"Eventually, you are playing not for the money, but to stay in the zone because it feels peaceful and a little jazzy," she says.
The machines were even designed to capitalize on that "just keep trying" feeling, she says, with little messages on the video game versions popping up after a near-miss to say, "Not quite! Almost!"
While problem gamblers often will compare the betting buzz to highs gained from cocaine or other substances, calling gambling an addiction -- and thus putting it on par with substance addictions like alcoholism -- is still a contentious claim among some in the field.
"Classifying gambling as a behavioral issue has brought up some problems because it doesn't quite fit," says Dr. Timothy Fong, director of the UCLA Gambling Studies Program.
"Some people said it is like obsessive compulsive disorder," he says. "Some people said it was just people being depressed and acting out through gambling. Other people said this is a byproduct of people being antisocial."
As such, gambling problems have "much greater stigma in society and in the medical community," he adds, because they're not always seen as a legitimate medical issue.
"It is an addiction that a lot of people don't understand," Zaharevitz says, "because nothing is ingested, there's nothing to smell on our breaths, there are no track marks on our arms ... but it is a true addiction."
It is one that, in her case, led her to commit a felony to get a fix -- stealing a neighbor's checks in order to continue gambling when the money ran out.
Fong and Franklin agree with the drug abuse comparisons, saying that gambling problems are "absolutely" an addiction, as evidenced by the changes in the brain.
"Society tends to judge this behavior, saying, 'Oh, they're immature, they're lazy,'" Franklin says. "But now, when you look inside the brain, it helps us see the 'keep playing' message as more of a hard wiring difference. This study goes a long way towards understanding what makes the person with a gambling problem behave this way."
With the help of research like Clark's, public perception of gambling issues is now shifting, experts say, and with it the stigma attached to this problem.
Research like this "makes it much easier to stop judging problem gamblers and start helping," Franklin says.