Global Links

For Alumni and Friends of The State University of New Jersey

Bookmark and Share

Flower Power

Researchers Jeannette Haviland-Jones and husband Terry McGuire explain why flowers may be potent mood elevators.

Jeannette Haviland-Jones and Terry McGuire
Researchers Jeannette Haviland-Jones and her husband, Terry McGuire, offer convincing evidence that flowers may be potent mood elevators.  Photography by Nick Romanenko

If spring brings a lightness in your step, you might want to thank the flowers. Research by Jeannette Haviland-Jones, professor of psychology, and her husband, Terry McGuire, professor of genetics, both at the School of Arts and Sciences, offers convincing evidence that flowers may be potent mood elevators.

In the first of several double-blind studies performed in 2005, Haviland-Jones and her team presented participants with one of three gifts—a decorative candle, a fruit basket, and a floral bouquet—­supposedly as a thank-you for taking part in a study on mood. The delivery people were really out to measure the recipients’ facial expressions in response to the gifts; the research was then analyzed and coded by Haviland-Jones in her Human Emotions Lab at Rutgers. In every case, the recipients responded to the flowers with what is known as the Duchenne smile—a heartfelt “true smile” involving the mouth, cheeks, and eyes; neither the candle nor the fruit elicited that kind of across-­the-board positive response. And three days later, the flower recipients were still feeling happier than their cohorts in the study. Clearly, something about flowers was uniquely moving them, and Haviland-Jones didn’t think it was simply that “we’re socialized to like flowers.”

For a possible explanation, she turned to her husband, whose work in evolutionary biology offered a different vantage point. “It began to dawn on me,” McGuire says, “that we were really into coevolution”—whereby two (or more) species evolve in response to changes in the other. On this evolutionary two-way street, we may have offered the flowers a way to be fruitful and multiply (by cultivating them in our gardens rather than tossing them onto the Bronze Age compost pile). And they offered us something that, until recently, wasn’t considered necessary for survival: pleasure.

— Leslie Garisto Pfaff

Rutgers Magazine: Were you surprised by the results of your study?

Jeannette Haviland-Jones: I was shocked. When I saw that every person who got the flowers responded with the Duchenne smile, I thought, No, this doesn’t happen. In the emotions lab, you never get a 100 percent response unless you’re dropping a snake on people, which gives you a nice 100 percent fear response. But, happy? No.

RM: Why would something that merely makes us feel good, like flowers, afford an evolutionary edge?

JH-J: Somebody asked me, “Are you saying that flowers are the pets of the plant world?” And that’s probably true: flowers, like pets, help reduce stress. And, thanks to the new field of positive psychology, there’s more evidence that positive emotion is healing and enhances reproductive fitness.

RM: What is it about flowers that makes us so happy?

JH-J: One of the original theories, from [biologist and environmentalist] E.O. Wilson, was that flowers were a marker for fruit, and that’s why people liked them. But people actually don’t prefer the flowers that lead to fruit, so it seems like a weak argument. It may be that plants use a number of roads. One could be odor, which I think is particularly likely. Color is another good possibil­ity. And there is some research showing that we’re drawn to symmetrical shapes and patterns.
Not all flowers are symmetrical, but most are.

RM: How did we coevolve with flowers?

Terry McGuire: The flowers we didn’t pull up from our food gardens were the ones that made us feel good in some way. We moved from tolerating them to liking them to picking out the ones we really liked and planting them and moving them around.

RM: Do you keep flowers in your own offices?

TM: I grow some incredible, dinner plate-size dahlias. And when they come in, I share them all over the building.

RM: And do you get that Duchenne smile?

TM: Oh, yeah. You bet. •