One of his discoveries: "Teens who use Facebook more often show more narcissistic tendencies," he says.
It makes them antisocial and aggressive
"Young adults who have a strong Facebook presence show more signs of other psychological disorders, including antisocial behaviors, mania and aggressive tendencies," Rosen explains.
It gives them anxiety
"Daily overuse of media and technology has a negative effect on the health of all children, preteens and teenagers by making them more prone to anxiety," Rosen adds.
It makes them depressed (as well as give them other psychological disorders)
Facebook use in teens can also lead to "depression, and other psychological disorders, as well as by making them more susceptible to future health problems."
It distracts them
"Facebook can be distracting and can negatively impact learning," says Rosen. "Studies found that middle school, high school and college students who checked Facebook at least once during a 15-minute study period achieved lower grades."
It makes them nicer (in the virtual sense)
"Young adults who spend more time on Facebook are better at showing 'virtual empathy' to their online friends," Rosen points out.
It make them more social
"Online social networking can help introverted adolescents learn how to socialize behind the safety of various screens, ranging from a two-inch smartphone to a 17-inch laptop," says Rosen.
It engages them to learn
"Social networking can provide tools for teaching in compelling ways that engage young students," Rosen explains.