Australian National University PhD student Olivia Metcalf has produced some of the first scientific evidence that video gaming is indeed addictive.

Ms Metcalf recruited 38 gamers from video game stores, internet cafes and on campus at the university, all of whom played games for more than five hours a week, averaging between 10 and 15 hours. Her research found some people who spent a lot of time playing video games could not stop themselves thinking about gaming, a pattern typical of addiction.

They completed a questionnaire on whether they had withdrawals, cravings and negative consequences from their gaming. The questions found 20 participants were addicts.

Ms Metcalf then presented the participants with a series of different coloured words, and asked them to respond to the colours of the words, not their meaning.

She found gaming addicts took significantly longer to name the colour of gaming-related words compared with non-gaming words, while gamers who were not addicted did not show any difference in response times.

''We found that the attention system of an excessive gamer gives top priority to gaming information,'' she said.

''Even if they don't want to think about gaming, they are unable to stop themselves.''

Ms Metcalf said these thought patterns were likely to make it difficult for an addict to stop gaming, or cut back the hours they spent playing.

The participants played role playing games, including the hugely popular World of Warcraft, and were split 60 per cent men, 40 per cent women.

There was no difference in the hours spent playing video games by addicts and non-addicts.

''It's not the hours they played, it's their relationship with the game,'' Ms Metcalf said.