been mentioned in the international media, and they found that in the countries where there had been a lot of media coverage of the placebo effect in the mind-body connection, that actually it was in those regions where the placebo effect had increased most in these clinical trials, which is quite remarkable. But I think then that also ties in very nicely with these studies of the open-label placebos, because it’s almost like just once you know that your brain has this capacity to heal your body in some way, that that’s empowering enough that you can see these benefits, and the more people have realized that over the last few decades with all of these documentaries and magazine articles, the more they’ve experienced that.

Brett McKay: Are doctors starting to use placebos just proscriptively, like instead of just giving a drug, they’re just starting to prescribe placebos? Is that happening? ‘Cause that’s an ethical quandary, right?

David Robson: Yeah, it’s a real ethical issue, and actually, I think at least in the UK, a doctor shouldn’t be prescribing a placebo and telling the patient that it’s an active drug. Now, whether doctors actually do that is another question. I have seen a survey that suggested quite a big proportion of doctors say that they have given a placebo at least once in their career. How they got around the ethical quandary, I’m not sure. Sometimes I think it could just be that they prescribe something like a vitamin pill, and they just tell the patient not necessarily dishonestly, “Oh, this could help you to feel better.” So they’re not making any grand claims, but they’re just saying, “Oh, this might be useful to you,” and then I think the patient could still benefit from the placebo effect there without having been overtly lied to. It’s not as if they were claiming the pill was something that it wasn’t, they were being vague enough there for it to be just about ethical.

But actually, I think there’s a lot more excitement now in ways that we can use these open-label placebos, and one of them is to reduce opioid addiction. So there’s a study in the US, at Harvard University, that looked at people who are in rehabilitation that suffered from various types of injuries and they were taking opioid drugs, and the scientists prescribed, first of all the kind of real drugs, but they accompanied that with an open-label placebo pill, and to strengthen the association even more they also ask the participants to sniff the really strong scent of cardamom. Now, what this was doing was conditioning the patients to associate pain relief with the smell and the placebo pill.

And then after a few days, they just… They didn’t tell the patients they couldn’t take the original drugs, but they tried to encourage them not to. So they tried to encourage them only to take the placebo pills and to sniff the cardamom as well, and actually found a really big benefit there. So actually, a lot of the patients were really able to experience exactly the same pain relief with a much bigger reduction in that dosage through this open-label placebo effect.

Brett McKay: We’re gonna take a quick break for a word from our sponsors. And now back to the show. Okay, so we talked about placebo, so the placebo effect can have an objective effect on your physiology. Let’s talk about the nocebo effect. What are some examples of the nocebo effect as the opposite of placebo? What are some examples you came across in your research?

David Robson: I mean, the big one was that kind of personal experience, which then I found actually had played out in the research as well. So that’s this idea that actually the warnings that were given about the side effects of drugs, that actually they can create those side effects. So the headaches that I was experiencing when I was on my anti-depressant pills, they were almost certainly the product of my expectations, not the chemical effect of the pills. And we know that that can actually be reflected in these objective changes in the brain’s physiology, so things like the vasodilation and constriction in the brain seems to respond to these expectations of having a headache. And so, it can actually produce real changes that would produce real pain. There’s no way that this is kind of imagined or malingering. People who are experiencing nocebo effects are really suffering the real symptoms, I think that’s really important to emphasize.

But there are lots of other examples, and I think some that go beyond just kind of the clinic. I think like we’ve seen a big rise in things like wheat or gluten sensitivity. Now, some of these people really do have a kind of direct allergic reaction to the components of wheat, especially the gluten protein. But actually what the research has shown is that a lot of people with wheat sensitivity, they actually showed the same symptoms even when they are given a placebo pill… A placebo food. So that doesn’t include any wheat products at all. And so it really seems that for these people, it’s the expectation that they are going to become ill that’s leading them to have all of these horrible symptoms. And it could be that the huge amount of media coverage we’ve had around wheat sensitivities has actually implanted that expectation in their minds and is then contributing to these symptoms and has contributed to the huge rise in the number of people reporting these illnesses.

Brett McKay: And you also make the case that understanding the nocebo effect can also help individuals with chronic pain, how so?

David Robson: Yeah, because one of the problems when people experience chronic pain is that they catastrophize their feelings. And I can totally relate to this, and I don’t have chronic pain, but absolutely when I experience migraines, for example, I do tend to tend to catastrophize that feeling. So it’s all of those concerns that you might have and those expectations that may be like the pain is just never going to go away at all, but if you have a kind of flare up that is just never going to disappear and that you’re always going to be in that kind of agony, that’s the kind of catastrophic thought they can really contribute to your pain. And what we know is that when we have these negative expectations and the more anxious we become about a symptom, the more the brain responds in a way that will then amplify the pain signal. So it actually releases this chemical called CCK, that is kind of like adding a loud speaker to our pain nerves and is amplifying the signals that they’re sending to the brain and just increasing the experience.

So that’s the explanation, and then the interventions is really aimed at helping people to just avoid that catastrophic thinking. So, trying to get them to be a bit more objective, to try to remember times in the past where they might have had a flare-up, and then to also remember when it dissipated that pain and to realize that the pain may not be there all along. And also to sometimes realize that pain can be functional even. So, just telling people that maybe their pain isn’t coming from tissue damage and they don’t have to be so worried about that pain as they are, that it might not reflect the kind of serious injury that’s kinda getting worse and worse, that it could have this psychological component, that realization can also help people to manage their symptoms.

Brett McKay: So the intervention is that simple, just talking to a doctor saying, yeah, actually, it might not be a big deal and that can have a dramatic effect?

David Robson: Yeah, it really is. I mean, it’s very similar, I think, to the cognitive behavioral therapy that we might experience about dealing with things like depression or anxiety. There is now a lot of research showing that a similar process of talking to a therapist and helping to kind of unpack all of those thoughts and fears that you might have about your symptoms, that that can be very useful.

Brett McKay: You also said about how the nocebo effect likely plays a role in insomnia, how so?

David Robson: Yeah, I mean, it plays a role in insomnia in multiple ways. I think the person is that if you… Once you start becoming anxious about not getting enough sleep, those kind of negative cycles of thinking, that kind of rumination is going to make it much harder to fall asleep at night. So, as soon as you’ve been laying awake for a few minutes, not being able to go to sleep, you have all of this catastrophic thinking that then kinda keeps you awake for much longer. And amazingly, there have been some studies that have shown that in these cases, actually, consciously just trying to stay awake can help break that cycle of thinking. And ironically, it means that you’ll be then quicker to get to sleep afterwards, so you really do just want to kind of try to break that negative cycle of thinking, however you can, break the rumination to try to improve your insomnia.

But even more intriguingly to me is the fact that often, the symptoms of sleep loss, that can also be the result of an expectation effect. So when people who’ve had a disturbed night, if they catastrophize the thinking about that sleep loss, and if they really focus on it and they expect to suffer from a bad mood, poor concentration, serious fatigue throughout the day, they’re much more likely to experience that. And actually a lot of these people who we call complaining good sleepers, because if you put them in the lab you can see that actually these complaining good sleepers often do get seven or eight hours sleep at night. But actually they can even… Those negative expectations can even influence things like the higher blood pressure that can often come from insomnia. So it’s a combination of subjective and objective symptoms, again, that are resulting from our expectations.

Brett McKay: And then there’s also people who don’t sleep well at night, don’t get any sleep, but then they wake up, they feel fine, and they don’t have any of those ill effects of not getting enough sleep.

David Robson: Yeah, that’s exactly it. So we call these people the non-complaining bad sleepers. And despite the fact that they might have really disturbed sleep, they are remarkably free of any ill effects. So obviously, the best combination is to have great sleep and great expectations of your sleep. But these people who have bad sleep but actually have a positive attitude, they fare almost as well.

Brett McKay: Now, reading about the placebo and nocebo effects made me start to re-evaluate all of this health tracking we’re doing with our smartphones. Because I can see it just messing with people’s minds. I think a lot of… If you have an Apple watch, you can track your sleep. And let’s say you wake up and your phone says, “You didn’t get enough sleep last night.” I could see it as just like, “Wow, my day’s gonna be crappy. I’m gonna be tired. My workout is not gonna be good.” I guess there’s heart rate variability, which is supposed to show how fatigued you are. I can see someone looking at their phones like, “Oh, my heart rate variability sucks. I’m gonna have a bad training session.” And then they have a bad training session. So I’m wondering if this health tracking might backfire on us. Had you come across any research on that?

David Robson: Yeah, I had come across researchers expressing concern about this and it totally makes sense to me. I think the problem is that often the kind of trackers that we’re wearing, they’re not to the same standard that you would have in a scientific laboratory, so there’s lots of room for error in the readings that we’re getting. And sometimes that could be beneficial. Maybe you’re telling people that they’ve had more sleep than they really have had and then that might actually improve their functioning in the day. But equally, you could have someone who has slept pretty well, but for some reason, some fault with the device, it’s kind of over-estimating how disturbed their sleep was. And then that kind of obsessive anxiety about that, constantly checking it, then that’s going to contribute to a nocebo effect and could reduce wellbeing in the long term.

And this is really like where… It’s the reason I wrote the book, was that actually I find the placebo effect and the nocebo effects in medicine really fascinating. But actually, I was tracking all of this research that showed that it’s just our expectations are playing equally important roles in all other areas of our lives, including fitness. There’s one study recently from Stanford University where they got participants in the lab and they gave them a genetic test. And some of the participants were told that they had a good version of this gene, CREB1, that should improve their endurance exercise capacity. So we know that these people do… Generally do a bit better on the treadmill and it even relates to some physiological measures such as the kind of gas exchange within the lungs.

Other people were told that they had the bad version of the gene, so they were gonna find the exercise harder. They just weren’t naturally so cut out for exercise. So they did the gene test. The results were recorded but the feedback was… It was sham feedback. It wasn’t the real result that they had received. And then the researchers put these people on the treadmill and actually measured their physiology. And they found that those expectations were really important in determining their actual performance. So how long they could run on the treadmill, how efficient their lungs were at exchanging oxygen for carbon dioxide. Now, all of these things seem to depend on their expectations. And in some cases, actually the expectations were much more important than the actual gene they were carrying.

Brett McKay: Yeah, that’s another source of nocebo, the genetic test you can take that can tell you, “Oh, you have this gene for aerobic activity as opposed to anaerobic.” That can mess with you as well.

David Robson: Yeah, totally. And what worries me about this is that it’s quite rare for something complex, like physical fitness to depend on just one gene. So probably it depends on tens or hundreds or even thousands of genes. But the genetic test that we’re doing at the moment often just cherry-picks a few of these genes. So we might actually be giving people false feedback unwittingly, that could then be damaging their performance or even their overall kind of enthusiasm and motivation for doing exercise because they’ve been given this inaccurate information.

Brett McKay: Well, another area where you saw the expectation effect influence fitness is with a research on housekeepers at a hotel. Tell us about that. I thought that was really interesting.

David Robson: Yeah, so this is really looking at the long-term effects of our exercise and it seems that expectations play a huge role there as well. So these researchers from Harvard University, they visited seven hotels in total. In three of the hotels, they kinda told the hotel cleaners absolutely verified scientific facts. But they just explained to them that the work that they were doing, which didn’t really feel like exercise, it didn’t feel like going to the gym. They weren’t interpreting the physical activity as being like going to the gym. But the researchers told them that actually, they were burning a lot of calories. They were exercising their hearts and lungs, and that over the course of a week, they were easily getting the same amount of exercise as was recommended by the US Surgeon General. So it was really important. It was really a good physically active job. And they just weren’t appreciating that exercise as much as they could be.

They left some flyers and posters around the hotels so that these cleaners could remind themselves of those facts. And then a month later, they came back and measured their physiology. So things like their blood pressure, their BMI, their body mass index and the kind of hip to waist ratio. And in all of these cases, they actually saw that despite there being no real difference in the cleaners’ lifestyles, just the change in expectations seemed to have made them a bit more healthy, a bit fitter than they had been before, compared to cleaners in the other hotels who hadn’t been given that positive information.

Brett McKay: Alright. So thinking of your just daily chores as exercise can prime your body to actually think of it as exercise?

David Robson: Yeah, exactly, and actually, I think I call this invisible exercise, and I think that’s a huge load of it that we all do about acknowledging that. So carrying the groceries, walking to the bus stop or the train station, standing on the train, if you have to during your commute, playing with the kids, doing DIY in your house. All of these things are exercise, but we just don’t see them as exercise. We don’t really consider that they’re actually benefiting our bodies, and if we did reframe that interpretation, we could actually get more benefits from that physical activity.

Brett McKay: Any insights from research to how the expectation effect can influence our diet? I know a lot of people, they wanna eat better. Anything there that the expect… We can re-jigger the expectation effect to help us diet it better?

David Robson: Yeah, there’s loads. There was a study from the ’70s that just looked at people’s attitudes to the meals they were eating, and what they found was the people who saw the food as being nutritious and kind of a treat that they actually absorbed more iron from their food than people who didn’t like the meal that they were eating. It seems to me that the explanation there, although it wasn’t tested, is quite obvious. It’s that when you have this kind of healthy anticipation of what you’re going to be eating, you’re producing more digestive enzymes that help you to extract the nutrients. So pleasure in the food we’re eating and having a good attitude to our food, that’s definitely important physiologically as well as mentally.

But there’s also some fascinating research on hormonal response to food, and this in particular looked at the hormone ghrelin, which is called the hunger hormone, because it stimulates apetite. And essentially, when you eat a meal, you want your levels of ghrelin to drop, and that is what happens when we have a big satisfying meal. But what the research has found was that actually our expectations can shape that hormonal response. And they found that when people were drinking milkshake that was labeled in this really insipid way as this kind of sensible health shake, and they were told it had a few calories and I wasn’t made to feel very appetizing, that actually, just those expectations caused by that label, really reduced the benefit of the meal for the ghrelin response. So even after eating that milkshake, they still had high levels of this hunger hormone that was stimulating their appetite. And again, I think that really shows that even when we are dieting, we really want to eat foods that feel satisfying and pleasurable, and we want to increase our psychological anticipation of that meal to be sure that the body can respond in the best way possible to the nutrients that we’re eating.

Brett McKay: Yeah, and this is interesting, the word that you used to describe food can affect that, so, yeah, you gave an example here. Light and low carb green beans and shallots, lighter choice zucchini, that’s not gonna produce the satiating result that you want. But if you describe it as zesty ginger turmeric sweet potatoes or sweet sizzling green beans and crispy shallots, like oh yeah, it causes that response in us.

David Robson: Yeah, exactly, and I think, I guess she’s famous in the US, Nigella Lawson. The way she describes food in this very sensual way, what this research shows is that doesn’t just make it more appetizing, it can actually change how we digest and use that food and that energy that we’ve eaten.

Brett McKay: Alright. When I drink my protein shake, I’m gonna say, “This is a thick, delicious milkshake.” We’ll see if that does anything. [chuckle]

David Robson: That’s exactly it. Yeah. [chuckle]

Brett McKay: So you mentioned earlier this whole research into the expectation effect started off with you dealing with depression, and particularly the placebo or the nocebo effect you had to the drug you were taking. Has there being any research done on the expectation effect with just in regards to anxiety and depression directly?

David Robson: Yeah, this really helped me actually. So I actually, before I started writing the book, I’d already kind of weaned myself off those antidepressants, but I still had bouts of anxiety. I’d feel very stressed when I had to do things like public speaking. So I was really pleased to find that there was a lot of research on the ways that we can turn stress and anxiety to our advantage by using the expectation effect. And I think the danger, and I was quite worried about this to start with, was that it was this research was gonna just suggest that you kind of try to have a positive attitude and just ignore the stress and tell yourself you’re gonna be brilliant and you will be, and that’s how it was. In reality, the research isn’t asking you to do that at all. It’s much more kind of asking you to set realistic expectations. And essentially it all revolves around this idea that our stress response evolved for a good reason. It’s adaptive, and actually the changes that we experience that might be uncomfortable, can also be useful. So if you have that beating heart, which can feel quite scary when it’s racing because you’re nervous when you’re on stage just about to speak, well, actually, that is helping to pump oxygenated blood to your brain, which is fueling your thinking.

It’s keeping you kind of on the ball. Similarly, things like the hormone cortisol that makes you feel quite an edge, but that’s also just sharpening your thoughts so that you’re more likely to be engaged with the audience while you are giving your talk. What the research has found is that just encouraging the participants to recognize those potential benefits of the uncomfortable feelings that they were are experiencing, that that in itself could then improve their performance and it could also change the physiological reaction. It kind of just muted it a little bit so that you were still feeling charged up, but you weren’t kind of descending into that panic that can be a real problem for people who suffer from anxiety. And even more importantly, it also changes the physiological reaction after this the stressful event. So people who are able to reframe their feelings in this way, they actually recover from the stress a lot more quickly. So their body can go back to all of those other important functions like…

Digestion and tissue repair that it would put on hold when we’re feeling stressed. And what this seems to do then is actually reduce the long-term effects of anxiety and stress. So people who are able to reframe their feelings in this way, they are less likely to experience some of those things like a high risk of burnout or even a high risk of cardiovascular disease that would normally come from people experiencing stress and anxiety.

Brett McKay: Yeah, Dr. Kelly McGonigal wrote a book about that, the Upside of Stress, and her big thesis there is, yeah, what you were saying, reframe the stress response to the challenge response. So instead of interpreting these feelings, and not only emotional but physiological feelings as something bad, reframe it as, “This is actually my body and mind is getting ready to do… Take on this challenge.” So this is actually a good thing, and it has all these beneficial effects that you talked about.

David Robson: Yeah, that’s exactly it. And I think it’s also about reframing the situation sometimes too. So I think, in the past, when I was doing public speaking, I would feel this sense of dread and I would kind of feel angry with myself for having agreed to do the event and it was a very negative attitude. Whereas actually, I’ve changed that now to recognize that this is important for my personal growth, that I’ve got this message that I want to communicate to people, and it’s actually a privilege for me to be able to do that. And then I tell myself that actually, the stress that I’m experiencing, that’s because it really matters to me and because I want to do the best job I can, and it’s actually helping me to do that. So it’s that overall change in mindset that I think has been so powerful for me personally.

Brett McKay: Now, I’ve been doing that with my own kids. If they have a test, and they’re like, “I’m feeling nervous.” I’m like, “That’s good. You’re actually… Your body, your mind is getting you ready to take on this challenge.” Or I coach flag football, a bunch of 11-year-old boys, and before a game starts, they’re like, “I’m feeling really nervous and got butterflies in my stomach,” and then I try to reframe it. It’s like, “That’s okay. You’re getting ready to take on a game. You’re having the right response. Now, take that energy and make it useful in the game and to play your best.” And it seems to work. It seems like they’re catching on.

David Robson: Yeah, I think it really is powerful and actually, maybe it’s a bit cliche, but one of the researchers put it like this, that when you have those butterflies in your stomach and you change your mindset, you’re getting them to fly in formation, and I quite like that metaphor actually. It’s just that you’re actually… You’re turning… What could be uncomfortable, you’re turning it to your advantage.

Brett McKay: So let’s talk about aging because I thought this is was really fascinating. What effect does the expectation effect have on our physical aging?

David Robson: The expectation effect is hugely important for our physical aging in a way that though I was initially really skeptical because it’s not often you see such big effects in science. But actually, it’s been replicated, reproduced and then we know the mechanisms now. So it’s very good science. But essentially, in 2002, there was a study of longitudinal data. It’s a study that looked at, I think around 1000 participants over the whole course of their life. And it’s around middle age, these people who had been asked about their expectations of what would happen in the next few years as they got older. Do they think their life was gonna get better or worse, or stay roughly the same? And what they found was that the people who expected their life to get a lot worse as they get older, maybe because they are associating old age with things like disability, and vulnerability, that they actually lived for seven and a half years less than the people who had the positive views of aging, so a really big difference in lifespan. Now, what’s happened since then, apart from the replications that I mentioned, is scientists have also looked at the mechanisms behind this, and some of them are behavioral mechanisms.

So if you have a very defeatist attitude towards aging, you’re just less likely to do exercise or to eat a healthy diet. You’re gonna kind of let yourself go more easily, and that’s what’s gonna then have a knock-on effect with the diseases that you suffer from and your ultimate longevity. But equally important, there’s a direct physiological mechanism here. And what happens there is that if you feel vulnerable, all of the challenges around you are actually gonna feel threatening and dangerous, and you’re gonna have a heightened stress response. So it’s gonna be more extreme in the moment, and you’re gonna experience that again and again. If you’re just walking to the Post Office, going to the supermarket and you’re worried about getting lost or having a fall, each time you’re going to have a heightened stress response. And over time, those high levels of cortisol and high levels of inflammation, they are going to bring about bodily wear and tear that actually makes it more likely that you’re going to experience different diseases from cardiovascular illness to Alzheimer’s disease, and we can even see these changes in the cells themselves.

So scientists have been able to kind of chat epigenetic markers of aging, so changes to the way that genes were expressed over time, follow a similar pattern as people get older. What you find is that that epigenetic clock is actually ticking a lot faster for the people with the negative views of aging compared to those with the positive views of aging. So it’s actually changing their physical aging at the cellular level.

Brett McKay: Okay. So if you think aging is gonna be terrible, then it’s gonna be terrible and you’re actually gonna age faster, basically?

David Robson: Yeah, exactly, and I think what’s important to emphasize here is that the people who see a positive view of aging, I don’t think that they’re really denying that. They’re actually, you do have a heightened risk of certain diseases as you get older. So it’s not totally irrational to worry about getting older, but I think what these people are also doing is recognizing that there are lots of benefits to being older as well. You may have more free time to kind of grow personally. You have greater wisdom. There’s been lots of study studies showing that actually older adult’s decision-making skills are far superior to younger adult’s decision-making skills. Your general knowledge is greater. Your vocabulary is greater, so you’re more expressive in your 70s than you ever were in the rest of your life. And so I think these people are just kind of recognizing that the good comes with the bad, and actually there’s still a lot of opportunity for excitement and growth as they get older, and it’s that that’s really been helping to protect them from some of the things that the people with the negative views are experiencing.

Brett McKay: Well, and also too, it’s not only does our outlook on aging effect us physically, but it also can affect us mentally. I think we have this idea, as you get… As you age, you’re gonna get mentally slower, you’re gonna be less creative, less vibrant, but if that’s what you think, it’s gonna be a self-fulfilling prophecy. But those who have a more positive view of aging, they don’t tend to have that mental slow down that we often think happens.

David Robson: Yeah, exactly. I think the big one is memory. So what scientists have shown is that older adults often just stop relying on their memory prematurely, they’re so worried about forgetting that they use those kinds of physical crutches to replace their memory, so things like the GPS in the car, or they’ll note things down in a physical list rather than trying to remember them mentally, and it’s use it or lose it, essentially. So the more you start to rely on these crutches, the weaker your memory is gonna get and then that becomes the this self-fulfilling prophecy.

Brett McKay: So there’s something that reminds me of, is something my wife and I like to do when we’re watching old movies, I’m talking about like from the 1940s or 1950s, and there’s an older person on there, they just look really old, they’re all hobbled over, the guy will have a cane, the grandma has got a shawl around her shoulders, and they talked like this, and you think, “Man, they must be really old,” and then they finally reveal how old they are, and they’re like, “I’m 65 years old,” and you’re like, “Wait, you look like you’re 90.” And I think what happened was, 75 years ago, people expected to be old at 65, and they expected themselves to get slow and frail and diminished, so they experienced old age that way, and nowadays, we expect to be vibrant longer, so you got 70 year old grandmas wearing tank tops doing Tae Bo. And so I think that just goes to show you the powerful effect expectations can have in both our physiology and our psychology and our experience, and what we expect becomes a self-fulfilling prophecy. Well David, this has been a fascinating conversation, where can people go to learn more about you and your work?

David Robson: Cool, so the book should be available from all good bookstores, at Amazon, Barnes & Noble, wherever you would normally go to get books. You can also find more information on my website which is, that’s R-O-B-S-O-N, you could also search for it on the Henry Holt website, which is my publisher, and I’m on Twitter d_a_robson and also also on Instagram, David A Robson.

Brett McKay: Fantastic, with David Robson, thanks for your time, it’s been a pleasure.

David Robson: Thanks so much, I’ve really enjoyed the conversation.

Brett McKay: My guest here is David Robson, he’s the author of the book The Expectation Effect. It’s available on and book stores everywhere, learn more information about his work, check out his website,, also check our show notes where you find links to resources where we delve deeper into this topic.

Well, that wraps up another edition of the AOM podcast, make sure you check out our website at where you can find our podcast archives, as well as thousands of articles written over the years about pretty much anything you think of, and if you’d like to enjoy ad free episodes of the AOM podcast, you can do so on Stitcher Premium. Head over to, sign up, use code MANLINESS at check out for a free month trial. Once you’re signed up, download the Stitcher app on Android and iOS and you start enjoying ad free episodes of the AOM podcast. And if you haven’t done so already, I’d appreciate if you take one minute to give us a review on Apple podcast or Spotify, it helps out a lot. And if you’ve done that already, thank you, please consider sharing the show with a friend or a family member who you think will get something out of it. As always, thank you for the continued support. Until next time, this is Brett McKay reminding you to not only listen to AOM podcast, but put what you’ve heard into action.

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