Bolding is mine...
Over six years, psychological scientists examined whether or not seeing sex on the big screen translates into sex in the real world for adolescents. Their findings, which are to be published in Psychological Science, a journal of the Association for Psychological Science, revealed not only that it did but also explained some of the reasons why.
"Much research has shown that adolescents' sexual attitudes and behaviors are influenced by media," says Ross O'Hara, currently a post-doctoral fellow at the University of Missouri, who conducted the research with other psychological scientists while at Dartmouth College. "But the role of movies has been somewhat neglected, despite other findings that movies are more influential than TV or music."
Before recruiting participants for the study, O'Hara and his fellow researchers surveyed 684 top grossing movies from 1998 to 2004. They coded the movies for seconds of sexual content, like heavy kissing or sexual intercourse. This work built on a previous survey of movies from 1950 to 2006 that found that more than 84% of these movies contained sexual content, including 68% of the G rated films, 82% of PG movies and 85% of PG-13 movies. Most of the recent films do not portray safe sex, with little mention of using contraception.
Researchers then recruited 1,228 participants who were from 12 to 14 years of age. Each participant reported which movies they had seen from a number of different collections of fifty that were randomly selected. Six years later the participants were surveyed to find out how old they were when they became sexually active and how risky their sexual behavior might have been. Did they use condoms consistently? Were they monogamous or did they have multiple partners?
"Adolescents who are exposed to more sexual content in movies start having sex at younger ages, have more sexual partners, and are less likely to use condoms with casual sexual partners," O'Hara explained.
Why do movies have these effects on adolescents? These researchers examined the role of a personality trait known as sensation-seeking. One of the great dangers of adolescence, is the predisposition for "sensation seeking" behavior. Between the ages of ten and fifteen, the tendency to seek more novel and intense stimulation of all kinds peaks. The wild hormonal surges of adolescence makes judicious thinking a bit more difficult.
O'Hara and his colleagues found that greater exposure to sexual content in movies at a young age actually led to a higher peak in sensation seeking during adolescence. As a result, sensation seeking sexual behavior can last well into the late teens and even into the early twenties if young people are exposed to these kinds of movies. But researchers point out that sexual exposure in movies tends to activate sensation seeking both because of biology and the way that boys and girls are socialized.
"These movies appear to fundamentally influence their personality through changes in sensation-seeking, " O'Hara says, "Which has far-reaching implications for all of their risk-taking behaviors."
But sensation seeking did not entirely explain these effects; the researchers also speculate that adolescents learn specific behaviors from the sexual messages in movies. Many adolescents turn to movies to acquire "sexual scripts" that offer examples of how to behave when confronted with complicated emotional situations. For 57 percent of American adolescents between the ages of 14 and 16, the media is their greatest source of sexual information. They often don't differentiate between what they see on the screen and what they must confront in daily life .