Juliana Belo Gutierrez/iStockphoto/Getty Images Preteens using increasing amounts of social media perform poorer in reading, vocabulary and memory tests in early adolescence compared with those who use no or little social media. That's according to a new study that suggests a link between social media use and poorer cognition in teens. The findings are published in JAMA. "This is a really exciting study," says psychologist Mitch Prinstein at the University of North Carolina at Chapel Hill, ...