This is Hidden Brain, I'm Shankar Vetanthu. People in romantic relationships often share things in common. A love with the same sports team, maybe the same religion, sometimes a common profession. But for some couples, the similarities go further.
The girl that I'm dating, now we have the same birthday. This is kind of cool. My fiancé, Israel and I have the same birthday, which is something we discovered on our second day. You could say this isn't so surprising.
There are lots of people in the world, and sooner or later, some people are going to get together with others who happen to have the same birthday. But there's evidence this may be more than just a coincidence. Having a common birthday seems to actually draw people closer to one another. When I first went to a new hairstylist, we found out that we have the same birthday, and we call each other birthday twins.
And I wound up going to that hairstylist for years, even after she switched to the lungs, even after we moved, I would drive 40 minutes to go get my hair cut by her. Some people see so much significance in shared birthdays, or even shared numbers in two birthdays, that they select dates for important events based on those patterns. My birthday, my wife and I share the same birthday till I sixth, and we are also married on that day. My birthday is October 27th, and with my first husband, his birthday was September 27th, and we had the opportunity to get married on August 27th.
It was a no-brainer. We decided to do that. The woman you just heard, Genetta Cravens from Oklahoma City, says her love for people with the same birthday extends beyond her love life. October 27th is also Teddy Roosevelt's birthday, and so I've always felt a little affinity for him and for his leadership.
Shared birthdays, in fact, aren't the only thing that draw people closer to one another. Genetta also finds herself drawn to people who happen to have the same name. When I meet another Genetta, there's an automatic, like, oh my gosh, I can't believe we have the same name, and it happens to be that we have the same spelling, and I'll tell you, only that two people have the same spelling of me, but I can tell you who they are, and I felt an automatic kinship. These unexpected connections with strangers can be lovely moments, but there's something else that works too, something we may not be aware of, something that affects all of us.
In Greek mythology, the hunter Narcissus was so enamored of his own beauty that he fell in love with a reflection of himself. Modern psychology shows that we all have a little bit of narcissism in us, most of us like people who remind us of ourselves, whether that someone else with the same name, or someone with the same birthday. Most of the time, such self-love is amusing and harmless, maybe even beneficial, a sign of good self-esteem. But there are times when falling in love with ourselves, or with people who remind us of ourselves, can be a real problem.
This week on Hit and Brain, what we are calling the Narcissus Effect. Researchers have long observed a tendency for people to be drawn to others who are like them in some way. When we hear someone else has the same birthday, or the same name, we feel a little tug of kinship. Some of us might even be drawn to move to states that sound familiar.
There's at least a modest tendency for women in Georgia to gravitate towards Virginia, to gravitate toward Virginia, and the more closely the name resembles a state the bigger the effect appears to be. This is Brett Callum. He's a professor of psychology at Montgomery College in Maryland. He studies something called implicit egotism, which is the idea that many biases are unconscious, and one very well-studied bias was egotism, valuing the self favorably, protecting the self and so forth.
And so we simply got the idea that there's several different things that at least to some degree reflect the preference for the self and an attraction to things that resemble the self. Like having an affinity for someone with the same birthday, or someone with the same name, or even going into a profession that sounds like an echo of your name. So we originally looked at whether people named Dennis or Denise gravitate toward dentistry, but we learned pretty quickly that it's really hard to get data on those things. So you know, there aren't great directories of medical professionals.
There is a guy named Abel who was able to document. I was reviewing on his paper. So now every time you say this, I'm going to jump in and say a guy named Abel who was able to do something. He was able to do a lot of things.
He showed that people whose last name is Doctor, or whose last name is the word lawyer, the name lawyer gravitated toward those two professions. There are lots of other examples. Brett looked at a massive database of millions of Americans, names from the recently released 1940s census, to examine if they were broad patterns like carpenters working in carpentry, bakers working as bakers, butchers working as butchers, miners working as miners working as masons. So we looked at every surname there is, currently the top 2000s surnames that happens to be a career name.
And we looked at all of them. They're 11 of them that are pretty common. I just listed a few. And for every single surname in the 1940 census with something like a, I think it's 130 million people, we were able to show that for every single surname, there was at least a weak tendency for people to gravitate toward careers that perfectly match their last names.
So the obvious thing to say, of course, is that the reason you have a slightly larger number of carpenters, b-carpenters, is that the name carpenter probably originated from families who were in carpentry. And so there is some kind of ancestral connection to the profession that is driving both the names and the choices. Quite possibly. But if you do the math, you pretty quickly say it gets to be a pretty tiny percentage of people.
So if you assume that even over 10 generations, there's a 50% chance that you did what your dad did and a 50% chance that he did what his grandfather did, which is probably higher than reality. You're talking about a probability of less than one in a thousand already over 10 generations. In other words, surnames are so old and they change hands, you know, when a woman and carpenter marry the county farmer, for example, that that's really, it really just can't account for an effect anywhere near this magnitude. Brett Palimas looked at large data sets and public records like the Social Security death index or state marriage records, databases with information about millions of Americans, and he and his fellow researchers have seen all kinds of funny effects.
Like for example, one listener called in to say she and her husband were both born on the 25th day of different months. This isn't as uncommon as you might think. Beyond what you might expect by your chance, there's about a 7% bias in that direction. So if you should have a thousand people doing that, you have a thousand 70 people doing that.
If that doesn't sound like a lot, you're right. You should think of implicit egotism as a tiny invisible nudge. It won't shape what everyone does all the time, but it does shape what some people do some of the time. It's when you multiply these small effects over hundreds of millions of people that you start to see lots of examples.
Brett says that if you really love your birthday, the effect gets even larger. Our operational definition of really loving your birthday was getting married on your birthday number. So if you got married on the 13th of the month, you were quite a bit more likely to marry another person who also had the number 13 as his birthday number. Again, Brett calls this an implicit bias for a reason.
You may not be consciously choosing things as important as your spouse or your profession or the place you call home based on arbitrary factors like your name or your birthday. He thinks the bias comes about simply because we like our names and our birthdays and have positive associations with them. And so you just associate your name with all the wonderful things that come along with that. And the best bit of evidence I have that I've never bothered to publish is there's one part of people's names they don't like that much, and that's their middle names.
You know, the joke about that is the sole purpose of a child's middle name is to know when he's really in trouble. And my additional kind of note, he might be a serial killer Sunday. Right? So the middle name is not nearly as loved as the first or the last name.
People feel very ambivalent about their middle name. There can be other reasons for ambivalence. Sometimes we dislike it when another person has the same birthday. If you were born on April 20th, you might hate the fact Hitler was born on that day too.
Brett finds that if a consumer product happens to have your name on it but is poorly built, you are more likely to hate that product. People dislike seeing something inferior in the world that has their name on it. As Brett and I were talking, I realized something a little uncomfortable that I myself had fallen prey to implicit egoism. You know, as you're talking right now, I'm realizing something about myself for the very first time.
There was a philosopher in India whose name was Shankara, my name. And he actually taught a philosophy that is known as Vedanta. And I've always been drawn to the fact that I find the philosophy of Vedanta to be very interesting and the fact that Shankara taught that philosophy, I thought was just charming. But now as I'm listening to you say this, I'm realizing that this could just be implicit ego.
I've read his work very well and it truly is wonderful. It's brilliant. So I think in this case, you make the objectively good decision. Yeah.
At the same time, it doesn't make you think though. Absolutely, yes. Has this ever happened to you, Brett? Do you ever think about yourself and how do you say that egoism is affecting you?
We're getting a little personal here, but I can't resist being a little bit personal. I would say that probably the most dramatic example is that my son Matthew, his last name is Poland, his mother's last name was Poland, my last name is Pelham. And I entered a relationship with her before I developed this theory, not after I developed the theory to validate the theory. So you're a Pelham and you got into a relationship with a woman named Poland.
Poland. And we are very different in most other ways. That's about as much as I'll say about that. Are you saying that the names played some kind of a role?
I have to think it did. We were from different backgrounds, different religions. I mean, we come from very different worlds. And yet I was very attracted to her.
Where she was attracted to me. Yeah. So I understand why you would call this charming. And I think if you do this work for a while, there is a certain smile that comes to your face as you look at these connections and you see you understand the choices that human beings make.
But I do think there's something disturbing about it because I think there is a very strong sense that I think most of us have. I have the sense, even though I've been covering the world of the unconscious mind for the last 10 years, I have the sense that my choices are deliberate choices that I've thought about them. I've actually making them intentional. I'm making them intentionally.
And the idea that you're coming in and telling me that these hidden factors have come in and changed how I think about myself, it is a disturbing idea. It is a little bit disturbing. And of course, most people do what you and I do, which is of course, that applies to the rest of all that I in particular would never fall prey to right implicit racial bias or implicit egotism. So most of us do tend to sort of separate ourselves from even our own findings.
But I've become in the past decade or so comfortable enough with the study that I have to admit that I really never know for sure exactly why I did something. I mean, sometimes I have a pretty good idea. But I certainly don't kid myself anymore to say that I even usually know why I do what I do. I mean, there's just too much research, much of which you documented and reported on that shows that biases were completely unaware of, nudge us, sometimes powerfully drive us in very particular directions.
So I think I just kind of let go of it. It was disturbing to me when I first began to study it, disturbing as well as delightful, and now it's become more delightful and less disturbing. So perhaps you're wondering, how does any of this matter? Who cares if people born on the 23rd of September marry those born on the 23rd of July?
Who cares if someone named Betsy Carpenter gravitates towards carpentry? Why does it matter if I prefer a philosopher who's name is similar to my own? It at least raises tough questions about the degree to which we have free will. So I think some people who have pretty negative reactions to this work are very threatened by it in the sense that it suggests that very important decisions have at least a little nudging influence based on things that you're completely unaware of.
So if people are more likely than they should be by chance to marry another person who happens to share their birthday number, that's not an objectively great reason to get married. You should get married because you share values, you're both Republicans, you're both right at Marxist. But learning that these subtle little influences can affect what you do, apparently to some people, I find it delightful, but some people find it pretty threatening. I don't think that it proves that there's no such things free will, but to me it does suggest that we don't always have free will.
Sometimes we make a decision for one reason that we told ourselves when really the more powerful underlying reason is something we could have never put our fingers on. And this isn't just a matter of being drawn to someone who shares your birthday. In general, we tend to refer things to people who have something to do with us, and that can be a big problem. Absolutely, I do a little bit of research on social justice, and that's one of the things that concerns me most is that we tend to focus on people who are more like us, who speak our language, who speak our idiom, who look like us, who worship like us, and we pay much less attention, sadly to the problems of people who don't.
On the other hand, I think this finding like any finding in psychology or behavioral economics can be used for good or evil, and the way it works and what can be used for good or bad. And so a great example that I perceive as at least a cousin of implicit egotism is a study I think was done by Elliot Smith and colleagues about 10 years ago. He looked at implicit racial bias, and he looked at implicit racial bias as a function of whether a person from a different ethnic group, I think he had whites and African Americans, for example, had simply given you a gentle, friendly touch on the shoulder. And if they had given you a friendly, gentle, pillow, how are you touched, that reduced their implicit racial bias.
So to me, when another person becomes a part of you in a very tiny way, you play in Trimmy Elbascoma with this person and you didn't like his group, but now that you meet him and he's on your team, suddenly he becomes a part of you, his group becomes a part of you, and your stereotypes get softened and diminished a little bit. When we come back, we're going to look at how the narcissist effect shapes another important part of your life. If you can fall in love with your name or your birthday, can't you also fall in love with your own ideas, your own work? Of course you can.
Researchers call this the IKEA effect. We come to overvalue the things that we have created ourselves. We also look at the implications that can have for things much bigger and much more complicated than Swedish furniture. Stay with us.
Create it ourselves. The way we usually think about IKEA is that IKEA gives you good furniture for low costs because they offload lots of the cost onto their consumer's assembly costs. But in fact, we're in a sense challenging that idea and saying there's actually psychological benefit behind this. That actually people might end up liking the furniture more because they built it.
And so it's not so much a cost but a benefit that they get to build their own furniture. Daniel and his co-authors did a series of experiments to test the hypothesis. They brought volunteers into the lab and gave them either a LEGO car preassembled or gave them Legos and instructions and told the participants to build a car themselves. Then they asked the volunteers, how much would you pay to keep your LEGO car?
And what we find is that the people who build their own Legos, not only are willing to pay more to keep their assembled Legos, but also when we ask them how proud they are of their own creations, they tend to be proud of their Legos. In mind you, these are Legos that are designed to 5 to 7-year-olds, but nonetheless it seems to be some competency and some pride associated with one's creation, even for basic things as building Legos. The researchers replicated the study using other products like IKEA furniture and the effect was the same. People who spent time and effort building something felt proud of what they built, fell in love with it, and were willing to pay lots of money to keep the things they built.
From the perspective of a rational economist, this doesn't make much sense. The students might be willing to pay twice as much money to buy the exact same LEGO car if they just finished building that LEGO car, then if the LEGO car was given to them rebuilt. So why might people value something more after building it themselves compared to buying the same product made by someone else for half the cost? Our hypothesis was that people tend to use products to signal value identities to both themselves and to others.
And we know that identity that people really care about is showing that they're competent in sort of one of the basics of human motivation. And so we hypothesize that people use self-made products as a way to signal competence to both themselves and to others. Having just built a table or having just built a bookcase, that bookcase has completed products, acts in the sense of a badge of my own personal competence. I completed it if I know I'm a competent person.
And more I can display this product and signal that identity is competent identity to others. And so we hypothesize that it was these feelings of competence associated with the products that led to their increasing valuation. To test the theory that people's feelings of competence was behind the idea of fact, the researchers had some participants think about other qualities they might value in themselves besides competence, things like honesty or intelligence or humor. Basically the idea was, if we make it less important for people to demonstrate competence, do they still overvalue their own creations?
So we found that the gift effect disappeared when we did death manipulation. So once competence wasn't that important to people, people are participants no longer seem to get much value in creating their own products, against suggesting that the reason why we tend to like our own creations is because we use them as a way to signal competence both to ourselves and to others. Here's the flip side of that coin. You can make the IKEA effects stronger by getting people to question their competence.
In one experiment, Daniel and his colleagues gave participants math problems to solve before asking them to build an IKEA project. If the problems were difficult, lots of people failed to solve them. Now, volunteers became much more likely to want to demonstrate their competence through the IKEA building project. The participants who at least temporarily had their sense of competence threatened to have got the very difficult math questions tended to be more willing to build their own products.
So when we surveyed them and asked, would you prefer to have an IKEA product that comes pre-built or the exact same product that comes unbuilt and you would build it yourself, those who got difficult math problems and were feeling someone incompetent at the time seemed more willing, they were much more likely to want to build a product themselves. And therefore, in a sense, restore their sense of competence through this activity. I mean, give me the numbers here. I mean, was this a big effect?
Was this a small effect? I mean, what happens when people feel bad compared to when they don't feel that? So what we found is that about a third of the people wanted to build the IKEA bookshelf in the control condition when they weren't made to feel bad. And this number went up to about 60% when they were made to feel bad.
So significantly, larger numbers of people wanted to do this. The IKEA effect and implicit egotism might seem at first blush to be interesting and amusing, but not terribly significant. But the more I thought about this, the more I saw the potential implications. Just as we can be drawn to those who have the same birthday as us or the same name as us, we might also be more inclined to help people who look like us, or sound like us, or live near us.
Let's say you're a Congress person who's drafted a particular piece of legislation. Your commitment to that bill might outweigh its importance to the public. Or let's say you're a president who starts a war. After years of investing your time and effort to prosecute that war, you may find it difficult to accept evidence that you made a mistake.
It's fine to gaze lovingly in the mirror and to feel invested in our own ideas. But like Narcissus discovered himself, falling in love with our own reflection can come in great peril. This episode was produced by Maggie Penman. Our team includes Tara Boyle, Jenny Schmidt, Part Shaw, Rayna Cohen, Laura Quirrell, and Thomas Liu.
Our unsung hero this week is Andy Huther. Andy is the audio engineer for podcasting at NPR. He's always willing to pitch into help. When we have questions about sound design or the right microphone to use, or how to make voices sound good in the studio, Andy always has good advice.
Thanks so much Andy. If you like this episode, please be sure to share it with a friend. If you don't know how to subscribe to Hidden Brain, please show them. I'm Shankar Vedantam and this is NPR.