An Equation That Predicts Happiness

Let’s talk about that age-old question: What is happiness?

Ben Franklin said it’s wine (or beer, in the more well-known version of the quote). Peanuts creator Charles Schultz said it’s a warm puppy; his brainchild Charlie Brown, in a not-so-subtle slight to Snoopy, said it’s actually learning to whistle. Pharrell Williams, weirdly, said it’s a room without a roof. Research has said it’s ordinary experiences, or having kids, or maybe just genetics. The U.S. founding fathers didn’t specify, but they promised we’d all have the right to go after it. We used to think it’s something money can’t buy, though even that has been cast into doubt.

Clearly, there’s still some confusion.

Now researchers think they’ve found another answer, at least for the short term: Happiness is the management of expectations. In a study published earlier this week in the Proceedings of the National Academy of Sciences, a team of British neuroscientists created an equation that they say accurately predicted the short-term happiness of more than 18,000 people by comparing their expectations of an event to its real-life outcomes.

Here’s what that looks like:

And, in case the sight of alarmingly long equations doesn’t make you happy, here’s what it boils down to: Happiness “doesn’t depend on how things are going,” says lead study author Robb Rutledge of University College London. “It depends on whether things are going better or worse than you had expected they would.”

In the first leg of the study, the researchers developed the equation by having a group of volunteers play decision-making games, rewarding certain choices with small amounts of money. Every few rounds, participants were asked to rate their happiness on a sliding scale, while their neurological responses to the rewards were measured with MRI scans.

In the second leg, the team tested the equation on a larger audience by turning the decision-making task into a smartphone game, drawing players by the thousands. The results were as their model had predicted: When players expected a reward, they were less happy to receive it than if they hadn’t expected anything at all.

That’s not to say that the equation has completely cracked the code to eternal happiness. First of all, it measures only immediate reward, not long-term satisfaction. When all the short-term spikes and dips are accounted for, people still have a baseline happiness point where they tend to stay over the course of a lifetime, Rutledge says: “As good things happen, your happiness will go up. As bad things happen, your happiness will go down. But over time, you’ll kind of drift back.” Even lottery winners, one study found, will return to their ordinary happiness levels soon after the rush of winning subsides; what was a source of joy eventually becomes the new normal.

And second, keeping expectations perpetually low doesn’t necessarily lead to a perpetual state of delight; gleeful anticipation can have its own benefits. “You’ll be happier if you have low expectations when you’re at the outcome,” Rutledge explains, “but before you get to the outcome, you’ll be happier if you have higher expectations.” If you want to extract the maximum amount of pleasure out of a beach vacation, for example, fantasize about sunny skies up until the day you leave, and then pack an umbrella and a few board games.

But limitations aside, the happiness equation has implications that could reach beyond the lab or the smartphone. Governments have taken an active interest in figuring out what makes their citizens happy: Bhutan keeps tabs on its Gross National Happiness; the U.K. and Canada both have programs to measure “national well-being”; even the city of Santa Monica, California recently got in on the action.

And perhaps more importantly, the ability to predict happiness could lead to new discoveries in mental health research. Rutledge and his team have already begun to study how their findings could apply to people suffering from mood disorders by looking at the brains and decision-making processes of patients with depression.

“Is there something different about how they respond to rewards? Is there something different about [their] expectations?” he says. “If we can quantify them and predict how they relate to other objective things in the world, hopefully we can understand these disorders a little bit better.”

No matter how you define it, that would be a happy consequence.