The Science of Love

Posted on May 3, 2024

Love, love, love — all psychology Professor Sara Algoe needs is love. And she sees plenty of it.

For the past 14 years, this self-professed people watcher has invited thousands of couples — old, young, Black, white, straight, gay — to her Emotions and Social Interactions Relationships Lab.

There on the third floor of Davie Hall, lovebirds cozy into a plush sofa in a windowless room. During experiments designed to spark playful warm feelings, their every word, smile, chuckle and caress is captured by video cameras hidden inside two wall-mounted black globes.

Working with her is a team of postdoc, graduate and undergraduate assistants, whom Algoe, an expert on gratitude and its effects on well-being, said are “wonderful.” They scrutinize the recordings second-by-second to hunt for relationship clues. Using precise behavioral coding techniques, they tally how often each couple interacted, such as a touch, a laugh and an expression of gratitude.

“I regularly think, gosh, if only other people could see what I see. It’s such a joy. It’s such a privilege, too. I love it,” said Algoe, her face aglow with good cheer.

No wonder. She is one of the nation’s leading experts on love and happiness. Her views on relationships — and how to improve them — often appear in media outlets that range from The Wall Street Journal and the Harvard Business Review to lifestyle media company PopSugar and CBS News.

“It seems like the most effective way to help the world is through helping people understand each other better and get along better with one another,” she said. “I’d love to try to bottle the moments of love, shared laughter and gratitude we see in our data.”

Her goal? To find scientific proof that gestures of love strengthen relationships and boost partners’ physical and psychological health, just as millions of mothers and every major religion have insisted from time immemorial.

“We try to do our studies in ways that resonate with people, so we can demonstrate the value of these behaviors for real relationships in people’s everyday lives,” Algoe said. “It’s one thing to have self-reported questionnaires, but it’s different when you can say, ‘Oh, yeah, we predicted kissing in my lab from moments we observed.’ ”

Algoe said one common finding recurs in her experiments: Basic expressions of thanks have a powerful impact.

She noticed many couples often laughed at the same time and wondered whether something about their relationships could be deduced from that. After systematically reviewing videos to count every shared laugh and comparing those results with other data, Algoe concluded that couples who often laugh together report greater closeness than those who share laughs less often.

“I call it ‘the mind meld,’ ” she said. “When you’re laughing with another person, you think you see the world the same way. It’s the marker of a high-quality relationship.”

Algoe once told an interviewer that her “working definition” of love was “an other-focused positive feeling that really blurs the boundaries between the self and the other person. … A state where you think of yourself as really merged.”

She defines gratitude as “an emotion we can experience when someone else does something nice for us.” Expressing it creates more than mere psychological effects; it can lower blood pressure and help the heart function better, she said.

That conclusion came as the result of her study, which asked two teammates to draft a presentation on a tight deadline. When one person expressed gratitude to the other before getting started, on average the cardiovascular functions of both improved. On the other hand, if a teammate expressed no gratitude, both members had a significant threat response while working together. A similar study of couples found those who spent more time with their partner in the past day had lower levels of C-reactive protein in their blood, which signified less inflammation and better heart health.

Gratitude has ripple effects, too. Her test subjects viewed a person recording a romantic message to an unseen partner. Algoe found they concluded the other party was a good person, even though they knew nothing about the person.

“If relationships are one of the best predictors of mental and physical health, everyday life satisfaction and longevity, then just like understanding the air we need to breathe, why shouldn’t we dig into finding out exactly what is going on in relationships?”

— Sara Algoe

Even a single expression of gratitude can create what she calls an “upward spiral” of positive effects. For this study she had one member of a couple complete a five-minute, self-guided online exercise, in which the partner would make a plan to express gratitude. Over five weeks, Algoe found the couples increased their time together by an average of 68 minutes per day compared with a control group whose members did no planning.

Algoe also regularly tests for gender differences, but she said, “We never find them. The way I interpret it is everybody wants to be valued.”

Fellow UNC psychology Professor Barbara Fredrickson and her research on positive emotions inspired Algoe early in her career. Her research into positive psychology found that experiencing pleasant emotions fortifies a person’s well-being and health. “Barb did pioneering work,” Algoe said. “She opened the floodgates.”

Until recently little research had been conducted in her field partly because scholars, politicians and the public in general had contempt for those who plumbed love’s scientific underpinnings.

The late Sen. William Proxmire won national attention in the 1970s for his Golden Fleece Awards, in which he decried what he deemed government spending on questionable projects. He upset the career of University of Wisconsin scholar Elaine Hatfield in 1975, when he ridiculed her love and desire research, according to Algoe. Other scholars, a Catholic bishop and some members of the public told Hatfield she was wasting her time on her research. When The Chicago Daily News asked readers who was right — Proxmire or Hatfield — more than 87 percent agreed with the senator.

Times have changed. “I haven’t had any pushback,” Algoe said. Her work is supported by the Templeton Foundation, not the government.

When asked why anyone should bother proving scientifically the power of love, something that prophets and poets have always known, the unflappable Algoe has a ready answer.

“Thank you,” she said, ever conscious of the power of gratitude. Then she kindly insists, “Put this as the centerpiece of your piece. Nobody would question why we need to understand what’s in the air we breathe. All kinds of scholars think these behaviors are the essence of the best relationships.

“But we don’t actually know that’s true. If relationships are one of the best predictors of mental and physical health, everyday life satisfaction and longevity, then just like understanding the air we need to breathe, why shouldn’t we dig into finding out exactly what is going on in relationships?”

To help other scholars further their study of human interactions, Algoe created The Love Consortium. It lets international researchers post their datasets for others to use. When asked why a prominent scientist might share his or her hard-earned work, Algoe exclaims, “Oh, scientific discovery. Scientific discovery. That’s one thing. Seriously, the other is giving back.”

— George Spencer