The makers of slot machines may rely on the lure of life-changing jackpots to attract customers, but the machines' ability to hook so deeply into a player's cerebral cortex derives from one of the more powerful human feedback mechanisms, a phenomenon behavioral scientists call infrequent random reinforcement, or "intermittent reward." Children whose parents consistently shower them with love and attention tend to take that devotion for granted. Those who know they'll never be rewarded by their parents stop trying after a while. But those who are rewarded only intermittently -- in the fashion of a slot machine -- will often pursue positive outcomes with a persistent tenacity. "That hard-wiring that nature gave us didn't anticipate electronic gaming devices," says Howard Shaffer, director of the division on addictions at Harvard Medical School and perhaps the country's foremost authority on gambling disorders.

"The slot machine is brilliantly designed from a behavioral psychology perspective," says Nancy Petry, a professor of psychiatry at the University of Connecticut School of Medicine. "The people who are making these machines are using all the behavioral techniques to increase the probability that the behavior of gambling will reoccur." She refers to intermittent reward and "second-order conditioning" -- the lights and sounds that go off when a player wins, for example, or the two cherries in a row that convinces people they're getting closer.

"No other form of gambling manipulates the human mind as beautifully as these machines," concludes Petry, who has studied gambling treatments since 1998. "I think that's why that's the most popular form of gambling with which people get into trouble."

Anti-gambling activists refer to slots as "the crack cocaine of gambling." Though gambling's loudest critics tend to be alarmists, the crack analogy may be apt. Just as crack addicts have frequently seemed to self-destruct much faster than those abusing powdered cocaine, there is abundant, albeit still largely anecdotal, evidence suggesting that the same is true of today's computer-driven slot machines -- video-based slots especially. Where social workers once found that the woes of a typical problem gambler tended to mount gradually -- with a period of 20 or more years commonly passing between a first wager and a bottoming-out event like bankruptcy, divorce or even suicide -- addiction cycles of a few years are, if not typical, commonplace among slots players.

"Treatment folks are definitely identifying people who are experiencing what we call 'telescoping' -- a shortening of the period of time that it takes for someone to get into trouble," says Rachel Volberg, president of the National Council on Problem Gambling and the author of "When the Chips Are Down: Problem Gambling in America." Volberg, who runs Gemini Research, an organization that specializes in gambling-related investigations, says it remains to be seen whether the problem lies in "something special about these machines or in the people who prefer playing them." Female slots players in particular, Petry says, "tend to experience this telescoping phenomenon -- and we know from research that women are quicker to seek treatment."

Gambling counselors regularly encounter people like Ricky Brumfield, a working-class Phoenix woman who won $3,700 the first time she ever touched a slot machine -- a day that turned out to be the unluckiest of her life. That was in 1997, when Brumfield, then 43, traveled to Las Vegas to help a friend celebrate the Fourth of July. Within nine months, she had hocked her jewelry and gone through $100,000 in cash and credit-card debt. She only stopped, she confesses, because the Sheriff's Department arrested her on child-abuse charges for leaving her two young kids locked in a car in a casino parking lot while she played the slots inside. "I knew it was really wrong to do that, but the urge to go into the casino was stronger than my instincts as a mother," Brumfield says. She had only recently had back surgery, but she found that when she played, she never felt pain. "I think the dopamine and serotonin levels, when they kicked in -- that blocked off the pain," says Brumfield, who now works for the Arizona Council on Compulsive Gambling. "You feel hypnotized by the machine. You don't think of anything else." Near the end, the hold the machines had over her, she says, was akin to that of an unfaithful lover. She would fall into a jealous rage when a favorite machine paid a jackpot to another, less devoted player.

"Slot machines have a different impact on the brain than other forms of gambling," Howard Shaffer says. Unlike table games, which are played in groups, slots are played in isolation, and therefore they lack the same safeguards social situations provide. "And because the video form is faster than the mechanical form, they hold the potential to behave in the fashion of psychostimulants, like cocaine or amphetamines. They energize and de-energize the brain in more rapid cycles. The faster on, faster off, the greater the risk." Colleagues of Shaffer have compared the brain scans of people high on cocaine with those of people while gambling: similar neurocircuitry is lighted up in both sets of images.

Shaffer predicts that in time electronic games will "protect players." Just as the car industry implemented basic technologies like seat belts to save lives, he expects the gambling industry (which finances many of his studies) to eventually employ strategies to interrupt people when they play too fast. As Bill Eadington, the University of Nevada, Reno, professor and a consultant to Indian tribes, governments and casinos around the world, puts it, "I worry that we're burning out players too fast."

The typical slots player initiates a new game every six seconds. That works out to 10 games per minute, 600 per hour. If the average player bets $2 a spin, that player is wagering roughly $1,200 every hour. Slot designers have experimented with machines that play even faster, but the industry standard remains a six-second cycle. "It wouldn't be much fun if we took your money any faster than that," [Joe] Kaminkow [slot machine design hotshot] told me with a slight shrug of his shoulder, suggesting that just how fast people play is entirely up to him.

I asked Kaminkow if he ever worried that the potent mix of TV, technology and the prodigious talents of his creative people will produce machines that are too powerful. "What kind of question is that?" he replied. In his natural state, Kaminkow is a breezy and sarcastic jokester who revels in politically incorrect jokes. But he suddenly sounded as if he were addressing a Rotary Club. "I take responsible gaming very seriously," he said. "We're not an alcohol, we're not a drug." He is in the entertainment business, he added, a "maker of small little movies" that bring a touch of joy and laughter to the lives of the elderly and others.

"I'm not looking for people who say, 'I spent my milk money,"' he said. "I think people need to be very responsible in their gaming habits. I know I am."

It's interesting to compare the attitude and behavior of the slot machine industry to the strategies for success of viruses. A virus which quickly kills its host is a complete failure, because the purpose of the virus is not to do bad things to the host (that's just what it feels like from the hosts's viewpoint), but to use the host to make many, many copies of itself to send out and infect other hosts. The goal is reproduction, and the most successful virus is one which keeps the hosts sick enough that the host's immune system can't fight off the virus, but not so sick that the host dies, thus cutting off the possibility of more viral reproduction. The same is true of other parasites, which aim to keep the host alive and available for exploitation without making it so feeble that the parasite loses its source of food and energy.

Compare this to the statement above: ""I worry that we're burning out players too fast." They're not worried that players are burning out, that they're becoming addicted and squandering money in the slots (why would they worry about that, since it's the very purpose of the machine in the first place), they're worried that their burning out "too fast" -- that is, so fast that they cannot be good long-term hosts for the gambling parasite.