Players have a need to master the game, and they experience a loss of self-esteem if they don’t play well. That can lead to aggression, Ryan says.

“The idea grew out of some earlier research, where we saw that the satisfaction players get from games comes from the feeling of competence that results from the play,” says Ryan, who carried out the research with Professor Andrew Przybylski of the Oxford Internet Institute in the UK.

“We thought that the frustration that results from not playing the game well might be a cause of aggression. The theory out there is that post-game aggression is caused by the content of the game. But our results showed that post-game frustration with competence was a lot more salient as a factor.”

Ryan, who co-developed self-determination theory, a theory of motivation that says we need to fulfil certain psychological drives, says that we play games because they offer us the chance to be good at something.

“One reason people play games is to have an experience of competence,” he says. “So they don’t like it when their competence is frustrated in the gaming environment. It’s a lot like sports. When we’re playing sports, we’re trying to do our best, and achieve what we can.

“Post-game aggression also occurs in sports, when people feel frustrated, particularly by things that they weren’t able to control – like a bad call, for instance.”

We all have a psychological need to do well, and games can fulfil that need.

“Games can give people positive experiences that they may not be getting elsewhere,” says Ryan. “We asked an older man in our book Glued to Games what he felt was so satisfying about playing games. He said, ‘I have been working in my job for 20 years, and I have never levelled up. But I go home at night and play a game, and I can level up.’ He didn’t feel competent at work, but felt competent while he was playing the game.”

When we’re playing sports, or a computer game, we’re putting our ego on the line, continues Ryan: “If we lose a game, we can feel aggressive. Our ego, our self-esteem, can suffer if we don’t do well. That leads to frustration, and frustration makes people especially prone to aggressive feelings.”

Aggressive feelings are more intense if you’re playing a game that you consider yourself good at, the professor says: “If you think you should be good at something, that can make you feel worse if you do badly.”

If competence is denied, rage quitting can occur. The rage takes many forms. Gaming forums on the internet reveal gamers punching stationary objects, and breaking their controllers.

One gamer reports destroying a game disc with his car keys, another reported finding teeth marks on his controller after he had calmed down. Although the rage often results from feelings of incompetence, frustration with bad game design, or an unresponsive controller, can also be the trigger.

Ryan points out that such rage occurs in other areas of life, too.

“This is not unique to gaming. A lot of us engage in compensatory activity when we have put our self-esteem on the line,” he says.

“I used to be a caddy, and I saw a lot of unpleasant things taking place on golf courses. Some golfers had big egos, and didn’t like these being denied. Other golfers, equally good golfers who were invested in the game, had learned not take failure as a blow to the self. There are individual differences in the way people take it, and some people can moderate these feelings.”

Some people are more vulnerable to rage than others, says Ryan.

“It combines with something else that we’ve been exploring in our research, the ‘need density hypothesis’. That means that people who are having a lot of their basic psychological needs frustrated in other areas of their life, are more prone to invest in games, where they can get those needs quickly satisfied. They are more invested in the games than others,” he says.

Emotions felt while playing games, or experiencing virtual worlds, are authentic emotions, adds Ryan – they are not imitations.

“When you have an experience in a virtual world, it is still psychologically real,” he says. “When you help someone while playing a game like World of Warcraft, you get the same positive feeling as when you give directions on the street, or help somebody out in the molecular world.

“We can’t say that one feeling is real and the other is not – all these feelings are psychologically real. It’s just that some have importance in the molecular world, and some don’t.”

The new breed of virtual reality games, like Playstation VR, could heighten these emotions, he says. “Virtual reality games are going to give us a lot more immersion, and we will feel more present in the games,” says Ryan.

“There is the potential for games to be a lot more psychologically real for us. Most gamers have a pretty clear boundary between what’s virtual and what’s not – what’s a game and what isn’t a game. But that is going to be increasingly challenged.”

Ryan says that his research should not be used to back up the opinion that violent video games do not produce violence in players. That may still be proven to be true, and there is much heated debate in the scientific community about the issue.

Ryan’s study focus was on the relationship between competence and aggression: “Our research does not disprove the content hypothesis. We are just saying that competence did turn out to be very powerful in our models, relative to frustration,” he says.

But Ryan does think that the effects of games on the player may be overstated. “People like games because they can satisfy some basic needs. They come to a game with the expectation that these needs will be met, and that’s not always the case. That’s why frustration is so salient in games,” he says. People do get very involved, and can look aggressive to observers while playing.

“But the context in which the player is operating in is different to that of the person watching. It might look worse than it actually is,” Ryan says.