Men, how do you keep the passion alive in your marriage? Surprise her with roses? Moonlight walks on the beach?

Well,we have a sure-fire, backed-by-science solution for you that won't cost a dime nor get sand in your shoes.

Puppies! Pictures of puppies, to be exact, although bunnies will work, too.

A team of researchers at Florida State University has determined thatpictures of cute animals, used as an intervention focused upon changing someone's thoughts about their spouse – as opposed to an intervention that targets their behavior – improves the quality of the relationship.

“One ultimate source of our feelings about our relationships can be reduced to how we associate our partners with positive affect, and those associations can come from our partners but also from unrelated things, like puppies and bunnies,” explained lead author James K. McNulty.

Here's what McNulty's team did: They rounded up 144 married couples, all under the age of 40 and married for less than 5 years. The average age of participants was 28 years old, and around 40 percent of the couples had children. To establish a baseline, at the start of the study, the couples were asked to complete a series of measures of relationship satisfaction.

A few days later, the spouses came to the lab to complete a measure of their immediate, automatic attitudes toward their partner.

Next, every three days for six weeks, each spouse was asked to individually view a brief stream of images. The stream contained embedded pictures of their partner. Those in the test group always saw the partner’s face paired with positive stimuli, such as a puppy or the word “wonderful,” while those in the control group saw their partner’s face matched to neutral stimuli, such as a button.

Along the way the couples were asked to complete implicit measures of attitude towards their partner, every 2 weeks for 8 weeks.

McNulty's thesis proved correct: Participants who were exposed to positive images paired with their partner’s face showed more positive automatic reactions to their partner over the course of the intervention compared with those who saw neutral pairings.

“I was actually a little surprised that it worked,” McNulty said. “All the theory I reviewed on evaluative conditioning suggested it should, but existing theories of relationships, and just the idea that something so simple and unrelated to marriage could affect how people feel about their marriage, made me skeptical.”

McNulty's team was quick to clarify that they are not arguing that behavior in a relationship is irrelevant to marital satisfaction. (That is, if your spouse catches you cheating, showing him or her a picture of a cute Cocker Spaniel likely won't cut it.) But a briefintervention focused on automatic attitudes could be useful as one aspect of marriage counseling or as a resource for couples in difficult long-distance situations, such as soldiers.

And this may be the best part, right here:

“The research was actually prompted by a grant from the Department of Defense – I was asked to conceptualize and test a brief way to help married couples cope with the stress of separation and deployment,” McNulty said. “We would really like to develop a procedure that could help soldiers and other people in situations that are challenging for relationships.”

The study has been published in Psychological Science.