Scientists scrutinize happiness research

We all want to be happy — and for decades, psychologists have tried to figure out how we might achieve that blissful state. The field’s many surveys and experiments have pointed to a variety of approaches, from giving stuff away to quitting Facebook to forcing one’s face into a toothy grin.

But psychology has undergone serious upheaval over the last decade, as researchers realized that many studies were unreliable and unrepeatable. That has led to a closer scrutiny of psychological research methods, with the study of happiness no exception. So — what really makes us happy? Under today’s more careful microscope, some routes to happiness seem to hold up, while others appear not to, or have yet to re-prove themselves. Here’s what we know so far, and what remains to be reassessed, according to a new analysis in the Annual Review of Psychology.

Put on a happy face

One long-standing hypothesis is that smiling makes you feel happier. In a classic 1988 study, researchers asked 92 Illinois undergraduates to hold a felt tip pen in their mouth either with their teeth, forcing an unnatural grin, or with their lips, making them pout. The students then looked at four examples of The Far Side comics. On average, those with the forced smiles found the one-panel comics slightly funnier than those with the forced pouts.

But when 17 different research labs got together to retest the pen-clench smile’s effects on 1,894 new participants, the finding failed to hold up, the researchers reported in 2016.

The repetition study was part of a broader effort to counter psychology’s reproducibility crisis, which in part has been attributed to the variety of ways in which researchers could examine and reanalyze their data until they arrived at publishable results. “It’s kind of like shooting a bunch of arrows at the wall and drawing the bullseye on after,” says Elizabeth Dunn, a social psychologist at the University of British Columbia in Vancouver and coauthor of the new Annual Review of Psychology paper.

One solution has been for scientists to publicly declare, or preregister, their analysis plans before they conduct their experiments. In other words, they draw the bullseye first. Dunn and her graduate student, Dunigan Folk, homed in on such preregistered studies in their analysis, which narrowed the vast field of happiness research to just 48 published papers. Even that small number is encouraging, says Brian Nosek, a psychologist at the University of Virginia in Charlottesville and executive director of the Center for Open Science, which aims to improve research reproducibility. “I was actually surprised that there were as many papers that qualified,” he says. “That really demonstrates that this area of research has adopted a lot of these new rigor-enhancing practices.”

Preregistration alone doesn’t guarantee that results will be correct, nor does it solve all of psychology’s reproducibility problems. Quality studies also require sound methods and large and diverse sets of participants, for example. And indeed, most of the papers reviewed were high quality in those features beyond just preregistration, Dunn says. Even under the regimen of renewed scrutiny, some of the paths to happiness held up, the researchers found — including practicing gratitude, acting sociable and spending money on other people.

Take gratitude. In one of the recent studies, researchers asked hundreds of parents to either write about how they spent their week, or pen a gratitude letter to someone they knew. Expressing gratitude resulted in more positive moods. In another recent study, scientists asked more than 900 undergraduates to express gratitude in letters, texts or social media, or to list their daily activities. Those in the gratitude group scored as happier and more satisfied with their lives the following day. In both cases, it’s unclear how long these effects would persist.

Three different preregistered studies pointed to sociability as beneficial. In one, scientists assigned 71 adults to act extroverted — “bold, talkative, outgoing, active and assertive” — for a week, and another 76 to be “unassuming, sensitive, calm, modest and quiet.” Participants in the extroverted condition reported better moods during the study week, though the benefits were less for those who were naturally introverted.

And surprise! Smiling to promote happiness was also supported by new, preregistered research — once scientists switched to more natural grins. About two dozen labs from 19 different countries worked together to test the instruction to grip a pen in the teeth or to mimic the expression of a smiling person in nearly 4,000 subjects. The pen clenching still didn’t work, but people who were told to copy a smile did report better moods. Remarkably, this was true even if the subjects didn’t believe it would work, another team reported in 2023.

Researchers have also found that external agencies can promote people’s happiness. Giving people cash promoted life satisfaction, as did workplace interventions such as naps.

Dunn cautions, however, that participation in preregistered studies tends to yield small effects on happiness overall, in part because scientists can’t massage the data to get bigger numbers. If the interventions were a diet program, she says, users might drop about four pounds.

Nice ideas, poor results

Other well-known happiness approaches haven’t measured up to Dunn and Folk’s standards — at least, not yet. The researchers didn’t find clear evidence of benefits for volunteering, performing random acts of kindness or meditation. For example, a recent, preregistered study asked participants to perform acts of kindness for others, or for themselves, or simply to list what they did each day. Being kind to others over a four-week period made no difference to well-being.

Dunn and Folk didn’t find any preregistered studies at all on exercising or spending time in nature, two oft-recommended strategies. That doesn’t mean those strategies don’t or can’t work, Dunn says — just that as the preregistered landscape now stands, research hasn’t weighed in. The pair considered only two preregistered studies on meditation, and did not include meditation research on people with diagnosed mental health problems.

Such rigor is admirable, but it also means one can miss things, says Simon Goldberg, a psychologist at the University of Wisconsin-Madison. He studies the effects of meditation, including research among people who have psychological problems such as depression and anxiety. He noted that because of Dunn and Folk’s strict criteria, they omitted hundreds of studies on meditation’s benefits. “It’s, in the spirit of rigor, throwing lots of babies out with the bathwater,” he says. “It’s really very obvious that meditation training reduces symptoms of anxiety and depression.”

Dunn agrees that the review only covered the tip of the iceberg of happiness research. But that tip should expand as more psychologists preregister their science as part of what some call a renaissance in the field. As Dunn and Folk conclude, “happiness research stands on the brink of an exciting new era.”

This article originally appeared in Knowable Magazine, a nonprofit publication dedicated to making scientific knowledge accessible to all. Sign up for Knowable Magazine’s newsletter.