"You can lose a lot — it's so quick, the next roll, the next roll, next roll… and so continuous."

Melissa Stewart, another researcher in the lab, said gambling problems arise up to four times more quickly among people who play slots than among those who play other casino games.

Young, Stewart and their colleagues are trying to unravel the factors that play a role in slot-machine addiction.

In the Carleton gambling lab, volunteers don a virtual-reality visor and enter a virtual casino. They can walk past banks of slot machines and hear the clunk and chime of other people playing. And they can sit down and play themselves, spinning three reels of lemons, cherries and lucky sevens at the push of a button.

The spinning symbols are just for show — the machine knows whether you've won or lost the instant you pull the lever, say the researchers. Using the virtual machines, they can see how players react to outcomes such as a near miss, where the symbols almost line up, but not quite.

"The symbols on the reel are arranged such that near misses occur frequently," said Stewart. "You don't actually win but you feel like you are almost winning, so you keep playing."

The researchers are trying to find out why people start gambling and why many continue, even when they face negative consequences.

Addicts seek escape Young said almost all gamblers are motivated by the thrill of winning, but those with gambling problems are more likely to use gambling as an escape.

"They crave the buzz or the excitement that comes from gambling, but they'll also crave the relief from depression."

Carleton University professor Matthew Young says slot machines allow people to lose a lot of money in a short amount of time. (CBC) "Mary," an Ottawa woman who is recovering from a gambling addiction and didn't want her real name used, said she started playing slots after retiring and getting divorced.

"It got so bad at the end that even if I did win, I'd just stay 'til I lost it all," she told CBC News. "I mean, I've stayed till I lost it all, won it all back and lost it all again — just crazy."

Young said slots allow people to lose a lot of money in a short amount of time because the games are so brief. Also, they don't need to take a break between spins as they do with card games.

The use of casino cards, which allow electronic payment in lieu of cash, has boosted the rate at which people can lose money, Young said, because players can use the cards to make larger bets. If they win, they no longer have to wait for their coins to pour into a bucket before playing again as they once did, Young added.

Using their results, the researchers plan to develop strategies for making slot machines less addictive.