Associated Press - August 10, 2007

Many of the numbers that make news about how we feel, think and behave are derived from studying a narrow population: college students. It’s cheap for social scientists to tap into the on-campus research pool - everyone from psychology majors who must participate in studies for course credit to students who respond to posters promising a few bucks if they sign up.

Consider just three studies that have received press in the past month. In one, muscular men were twice as likely as their less well-built brethren to have had more than three sex partners - at least according to 99 UCLA undergraduates. Another, an examination of six separate studies that tape-recorded college students’ conversations, found that women, despite being stereotyped as relatively chatty, spoke just 3 percent more words each day than men. And in the third, 40 undergraduates at Washington University in St. Louis were 6 percent more likely to complete verbal jokes and 14 percent more likely to complete visual jests than 41 older study participants.

College students are “essentially free,” says Brian Nosek, a psychology professor at the University of Virginia. “We walk out of our office, and there they are.” The epitome of a convenience sample, they have become the basis for what some critics call the “science of the sophomore.”

But psychologists may be getting what they pay for. College students aren’t representative by age, wealth, income, educational level or geographic location. “What if you studied 7-year-old kids and made inferences about geriatrics?” asks Robert Peterson, a marketing professor at the University of Texas, Austin. “Everyone would say you can’t do that. But you can use these college students.”

Prof. Peterson scoured the literature for examples of studies that examined the same psychological relationships in students and nonstudents. In almost half of the 63 relationships he examined, there were major discrepancies between students and nonstudents: The two groups either produced contradictory results, or one showed an effect at least twice as great as the other.

In a follow-up study, not yet published, Prof. Peterson demonstrated that even college students are far from homogeneous. With help from faculty at 58 schools in 31 states, he surveyed undergraduate business students across the country and found that they vary widely from school to school. That means a professor studying the relationship between students’ attitudes toward capitalism and business ethics at one school could reach a sharply different conclusion than a professor at another school.

“People have always been aware of this issue,” Prof. Peterson says, but many have chosen to ignore it. A 1986 paper by David Sears, a UCLA psychology professor, documented the increased use of college students for research in the prior quarter century and explored the potential biases that might introduce. In the meantime, the use of college students has, if anything, risen, researchers say.

Authors of the recent studies on sex, chattiness and humor acknowledge the limitations of their research pool. But they argue that college students do just fine for purposes of studying basic cognitive processes. Others agree. “If you think all people have the same attitudes as introductory psychology students, that’s really problematic,” says Tony Bogaert, a psychology professor at Brock University in St. Catharine’s, Ontario. “But if you’re looking at cognitive processes, intro psych students probably work OK.”

After all, every study is hampered by possible differences between those who volunteer to participate and those who don’t, whether they’re college students or a broader group.

In any case, the fault often lies not with the researchers, who are careful not to overstate the impact of their findings, but with the news articles suggesting the numbers apply to all humanity. “Even if you only focus on college students, the results are still generalizable to millions of Americans,” says David Frederick, a UCLA psychology graduate student and lead author of the study on muscularity and sex partners.

Prof. Nosek, a critic of the science of the sophomore, responds that college students are still developing their personalities and behavior. “There is no other time outside my life as an undergraduate where I thought it would be a good idea to wear all my clothes inside out,” he says, or to “stay up for as many hours in a row as I could just to see what happens.”

To widen the pool of people answering questions about, say, all-nighters, Prof. Nosek has submitted a proposal to the National Institutes of Health to fund the creation of an international, online research panel. That would build on studies his laboratory has already administered online at ProjectImplicit.net.

Online research has its own problems, but at least it taps into the hundreds of millions of people who are online globally, rather than just the hundreds of people enrolled in Psych 101.

“The scientific reward structure does not benefit someone who puts in the enormous effort” to create a representative research sample, Prof. Nosek says. “The way to change researchers’ data habits is to make it easier to collect data in a more generalizable way.”

Copyright 2007 The Associated Press.