Snap out of it! That daydream you're having about eloping to the Bahamas with Johnny Depp or Angelina Jolie is leaching away your happiness. In a new global study, researchers used iPhones to gauge the mental state of more than 2000 volunteers several times a day—even when they were having sex. The results indicate that, if you want to stay cheerful, you're better off focusing on the present, no matter how unpleasant it is.
The human mind is remarkably good at straying from the moment. That ability allows us to remember the past, plan for the future, and "even imagine things that never occur at all," says Matthew Killingsworth, a doctoral student in psychology at Harvard University. "As a scientist, it's something I do all the time."
But is daydreaming good for us?
That's a tough question to answer, says Killingsworth. To find out, scientists must survey subjects several times a day to record their mood and activities at that exact moment. "People are quite good at telling you how happy they are right now," he says, "but less at telling you how happy they were last week." In the past, researchers have used buzzing pagers, which reminded volunteers to write in a diary, or they bought their subjects expensive mobile devices like Palm Pilots. Both methods are hard to scale up. So Killingsworth, a former product developer at a Cambridge, Massachusetts, software company, took advantage of something thousands of people already have and use all the time: iPhones.
In 2009, Killingsworth and Harvard psychologist Daniel Gilbert, with the help of a friend who is a software engineer, launched a study on a Web site called Track Your Happiness.org . After answering basic questions about their age, location, and general satisfaction with their job, marriage, or car, iPhone owners could sign up to receive one or more text messages a day. These texts nudged them to visit an online survey to report how happy they were feeling and pick from 22 different choices, including shopping, watching television, or working, to describe what they were doing right then. Subjects also recorded whether they were thinking about that activity or about something else that was pleasant, neutral, or unpleasant.
Although the study was only advertised on Killingsworth's Web site, he soon had nearly 5000 subjects from 83 different countries sending in data several times a day. The volunteers were surprisingly diligent, responding, on average, to about 83 percent of the nudges. Even during activities such as making love, subjects logged on to report what they were doing. "Hopefully we're not disrupting people's sex lives," jokes Killingsworth, "because yes indeed we did get responses."
When the researchers analyzed the experiences of a subset of 2250 adults, about three-quarters of them from the United States, the first thing they noticed was just how often people weren't thinking about what they were doing. Over all, subjects' minds were wandering about 47% of the time, the duo reports  online today in Science. Only during sex did mind-wandering occur less than 30% of the time.
The daydreaming was not good for people's moods: Volunteers were unhappier when their thoughts were elsewhere. Statistical tests showed that mind-wandering earlier in the day correlated with a poorer mood later in the day, but not vice versa, suggesting that unhappiness with their current activity wasn't prompting people to mentally escape. Instead, their wandering minds were the cause of their gloom. Mental drifting was a downer for subjects during even the dullest activities, like cleaning, the researchers found. "I'm sure there are some situations where mind-wandering can be helpful," says Killingsworth. But based on these results, those "are probably pretty rare."
The findings "challenge the foundations of psychology," says Lisa Feldman Barrett, a psychologist and neuroscientist at Northeastern University in Boston, who pioneered data gathering with Palm Pilots. Psychologists assume that the mind responds to a stimulus out in the world, but in this study, "it almost looks like the stimulus is irrelevant."
Still, says Barrett, the study has limitations. For one, not everyone can afford to own an iPhone, so the study sample may not be representative of the population. And as to whether mind-wandering was really the cause of subjects' unhappiness, Barrett would like to see stronger evidence. Killingsworth's statistical analysis "is a good start, but not a sufficient answer," she says. He showed a cause-and-effect relationship for samples that were several hours apart from each other, Barrett notes, but that says little about "shifts in consciousness [that] occur on the order of milliseconds."