PROVO — And you thought Windex was just for cleaning windows.

It turns out the lemon-scented cleaner is also useful in promoting selfless behavior and altruistic choices.

A study led by a BYU professor found that people who were asked to divide money or volunteer for charitable organizations were significantly more giving in a room recently spritzed with lemon-scented Windex than in a nonscented room.

But why lemon?

Previous research suggests that citrus smells are most commonly associated with cleanliness, said lead author Katie Liljenquist, an assistant professor in BYU's Marriott School of Management.

"It's something that's pretty universal," Liljenquist said. "We just wanted something that was very prototypical. We didn't want it to be too obtrusive."

So after two sprays of Windex into a room, participants were invited in and given $12. They were told it was the return on a $4 investment from an anonymous "partner" in another room.

The participants then had to decide if they would split the $12 with the investor or keep it all for themselves.

The people in lemon-scented room were much more fair and generous in returning money to their partners, Liljenquist explained, giving back an average just more than $5.

But in the room without a lingering lemon smell, the participants sent back an average of $2.81.

The next study asked participants how willing they would be to volunteer or donate money to Habitat for Humanity. Again, willingness went up due to Windex — 22 percent in the sprayed room compared with 6 percent in the other.

"At the end of the study, we'd always ask them, 'What other factors would explain the choices you made?' " Liljenquist said. "Nobody ever suspected the environment … that the room smelled clean."

The study, titled "The Smell of Virtue," was recently accepted for publication in Psychological Science.

"Smell has an incredibly important effect on certain behavior, even if (people are) not aware of it," said co-author Adam Galinsky, Kaplan professor of ethics and decision making at the Kellogg School of Management at Northwestern. "Smell determines what memories get activated in our mind. It can draw us back to childhood; it affects romantic attraction. Smell is an underappreciated regulator of people's behavior."

And, according to this study, the smell of cleanliness seems to trigger an "unconscious sense of morality," Liljenquist said.

However, promoting altruism may not be as easy as dousing every store, classroom and home with citrus, says study co-author Chenbo Zhong, a professor in the University of Toronto's Rotman School of Management.