The computer gaming industry uses a powerful psychological device that could make some fans play compulsively, an investigation has found.
Games designer Adrian Hon, chief creative officer of gaming giant, SixToStart, said producers use a simple technique based on a 1950s study of rats feeding themselves by pressing a lever.
The "variable ratio of reinforcement" (or operant conditioning) basically sees people acting a certain way because they are rewarded for that behaviour.
Mr Hon said: "I think people don't necessarily understand how powerful some game mechanics can be. It's one thing to think: 'OK, I'm playing too much', but it's another to just stop playing, because some games are designed in a manner that you just don't want to leave."
He added: "I think the industry needs to be thinking about this a lot more. Because games are becoming so much more widespread and because they're becoming so much more powerful."
Scotland has a strong international reputation in the gaming industry, with best-selling game Grand Theft Auto created by Edinburgh-based firm Rockstar North.
Edinburgh-based author Sue Palmer, who wrote Toxic Childhood and 21st Century Boys, said: "Research has shown that if you reward someone for an action all the time they get bored or if you don't reward them enough they become despondent. The trick gaming companies use is rewarding players intermittently - and it is this that becomes addictive. So you have people hooked on a game that gives them a chance to collect life-enhancing tokens, or virtual money to buy weapons."
Ms Palmer added: "My advice to parents is to limit their child's time spent playing computer games and explain why they are not good for them."
Professor Mark Griffiths, from Nottingham Trent University's International Gaming Research Unit, said: "It's a neat little psychological trick, and for most people this will not be something that's bad, but if you've got… that vulnerability or susceptibility to addiction that will keep you in the game probably far in excess of what the normal person would do."
Prof Griffiths said insufficient research has been done: "The good news is that for the vast majority of people video gaming is something that is very positive in their lives.But we have to take on board that there is a growing literature that suggests that for a small but significant minority things like gaming can be potentially problematic."
The United Kingdom Interactive Entertainment Association (UKIE) is also calling for more research into the issue and urging parents to keep tabs on their children's console use.
Its spokesman, Ian Rawlinson, said: "Looking at the evidence, there's a very mixed picture and there's not a clear view on whether the actual game itself is causing addiction or whether it is a problem around certain aggressive compulsive behaviours of individuals."
The investigation will feature in tonight's edition of Panorama on BBC1.