Motley Fool Money - Interview with Dan Ariely: Investing in the Irrational

Episode Date: September 14, 2025

Dan Ariely, a Professor of Behavioral Economics at Duke University, is the bestselling author of Misbelief, Dollars and Sense, and Predictably Irrational. Motley Fool contributor Rich Lumelleau talks with Ariely about the rational and irrational: Inspiration for studying human behavior Swiss Army Knife problem Emotions and investing Extrinsic and intrinsic motivation Host: Rich LumulleauProducer: Mac GreerEngineer: Adam LandfairDisclosure: Advertisements are sponsored content and provided for informational purposes only. The Motley Fool and its affiliates (collectively, “TMF”) do not endorse, recommend, or verify the accuracy or completeness of the statements made within advertisements. TMF is not involved in the offer, sale, or solicitation of any securities advertised herein and makes no representations regarding the suitability, or risks associated with any investment opportunity presented. Investors should conduct their own due diligence and consult with legal, tax, and financial advisors before making any investment decisions. TMF assumes no responsibility for any losses or damages arising from this advertisement. Learn more about your ad choices. Visit ⁠megaphone.fm/adchoices Learn more about your ad choices. Visit megaphone.fm/adchoices

So when we collect data on what it is that companies create and their employees feel about the company that make a dent in alpha in stock market return, it ends up having nothing to do with extrinsic motivation. That was Dan Ariely, Professor of Behavioral Economics at Duke University. I'm Motley-Fold producer Matt Greer. Now, we've had the opportunity to interview Dan Ariely a number of times over the years. He's really great. It has. helping us understand our behavior as investors. Motleyful contributor Rich Lumello recently talked with Haryrelli about investing, including the rational and the irrational. Welcome to Motley Fool Conversations. I'm your host, Motley Fool contributor Rich Lamello. Today on the show, I'm thrilled to welcome Dan Ariely, a renowned behavioral economist, professor, author, and entrepreneur, whose work has reshaped how we think about decision-making, money, motivation, and human nature.

Dan's the author of 10 books, including three New York Times bestsellers, like predictably irrational, the honest truth about dishonesty, and dollars and cents. He's delivered some of the most watched TED talks of all times. He penned a popular Wall Street journal column for over a decade, and he co-founded multiple companies that apply behavioral science in health and finance and technology. Today we'll dive into what really kind of drives our financial behavior, why we often get investing wrong. and how we can make smarter choices in an irrational world. Dan, welcome to the podcast. Lovely to be here. Thanks for the lovely introduction. I've been on a podcast from the Motley Fool a few times, and every time it was fun, so I'm looking forward to this. Excellent.

Well, clearly, as kind of laid out in the introduction, there's a lot of ground to cover, and obviously, as you well know, we're an investing website. So we'll probably kind of gear things a little bit that way. but I'd love to, I'd love to, I mean, it's fascinating your studies. I'd love to kind of jump into what originally drew you to study, you know, kind of human irrationality and maybe touch on how some of your personal experiences helped shape that journey. Yeah.

So the people who are watching us, it's obvious that I have a very funny looking face. The people who are listening to us, it's, you don't, you can't tell. I have half a beard and the reason there are multiple reasons for the half a beard but the simplest one is that I have scars on most of my body

including the right side of my face so I just don't have hair growing on this side and many years ago I was badly burned 70% of my body three years in hospital and hospital really gave me

kind of a magnifying glass on a few topics in society. Pain, control, but also relationships, end of life. And that started my journey into trying to figure out what do we understand and are we really doing our best to provide with the best possible outcomes for our patients or customers, whoever it is. And basically what I learned was that there are lots of people with good intention,

but not enough knowledge. And as a consequence, they think they're doing what's right for their patients or customers, but they are not. In my case, one example for this was the nurses who thought that ripping off bandages quickly

was the best thing for their patients, but it wasn't. And there are many other examples like this. So I'm really kind of a social engineer at heart. I look at the world and I say, what are the topics, what are the areas that I'm, I don't like human behavior, that I think we could perform much better.

And then I say, and do I have the tools as a social scientist to look into this and find out, are we really not performing as much as we could? And do I have the tools to try and fix it? So take a problem like hate. We certainly have too much hate in the world. I wish we had less. I know it's a big problem. I look at it and I say, but you know what?

I don't know what to do. the solutions we have to hate are not relevant. It's very hard to implement them, so I don't know what to do yet. You look at misinformation and say, okay, topic I also being important and so on, I understand it a little bit better. You look at questions about financial decision-making easier. You look at questions about taking care of our health, not as easy as money, but still possible, and so on.

So I basically kind of scout the world for... Problems that I think are big, places where we underperform and places where I think that social science has some lessons of how to do things better. Okay. The old adage goes, it isn't what you say, it's how you say it, because to truly make an impact, you need to set an example and take the lead. You have to adapt to whatever comes your way. When you're that driven, you drive an equally determined vehicle, the Range Rover Sport.

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And in your various books and TED talks and your column in the journal, what do you think is the biggest single misconception that people have about how they make financial decisions or the thinking that goes into financial decisions? So I would say more generally that emotions are a real obvious. for good long-term decisions. Now, emotions have their role. You want to fall in love. You want to enjoy poetry.

You want to go to a museum and enjoy a piece of art. So it's not as if I think we should eliminate emotions, but there are topics where emotions don't help us. Emotions are not designed for long-term consequences, right? And if you look at financial investing, that's one of the areas where emotional just derail us every time. So that will be one. And then I think the second thing is that we don't have a real grasp of compound interest. And I'll give you kind of a story about this.

I think of the human mind as a vintage Swiss Army knife. And let me tell you what I mean. And there are two parts of this, the vintage and the Swiss Army knife. Let's start with the Swiss Army knife. The Swiss Army knife, as a metaphor, is not particularly good at anything. There's not a single task that comes to your mind. Oh, I want to open a can. I want the screwdriver. I say, oh, the solution? The Swiss Army knife.

No, no, no. It's not that good at anything. Its greatness is that it's kind of okay in lots of things, and we can easily carry it with us. And our brain is a decision-making mechanism. It's kind of like that. Not particularly great at anything. quite good in lots of things and we could carry it with us.

That's the benefit. But the metaphor is calling for a vintage Swiss army knife. And what I mean by that is that our brain as a decision-making mechanism developed a long time ago for a very different environment. So, you know, we have a tool to deal with snakes. And we have a tool to deal with hunger and social pressure and trust and betrayal and all kinds of things like that, we don't have a tool to deal with compound interest. You know, so here we only are with this vintage Swiss army knife in an environment that requires

very different tools. We don't have something to deal with credit cards and mortgages and student loans and compound interest and so on. And what it means is that the environment, if the environment wants us to perform better, we need better tools. You know, in the same way that in the physical world, we don't say to people manage. We say, oh, you're not comfortable standing for a long time.

Here's a chair. You can't travel great distances. Here's a bicycle. You know, we build things to take our frail human body and make it work for us in the physical world. In a mental world, it's the same thing. Oh, you can't calculate compound. Let's help you.

Let's give you a tool that does this for you. Instead, we don't do that. Instead, we don't help people make better decision. I think that once we understand how likely we are to fail in the mental world, as we fail in the physical world, that we're frail and, you know, sensitive and so on, then we can start building better tools. I think that's kind of the hope. The hope is to build better tools for this.

So, emotions derail us. Things like having to think about compound interest derail us. We get very much committed to our past choices. You know, again, it's a good thing. You marry somebody. You don't want to wake up every morning and say, did I make the right choice? You buy a stock. You do want to wake up every morning and ask, did I buy the right stock?

But we end up becoming very committed to past decisions we've made, even if they're not in our interest. We don't understand diversification. By the way, the stock market helps us because there are ETFs and mutual funds all that helps us diversify to some degree, but we don't intuitively understand diversification. One of my colleagues at Duke teaches finance. And after the 2007-2008 crisis, he told me that quite a few of his students went into banking, Lehman Brothers. And they called him afterward and told him that almost older stock, older fortune, was in the company's stock. And he said, you know, I taught you for a whole semester.

Like the number one topic is diversify it. And diversification says, don't invest in the company's. that your human capital is involved in. That's not the right approach, not to mention, not too much of... He said, it's kind of amazing. Smart people who went to work in banking fail to understand diversification. It's just very much not in our tool set.

Our tool set is to say, I know about this, I trust. By the way, if we live in a society, what do you want people? To trust too much or to trust not enough? The answer is you want to trust too much, because eventually if people trust too much, it helps. So we have all of these tools that we carry with us that says trust the people you're with. Not necessarily good. So I would say if you ask me, like, what are the challenges?

It's about emotion getting in the way, not understanding compound interest, not understanding the role of diversification, committing too much to our own choices. and staying with them for too long, those will probably be the basic. Yeah. These days I'm all about quality over quantity, especially in my closet. If it's not well made and versatile, it's just not worth it. That's honestly what I love Quince. The fabrics feel elevated, the cuts are thoughtful, and the pricing actually makes sense. Quince makes high-quality wardrobe staples using premium fabrics like 100% European linen, silk and organic cotton poplin. They work directly with safe ethical factories and cut off the middlemen,

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That's a full year to wear it and love it. And you will. Now available in Canada, too. Don't keep settling for clothes that don't last. Go to QINCE.com slash Motley for free shipping and 365-day returns. Quince.com slash motley. Well, and to kind of keep on the theme of looking at some of your writing, in the upside of irrationality, you show that irrational behaviors can sometimes benefit us.

What would you say the positive irrationalities are in long-term investing? Like, you know, for the listener who is, you know, a long-term investor, which is what we encourage, you know, what are the positive irrationalities? Okay. I'm going to tell you something that has been kind of a big focus of interest of mine for the last eight years. Sure. So for the last eight years, I've been looking at data for how companies treat their employees, how the employees feel about the company, and what that means for the performance of the stock of that company. And I have data going back to 2006 until today, and I examine lots of things. And what we find is that some elements of what we call human capital make a big difference.

Others don't. So you ask me, you know, how do we think about irrationality in a positive way? Human motivation is amazing. And I'll put you on the spot if it's okay. Sure. Think for a minute about the three things you're proudest in your... life. Don't say the Matllal. Think about it. How many of them were accompanied by many moments of joy and how many of them were accompanied by more tears and agony and complexity than joy?

In general, when people think about this, they say, you know, most of the things I'm proud of were not just moments of laughter, whether it was starting a new company or writing a book or having kids. Most of these things were difficult and complex and painful. They're more like hiking Everest than sitting on the beach drinking Mohedos. And all of this is just to say human motivation is incredibly irrational. We love things that are complex and difficult and challenging. We like running marathons. We like helping other people.

When you really think about human motivation, you realize that it's not a rational thing. So when we collect data on what it is that companies creating their employees and employees feel about the company that make a dent in alpha in stock market return, it ends up having nothing to do with extrinsic motivation. We usually think, oh, let's pay people more. Let's give them more vacation. Let's give them better health benefits, better retirement benefit. We find zero almost, not zero, but very, very low correlation. predictive value between those elements and stock market return. On the other hand, when you think about intrinsic motivation,

all the things that are irrational, big difference. So, for example, number one thing that we find is important is whether you feel appreciated. You know, from a standard economic class, I said, well, appreciation, maybe. You know, why do you care about appreciation? Turns out appreciation is unbelievably important. Turns out, I told you that salary doesn't,

matter, fairness in salary matters a lot. Feeling proud about your workplace means a lot. Being connected, feeling connected to your direct manager matters a lot. So at the end of the day, what we find is that when you think about stock market returns, a lot of this market is very functional. And I take this data out and I show it to different investment,

managers, and they usually say, oh, you know, I want objective measures. And I say, no, you don't. I said, let's take two very important things. Let's say I want to ask you how much you love your significant other, and let's say I want to ask you in how much pain you are. I say, there's no good objective measures of those. I could wire your brain and measure your senses. Eventually, the love that you feel for your significant other, the best evidence I have is

How much love do you feel right now? It's not how many emojis you send today. And the same thing is true about pain. If I want to understand your pain, it's about your subjective experience. And I say, look, human motivation is eventually about the subjective experience. If you feel that you're being treated unfairly, I don't care if all the objective measures show that you're being treated fairly. Yes, maybe it would be good for lawyers to discuss. but from a human motivation, I care what do you, what do you feel?

So we started an ETF about three years ago. October will have three-year anniversary for the for the ETF. And so far, it looks really good. And I'm very proud of it because, you know, when we started this, I could have written another academic paper. And I could have said, you know, human motivation. Here's another paper on human motivation, and here's another thing. But I think this is like, I hope, kind of the real good evidence that companies should,

first of all, it's a really good evidence, it's a good investment strategy. But it's also a really good point that companies should start looking more internally at human and human capital. And one final thing about this is I think that companies not treating human capital as an asset is an accounting mistake. And what I mean by that is when a company buys a warehouse, it's an investment. When companies invest in their people, it's a cost. That's just a mistake, right? I would want to see on the asset, on the balance sheet, how much you're investing in human capital. Anyway, and I hope we'll get there.

Dan, Errely, it's been a pleasure speaking with you. You know, for the listeners, there's a catalog of books out there, including predictably irrational and the upside of irrationality and the honest truth about it. dishonesty and seven or eight more, TED talks everywhere. It's been a real pleasure bringing you on The Motley Fool again. Thank you so much for your time. My pleasure. It was lovely. As always, people on the program may have interest in the talks they talk about. And the Motley Fool may have formal recommendations for or against. So don't buy ourselves stock space solely on what you hear. All personal finance content follows Motley Fool editorial standards

and is not approved by advertisers. Advertisements are sponsored content and provided for informational purposes only. To see our full advertising disclosure, please check out our show notes. For the Molly Full Money team, I'm Matt Greer. Thanks for listening, and we will see you tomorrow.