Jan. 19, 2010 -- MONDAY, Jan. 18 (HealthDay News) -- If you spend time with people who exhibit self-control -- resisting the death-by-chocolate cake after a restaurant meal, for instance -- you can expect your own self-control to be pretty good, too, according to new research.
But the opposite seems true, too: Spending time with people with less-than-ideal self-control will influence you negatively, the researchers found.
"Before, we knew people tended to hang out with other people who were like themselves," said Michelle vanDellen, a visiting assistant professor of psychology at the University of Georgia, who led the research, which was published online in the Personality and Social Psychology Bulletin.
"But in these studies, we actually show there is a direct effect of our friends' behavior on our own behavior," vanDellen said. The findings apply, she said, "not only to the people we [choose to] hang out with, but those we are forced to hang out with," such as co-workers on the job.
The conclusions came from five studies conducted by vanDellen and her co-author, Rick Hoyle of Duke University.
The best study, she said, and the most fun, involved 71 participants and two plates of food -- one stacked with carrot sticks, the other with freshly baked chocolate chip cookies. The participants either watched someone exhibit self-control by eating the carrots and leaving the cookies, or vice versa. Later, the participants took self-control tests (not involving cookies and carrots). Those who had watched a person eat cookies did less well than those who had watched someone eat carrots.
In another study, the researchers found that 36 participants randomly assigned to think of a friend with good self-control persisted longer on a handgrip test used to measure self-control than did the participants assigned to think about a friend with bad self-control.
Another study involved assigning 42 people to list the names of friends with good and bad self-control. As the participants took a test designed to measure self-control, a name was flashed very briefly on a computer screen. Those who saw the name of a friend with good self-control did better on the test than those who saw the name of a friend with poor self-control.
The researchers also assigned 112 people to write about a friend with good self-control, a friend with bad self-control or an outgoing friend. Those who wrote about a friend with good self-control did best on a test of self-control, those who wrote about a friend with bad self-control did worst and those who wrote about an outgoing friend scored in between the others.
In the fifth study, 117 people were randomly assigned to write about friends with good or bad self-control. Those who wrote about a friend with good self-control did better on word identification tests related to self-control, the researchers found.
"I think the message is really two-fold," vanDellen said of the research. "The first is, one way you can improve your behavior is by finding social networkers that support you." It makes sense, she said, to seek out people you know have self-control if you want to boost your own.
The other message, she said, is accountability. The research suggests that others aren't just watching your behavior when you show a lack of self-control but might actually be influenced by it. If a woman's husband is trying to lose weight, for instance, the last thing she should do is act like a lazy person who doesn't exercise in front of him, she said.
The research findings make sense, said Connie Diekman, director of university nutrition at Washington University in St. Louis. "Surrounding yourself with motivated, healthy people improves your odds of staying in control," she said.
Diekman said that's certainly the case with healthy eating. "When it comes to making healthy choices, we know that it is easier to skip dessert, limit portions or purchase the right foods if others we are with support these behaviors," she said.
The American Psychological Association has information on healthy habits for families.
SOURCES: Michelle R. vanDellen, Ph.D., visiting assistant professor of psychology, University of Georgia, Athens; Connie Diekman, R.D., director, university nutrition, Washington University, St. Louis; Dec. 15, 2009, Personality and Social Psychology Bulletin, online