Daniel Gilbert, PhD, didn’t intend to be a psychologist. After dropping out of high school, he decided to become a science fiction writer. He began writing and publishing stories, eventually honing his craft by taking a creative writing class at the local community college in Denver.

“When I got there, creative writing was closed but psychology was open,” says Gilbert. “It had been a long bus ride, so I said, ‘OK, sign me up.’ That was the beginning.”

Today Gilbert is a psychology professor at Harvard. His book “Stumbling on Happiness” (Knopf, 2006) became a New York Times best-seller. And a hit television series called “This Emotional Life,” which Gilbert co-wrote and hosted, aired on PBS in January and attracted more than 10 million viewers. Gilbert is intent on spreading his message — that most of us do a terrible job of predicting what will make us happy or unhappy in the future.

The Monitor spoke with Gilbert about what makes him — and us — happy.

How did you first get interested in happiness?

About a decade into my career, I was having lunch with a friend. It had been a particularly bad year for both of us — lots of problems with friends and family and the deaths of people close by. What struck us was that we were surprisingly OK. That either meant we were heartless bastards, or it meant that we were bad at predicting how these things would impact us. Surely, if you had asked us to predict a year before, we both would have said, “I won’t be able to get out of bed in the morning.” We were not only out of bed, but we were doing our jobs and living our lives and having a fairly good time of it. So we asked each other the question, “Do people know what will make them happy?” and neither of us knew the answer.

After lunch, I went back to my office and started looking through the journals to see what I could find. I found nothing. My collaborator Tim Wilson and I decided we would try one experiment and just see how it worked out. We showed some “forecasters” a negative personality description and asked them to predict how they’d feel if a psychological test revealed that it was an accurate characterization of them. They predicted that they’d be devastated. We then gave some “experiencers” a bogus personality test, gave them the negative personality feedback that we’d shown the forecasters, and asked them how they felt. The experiencers didn’t report feeling nearly as bad as the forecasters thought they would. One experiment led to another and then another. Doing experiments that work is like eating potato chips: Once you get going, it’s hard to stop. So here Tim and I are, 15 years later, eating out of the same bag of chips.

Did your findings change your personal as well as professional life?

Absolutely! We’ve done many studies showing that people are far more resilient than they themselves predict. These findings have made me less fearful in my personal life. I now recognize that if things go badly, I will probably bounce back and be all right. Therefore, I take more risks and I don’t worry as much about what might go wrong.

Certain findings have had a particularly big impact on me. For example, a study I did with Jane Ebert about 10 years ago showed that people are happier with decisions when they can’t change their minds about them.

As soon as those data came in, I told a colleague about them, and he said, “That’s the essential difference between being married and living together. When you’re married, it’s pretty darn hard to just change your mind.” A lightbulb went off and I decided to propose to my girlfriend. Now we’re married, and I do indeed love my wife more than I loved my girlfriend, even though they are the same woman. One reason is that I’ve made a commitment that’s hard to get out of, and as a result I find ways to make my choice the right one. So yes, my research does change my life, and I’m wearing a wedding ring to prove it.

Our society is suddenly awash in books about happiness. Why?

Happiness is the ultimate goal of virtually all the decisions we make. In one form or another, the measure of a good decision is whether it brings well-being, pleasure, happiness, joy, contentment — pick your favorite. It’s the primary motivator of human behavior.

I’m standing here looking at a shelf of books, every one of which has the word “happiness” in the title, all of which have been published in the last five years. So why the sudden surge in publication? It isn’t because happiness has suddenly become important to people, but rather, it is because science has finally started giving them information about it.

People have always wanted to know where happiness lies, and they’ve taken their cues from grandmothers, rabbis, mystics, priests, philosophers and other people who may well know a lot about happiness but who don’t have any data to back it up. The same techniques we use to discover what causes lung cancer or global warming can be used to discover what causes happiness. Economists, neuroscientists and especially psychologists are now telling people something they really want to know.

You do so many different things: teaching, research, writing, television. What makes you happiest?

What makes me happiest isn’t any of the things you listed. Don’t get me wrong, I really like all those things. I loved writing “Stumbling on Happiness.” I loved making a television show because I got to be a student again and learn about a whole new industry. I love teaching introductory psychology. I love working with Tim and my graduate students on research. But none of these is my greatest source of happiness because my greatest source of happiness is my family and friends — and especially my unbelievably adorable granddaughters. Like most people, my greatest source of happiness is social. Unlike most people, I know it.

What do you plan to talk about at this year’s APA convention?

It’s probably fair to say that I will talk about how and how well people can predict what will make them happy, what some of the sources of our mispredictions might be, and what we can do about it.

What’s next for you?

If you had asked me that question at any time in the past, I would have answered it incorrectly, so I’ve stopped trying to answer it. Ten years ago, I could not have told you that I was going to write “Stumbling on Happiness.” Five years ago, I could not have told you that I was going to make “This Emotional Life.” And I don’t think it’s because I’m a particularly bad predictor of what’s next for me.

It’s just that the most interesting things in life come looking for you rather than the other way around. A great book is one that begs you to write it. A great film is one that invites you to do it. And when it comes to research, I won’t know what experiment I’m going to be doing next week until I know what this week’s experiments revealed, or what interesting idea came into one of my collaborator’s heads, or what weird thing I will see in the shopping mall on Saturday.

I’m happy to not be able to predict what’s going to happen next and to just experience it when it does. So far it has always been something delightful and delicious.

Rebecca A. Clay is a writer in Washington, D.C.