Playing violent video games for long periods of time can hold back the "moral maturity" of teenagers, according to a study in Canada. In-depth research into the behaviour of about 100 13- and 14-year-olds found over-exposure to violent games weakened empathy for others. More than half were found to play video games every single day, with violent games the most common. Researchers warned of adolescents losing a sense of "right and wrong". Brock University academics studied the behaviour of pupils at seven schools in Ontario, trying to understand the relationship between the type of video games played, the length of time spent playing and how it might affect their attitudes. The study found that playing video games was highly prevalent among this age group, usually between one and three hours a day - and playing violent games was very common. Read the full story at BBC News.