In the past several years, governments and jurisdictions around the world have decided that one way to address problem gambling is to require gambling hot spots—like casinos and lottery ticket sales offices—to post signs warning about the dangers of gambling. In 1999, for example, the congressionally mandated National Gambling Impact Study included warning signs as one of its many recommendations to reduce the toll of problem gambling.

For psychologist James Whelan, PhD, the 1999 study and others like it raised an interesting question: Could warning signs actually stop people from gambling irresponsibly?

"It follows from what's been done with tobacco and alcohol products," says Whelan, who heads the Institute for Gambling Education and Research at the University of Memphis. "But the evidence regarding warning labels is pretty mixed. These messages seem to make people more cognizant of risks, but there's little data about whether they change behavior."

Now, two studies in the March issue of Psychology of Addictive Behaviors (Vol. 20, No. 1) explore this issue further, together suggesting that some warning messages may be able to influence behavior—but not through providing information alone. One, by psychologist and gambling researcher Robert Williams, PhD, of the University of Lethbridge in Alberta, Canada, confirms what many addiction researchers suspected: Knowledge of gambling risks by itself—even extremely thorough knowledge—is unlikely to change anyone's gambling behavior.

However, the second study, by Whelan and his colleagues, suggests that carefully designed and deployed warning messages may, at least in the short term, be able to convince people to gamble more responsibly.

The limits of knowledge

In the first study, Williams and his colleague, University of Lethbridge math professor Dennis Connolly, PhD, wanted to see whether people would gamble less frequently if they gained an in-depth understanding of the statistics of gambling, particularly the statistical reasons why the odds are always stacked in the house's favor.

Williams and Connolly realized that they had a captive audience in Connolly's undergraduate statistics classes. Connolly advertised that one of his semester-long introductory statistics classes would focus on gambling statistics. The 198 students who signed up for that section became the experimental group, while two other groups of students—a 138-person introductory history class and a 134-person introductory statistics class that didn't focus on gambling—served as controls.

In his gambling statistics class, Connolly devoted five out of 10 lectures on probability to gambling probabilities. He also included a special lecture on "gambling fallacies," such as people's irrational belief that they can control the outcome of clearly random events like tossing dice. Finally, he included four lab sessions in which students tried out games of chance such as blackjack, roulette and craps.

"My graduate student at the time was a blackjack dealer at the local casino for her part-time job," Williams says, "so we sent her into these labs to clean the students out—which she did reliably."

A follow-up questionnaire completed six months after the semester ended revealed that the students who completed the gambling statistics class were, as expected, much better than the control-group students at calculating basic gambling odds and were more aware of common gambling fallacies.

However, much to the researchers' initial surprise, the students' gambling behavior hadn't changed. The amount of time and money these knowledgeable students spent gambling—in casinos, on sports and among friends—remained the same as it was before they took the class, and not significantly different than the students in the control groups.

"I have to reiterate how substantial this intervention was," Williams says. "The students received hours of instruction, and they couldn't afford to ignore it because it was part of a class and they were getting tested on it."

To psychologist Robert Ladouceur, PhD, who studies the psychology of gambling at Laval University in Quebec City, the results make sense. In a study published in Gambling Research in 2004 (Vol. 16, No. 1, pages 25–31), Ladouceur found that while gambling, a group of mathematics and statistics graduate students made just as many error-laden statements about the statistics of gambling as a group of history and literature students.

"It makes sense to think that people gamble because they lack knowledge, and that if you teach them basic statistics that will help them keep a logical perspective on the game," Ladouceur says. "But what we've found is that it's not knowledge that's important—it's a question of being aware of what drives you when you are in a gambling situation."

Williams agrees that upon reflection the results make sense. "There's been a lot of relevant research on substance abuse, which has shown that information is a precursor to behavioral change but not sufficient on its own to change behavior," he explains. "Gambling research is still a fairly new field, and to me this was simply a wake-up call and a reminder not to reinvent the wheel."

What makes warnings work?

If knowledge alone is not enough to change gambling behavior, then what is? That's the question Whelan and his colleagues addressed in their study of gambling warning messages. In the study, the researchers brought undergraduate participants into a lab designed to look like a casino. The students played a computerized roulette game in which they could win "money" that they could exchange for raffle tickets for tempting prizes.

Participants in the control group first watched a short video on the history of roulette, while participants in the experimental group watched a video that explained that people hold irrational beliefs about their control over the outcome of gambling games.

Then, all of the participants played the roulette game for as long as they wished. However, participants in the experimental group also saw warning messages flash on the screen every three to six spins. Whelan and his colleagues delved into the literature on warning messages to find out what researchers had found to be most effective. What they discovered, he says, was that short, simple, to the point messages written at a fourth-grade reading level worked best.

The messages they eventually used in their study included warnings such as "If you bet more to make up your losses, you're likely to lose more money" and "If you continue to gamble, you'll eventually lose money." The warning messages were also interactive: Participants had to click on them in order to make them disappear and continue with the game.

Although the participants who received the warning messages continued to gamble for just as long as the control participants, the warning messages appeared to work. Participants who read them gambled more conservatively and, in the end, lost less than the control participants.

Of course, there were many differences between this study and the one by Williams and Connolly: It measured lab-based gambling behavior rather than real-world behavior, and it measured immediate rather than long-term change.

Still, says Whelan, the results indicate that carefully designed warning messages could possibly affect behavior.

"I don't think putting a poster with 'play responsibly' at the front door of a casino is going to be enough," he says. "But I think this might translate to the real world."