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FAU Psychology Professor Studies How Friendship Influences Youth Behavior

FORT LAUDERDALE, FL (August 30, 2011) – Brett Laursen, Ph.D., a psychology professor and director of graduate studies in the Charles E. Schmidt College of Science at Florida Atlantic University recently published results from a study on how friends influence over problem behaviors in a sample of middle and high school students. The findings were published in August in the Journal of Abnormal Psychology, a journal of the American Psychological Association. Part of a larger research collaboration with colleagues Hakan Stattin, Ph.D., and Margaret Kerr, Ph.D., from Orebro University in Sweden, Laursen’s report examined three-years-worth of data on alcohol intoxication and delinquency, the latter defined by such nonviolent offenses as property damage, truancy and shoplifting.

“Parents often worry about the influence friends have over problem behavior. In this study, we answer the question, ‘Who is influencing whom to behave badly?’” said Laursen. “The answer is that the better liked member of the friend dyad is the more influential member of the dyad, for better or for worse.”

The findings indicate that if the better liked member of the dyad displayed more problem behavior than the lesser liked member of the dyad, then the lesser liked member of the dyad increased his or her subsequent alcohol consumption and delinquency. But if the better liked member of the dyad displayed less problem behavior than the less liked member of the dyad, then then less liked member of the dyad decreased his or her delinquency, and slowed the rate of increase in alcohol consumption.

The study is unique in that it included all students enrolled in middle school and high school from a small city in central Sweden. Students indicated how much they liked each other by nominating their most important peers. Acceptance or liking was measured by tallying the number of important peer nominations that each student received. Within each friendship, partners were divided according to which friend was better liked. Because everyone in town participated, it was possible to capture changes in problem behaviors for both friends and to do so for partners who were friends in school and out of school.

Social skills also might explain some of the findings. Better liked children may be more persuasive and more skilled at getting their way. But Laursen said he believes that this is unlikely to explain these results, because many friendships involve partners with similarly high or similarly low levels of social skills. Instead, Laursen explains the results in terms of interpersonal options.

“If you have more options for making new friends, you are more likely to get your current friend to do what you want,” he said. “This is certainly the case for deviant behavior, but I suspect it is also true for pro-social behavior.”

Results from the same project to be published in the journal, Personality and Individual Differences, underscore the important role that influence plays in friendship. The success of a friendship could be predicted by the degree to which two friends were similar on alcohol intoxication and delinquency. Friends that were less similar at the outset of the friendship tended not to be friends one year later. Friends that were more similar at the outset of the friendship tended to remain friends one year later and their similarity increased over time, primarily because the less well liked friend changed his or her behavior to resemble that of the better liked friend. Chris Hafen, Ph.D., of the University of Virginia, was the lead investigator on this report.

This project was funded, in part, by the Swedish Research Council and by the U.S. National Science Foundation.

For more information, contact Brett Laursen at 954-567-3683 or


Florida Atlantic University, established in 1961, officially opened its doors in 1964 as the fifth public university in Florida. In commemoration of its origin, FAU is celebrating its 50th anniversary throughout 2011. Today, the University serves more than 28,000 undergraduate and graduate students on seven campuses and sites. FAU’s world-class teaching and research faculty serves students through 10 colleges: the Dorothy F. Schmidt College of Arts & Letters, the College of Business, the College for Design and Social Inquiry, the College of Education, the College of Engineering & Computer Science, the Graduate College, the Harriet L. Wilkes Honors College, the Charles E. Schmidt College of Medicine, the Christine E. Lynn College of Nursing and the Charles E. Schmidt College of Science. FAU is ranked as a High Research Activity institution by the Carnegie Foundation for the Advancement of Teaching. For more information, visit

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