So, people want a lot of things out of life, but I think, more than anything else, they want happiness. Aristotle called happiness "the chief good," the end towards which all other things aim. According to this view, the reason we want a big house or a nice car or a good job isn't that these things are intrinsically valuable. It's that we expect them to bring us happiness.

Now in the last 50 years, we Americans have gotten a lot of the things that we want. We're richer. We live longer. We have access to technology that would have seemed like science fiction just a few years ago. The paradox of happiness is that even though the objective conditions of our lives have improved dramatically, we haven't actually gotten any happier.

Maybe because these conventional notions of progress haven't delivered big benefits in terms of happiness, there's been an increased interest in recent years in happiness itself. People have been debating the causes of happiness for a really long time, in fact for thousands of years, but it seems like many of those debates remain unresolved. Well, as with many other domains in life, I think the scientific method has the potential to answer this question. In fact, in the last few years, there's been an explosion in research on happiness. For example, we've learned a lot about its demographics, how things like income and education, gender and marriage relate to it. But one of the puzzles this has revealed is that factors like these don't seem to have a particularly strong effect. Yes, it's better to make more money rather than less, or to graduate from college instead of dropping out, but the differences in happiness tend to be small.

Which leaves the question, what are the big causes of happiness? I think that's a question we haven't really answered yet, but I think something that has the potential to be an answer is that maybe happiness has an awful lot to do with the contents of our moment-to-moment experiences. It certainly seems that we're going about our lives, that what we're doing, who we're with, what we're thinking about, have a big influence on our happiness, and yet these are the very factors that have been very difficult, in fact almost impossible, for scientists to study.

A few years ago, I came up with a way to study people's happiness moment to moment as they're going about their daily lives on a massive scale all over the world, something we'd never been able to do before. Called trackyourhappiness.org, it uses the iPhone to monitor people's happiness in real time. How does this work? Basically, I send people signals at random points throughout the day, and then I ask them a bunch of questions about their moment-to-moment experience at the instant just before the signal. The idea is that, if we can watch how people's happiness goes up and down over the course of the day, minute to minute in some cases, and try to understand how what people are doing, who they're with, what they're thinking about, and all the other factors that describe our day, how those might relate to those changes in happiness, we might be able to discover some of the things that really have a big influence on happiness. We've been fortunate with this project to collect quite a lot of data, a lot more data of this kind than I think has ever been collected before, over 650,000 real-time reports from over 15,000 people. And it's not just a lot of people, it's a really diverse group, people from a wide range of ages, from 18 to late 80s, a wide range of incomes, education levels, people who are married, divorced, widowed, etc. They collectively represent every one of 86 occupational categories and hail from over 80 countries.

What I'd like to do with the rest of my time with you today is talk a little bit about one of the areas that we've been investigating, and that's mind-wandering. As human beings, we have this unique ability to have our minds stray away from the present. This guy is sitting here working on his computer, and yet he could be thinking about the vacation he had last month, wondering what he's going to have for dinner. Maybe he's worried that he's going bald. (Laughter) This ability to focus our attention on something other than the present is really amazing. It allows us to learn and plan and reason in ways that no other species of animal can. And yet it's not clear what the relationship is between our use of this ability and our happiness. You've probably heard people suggest that you should stay focused on the present. "Be here now," you've probably heard a hundred times. Maybe, to really be happy, we need to stay completely immersed and focused on our experience in the moment. Maybe these people are right. Maybe mind-wandering is a bad thing. On the other hand, when our minds wander, they're unconstrained. We can't change the physical reality in front of us, but we can go anywhere in our minds. Since we know people want to be happy, maybe when our minds wander, they're going to someplace happier than the place that they're leaving. It would make a lot of sense. In other words, maybe the pleasures of the mind allow us to increase our happiness with mind-wandering.

Well, since I'm a scientist, I'd like to try to resolve this debate with some data, and in particular I'd like to present some data to you from three questions that I ask with Track Your Happiness. Remember, this is from sort of moment-to-moment experience in people's real lives. There are three questions. The first one is a happiness question: How do you feel, on a scale ranging from very bad to very good? Second, an activity question: What are you doing, on a list of 22 different activities including things like eating and working and watching TV? And finally a mind-wandering question: Are you thinking about something other than what you're currently doing? People could say no -- in other words, I'm focused only on my task -- or yes -- I am thinking about something else -- and the topic of those thoughts are pleasant, neutral or unpleasant. Any of those yes responses are what we called mind-wandering.

So what did we find? This graph shows happiness on the vertical axis, and you can see that bar there representing how happy people are when they're focused on the present, when they're not mind-wandering. As it turns out, people are substantially less happy when their minds are wandering than when they're not. Now you might look at this result and say, okay, sure, on average people are less happy when they're mind-wandering, but surely when their minds are straying away from something that wasn't very enjoyable to begin with, at least then mind-wandering should be doing something good for us. Nope. As it turns out, people are less happy when they're mind-wandering no matter what they're doing. For example, people don't really like commuting to work very much. It's one of their least enjoyable activities, and yet they are substantially happier when they're focused only on their commute than when their mind is going off to something else. It's amazing.

So how could this be happening? I think part of the reason, a big part of the reason, is that when our minds wander, we often think about unpleasant things, and they are enormously less happy when they do that, our worries, our anxieties, our regrets, and yet even when people are thinking about something neutral, they're still considerably less happy than when they're not mind-wandering at all. Even when they're thinking about something they would describe as pleasant, they're actually just slightly less happy than when they aren't mind-wandering. If mind-wandering were a slot machine, it would be like having the chance to lose 50 dollars, 20 dollars or one dollar. Right? You'd never want to play.

So I've been talking about this, suggesting, perhaps, that mind-wandering causes unhappiness, but all I've really shown you is that these two things are correlated. It's possible that's the case, but it might also be the case that when people are unhappy, then they mind-wander. Maybe that's what's really going on. How could we ever disentangle these two possibilites? Well, one fact that we can take advantage of, I think a fact you'll all agree is true, is that time goes forward, not backward. Right? The cause has to come before the effect. We're lucky in this data we have many responses from each person, and so we can look and see, does mind-wandering tend to precede unhappiness, or does unhappiness tend to precede mind-wandering, to get some insight into the causal direction. As it turns out, there is a strong relationship between mind-wandering now and being unhappy a short time later, consistent with the idea that mind-wandering is causing people to be unhappy. In contrast, there's no relationship between being unhappy now and mind-wandering a short time later. In other words, mind-wandering very likely seems to be an actual cause, and not merely a consequence, of unhappiness.

A few minutes ago, I likened mind-wandering to a slot machine you'd never want to play. Well, how often do people's minds wander? Turns out, they wander a lot. In fact, really a lot. Forty-seven percent of the time, people are thinking about something other than what they're currently doing. How does that depend on what people are doing? This shows the rate of mind-wandering across 22 activities ranging from a high of 65 percent — when people are taking a shower, brushing their teeth, to 50 percent when they're working, to 40 percent when they're exercising, all the way down to this one short bar on the right that I think some of you are probably laughing at. Ten percent of the time people's minds are wandering when they're having sex. (Laughter) But there's something I think that's quite interesting in this graph, and that is, basically with one exception, no matter what people are doing, they're mind-wandering at least 30 percent of the time, which suggests, I think, that mind-wandering isn't just frequent, it's ubiquitous. It pervades basically everything that we do.

In my talk today, I've told you a little bit about mind-wandering, a variable that I think turns out to be fairly important in the equation for happiness. My hope is that over time, by tracking people's moment-to-moment happiness and their experiences in daily life, we'll be able to uncover a lot of important causes of happiness, and then in the end, a scientific understanding of happiness will help us create a future that's not only richer and healthier, but happier as well. Thank you.