"Have our brains become so desensitized by a 24/7, all-you-can-eat diet of lurid flickering images that we've lost all perspective on appropriateness and compassion?" they asked. A 2007 study of 18 to 23-year-olds found they were less able to identify expressions of emotion after playing violent video games. And, while Dr. Rosen's study found that can help people relate better, it also found that excessive social networking makes some teens more prone to aggression, mania, anxiety, and depression.