Teenagers who play lots of violent video games may have poorer moral judgement, a new study suggests.

A Canadian researcher set out to investigate whether playing video games affected teenagers' moral reasoning - in other words, their ability to clearly see between right and wrong and take other people's perspectives into account.

Mirjana Bajovic looked at teenagers aged 13 and 14, asking them about their game playing habits. She also used an established scale of one to four to determine their level of moral reasoning.

She found a big difference between those who played violent video games for one hour a day, and those who played for at least three hours per day. Those who played more displayed lower levels of moral maturity.

Previous research has shown that teenagers who do not advance beyond this point ‘usually have not had enough opportunities to take different roles or consider the perspective of others in real life'.

"The present results indicate that some adolescents in the violent video game playing group, who spent three or more hours a day playing violent video games, while assumingly detached from the outside world, are deprived of such opportunities," she said.

Ms Bajovic believes that these findings are due to both the length of time playing the games and their content.

"Spending too much time within the virtual world of violence may prevent gamers from getting involved in different positive social experiences in real life, and in developing a positive sense of what is right and wrong," she noted.

Her study also found that moral judgement did not appear to be affected if the teenagers played non-violent video games.

She acknowledged that prohibiting teenagers from playing these games ‘is not realistic'. However, she urged parents to make themselves aware of what games their children are playing, and for how long, as they may influence their teens' ‘attitudes, behaviour and moral development'.

She also urged parents and teachers to discuss ‘what's right and wrong within the stories depicted in video games'. While teenagers may not enjoy this discussion, they would probably prefer that option to an outright gaming ban, she added.

Details of these findings are published in the journal, Educational Media International.