A new study has been published that suggests children who play violent video games are likely to show increased aggression for some months afterwards.

The study, carried out by Iowa State University and published in the journal Pediatrics, was undertaken in an attempt to answer the popular question of whether violent video games cause aggressive behaviour, or if aggressive people are drawn to violent games.

ISU psychology professor Craig Anderson led the study, and decided to attempt to address this question by comparing young gamers in America and Japan.

An argument against video games causing violence if often that Japan has such a high number of gamers yet such a low rate of reported violence, and therefore that games cannot be a sole contributing factor in aggressive behaviour.

In an attempt to address this, Anderson took results from a previous study he carried out for his 2007-published book, Violent Video Game Effects on Children and Adolescents, with research from an associate professor of psychology at Ochanomizu University in Japan.

There were 364 children from Minnesota, aged 9-12, involved in the study, each of which was asked to list their three favourite games. They were then asked to rate themselves on how violent they believed themselves to be, and account reports from peers and teachers were taken in to account as well.

Those children subjected to violent games were reported to be more likely to get into a fight or show signs of physical aggression around 5 months after playing a violent game.

These results were then compared to the research from Japan, where a total of 1231 Japanese students between the ages of 12-18 were observed. The number of hours, as well as the violence in their favourite game genres was noted, and then the students were also asked to rate themselves on physical aggression - this time with no external reports being taken at all.

All in all, it doesn't sound like the most reliable forms of data collection but who are we to judge?

Anderson claims to have found similar findings from both studies, and was confident enough to state: "We now have conclusive evidence that playing violent video games has harmful effects on children and adolescents".

"When you find consistent effects across two very different cultures, you're looking at a pretty powerful phenomenon. One can no longer claim this is somehow a uniquely-American phenomenon. This is a general phenomenon that occurs across cultures."

He continued: "The argument has been made - it's not a very good argument, but it's been made by the video game industry - that all our research on violent video game effects must be wrong because Japanese kids play a lot of violent video games and Japan has a low violence rate".

"By gathering data from Japan, we can test that hypothesis directly and ask, 'Is it the case that Japanese kids are totally unaffected by playing violent video games?' And of course, they aren't. They're affected pretty much the same way American kids are."

The report has already received a backlash from both the industry and academics.

Texas A&M International University assistant professor of psychology Christopher Ferguson said in an open letter to the journal Pediatrics: "There are numerous flaws in the literature review, methodology and conclusions that greatly reduce my enthusiasm for [the study], and call into question the meaningfulness of it".

And while academics fight over what has been omitted from the study, the Entertainment Consumers Association has released a well-worded statement that slams the study point blank.

"For the better part of the past decade we - game consumers, makers, sellers and creators - have been waiting for the results of an unbiased, longitudinal and comprehensive study to be done which will inform us about the potential harmful effects of entertainment products on our children", it said.

"Unfortunately, with the report published in the latest issue of Pediatrics, we remain wanting."