By Chelsea Karnash

PHILADELPHIA (CBS) – College is about learning and classes for sure, but there’s a strong undercurrent of drinking, experimentation and, of course, sex.

While there has been much written about “college hook-up culture” (including a recent and controversial Times article that focused on Penn), new research from New York University might just be the most interesting — and potentially worrisome — yet.

Researcher Jonathan Marc Bearak, a doctoral student in sociology, conducted the study using information from the Online College Social Life Survey, which contains data from students at 21 universities across the country on more than 10,000 hookups that was gathered between 2005 and 2011.

Using that data, Bearak uncovered several surprising things.

First, sex during a hookup becomes nearly twice as likely between freshman year and senior year of college. For women, the probability of sex during a hookup increases from 27% freshman year to 43% senior year. Among men, that percentage jumps from 33% freshman year to 52% senior year.

Second, condom use during those hookups drops by about 40% between freshman year and sophomore year before stabilizing. The probability of unprotected casual sex increases from 7% to 16% among women between freshman and sophomore year, and from 6% to 15% among men during the same time period.

“A fairly rapid normalization of unprotected casual sex occurs between the freshman and sophomore years, and thereafter condom use in coital hookups decreases little,” Bearak says.

Finally, condom rates are lowest among first year students with the most highly educated mothers.

“Students from highly educated backgrounds use condoms at a lower rate, relative to their peers, in the first year of college. These students continue to use condoms at approximately the same comparatively low rate later on,” Bearak writes. “Students from less educated families, in contrast, use condoms more consistently during year 1, but thereafter quickly adopt the behaviors typically exhibited by their peers from more highly educated backgrounds.”

Bearak says one reason for this could be that college students from higher educational backgrounds perceive the pool of sexual partners on campus as a sort of “safe zone” or feel like worries about sexually transmitted diseases don’t apply to them. Interestingly, he says that, while there are significant differences in rates of condom use for those from different educational backgrounds during freshman year, students from lower educational backgrounds adopt the practices of their peers after their first year in school, suggesting they, too, might eventually be lulled into feeling “safe” in choosing partners who are also college students.

Bearak says his findings could have implications for health and social policy, and that his results suggest the college environment greatly affects undergraduates’ behavior when it comes to sex.

To read the full study, click here.

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