Seeing teens standing together, but totally ignoring each other is a common sight these days. According to a survey conducted by the Pew Research Center, 78% teens aged between 12 and 17 have mobile phones. And they are not just using it to call their parents. One in four teens have access to the internet, far more than adults. So is cell phone really a good thing for teens? What are the negative effects of cell phones on teenagers? Read on to find the answer.