TUESDAY, Nov. 13 (HealthDay News) -- Cigarette packs featuring images of cadavers, a field of weathered tombstones or yellow-toothed, cancer-riddled mouths may indeed convince smokers to quit, a new study suggests, and those kinds of pictures may have a particularly strong impact on less-educated smokers who are less informed about health.

Researchers from the University of South Carolina wanted to examine how cigarette packages featuring pictures related to the health fallout of smoking influenced adult smokers compared to words-only warnings. They recruited a less-educated smoking population because other studies show people in lower socioeconomic groups with lower levels of education are among the heaviest smokers with the highest tobacco-related disease rates.

Since the mid-1980s, tobacco products in the United States have carried the same text-only warnings about the dangers of tobacco use. The 2009 Family Smoking Prevention and Tobacco Control Act, however, gave the U.S. Food and Drug Administration more control over tobacco product labeling, and prominent visual images were going to be required on cigarette packages this year.

Before the new labeling rolled out, however, tobacco companies stalled the action in court, arguing such labels violated the right to free speech.

While the issue is being wrangled over legally, the researchers said they wanted to explore visual-warning use further, "to inform future warning-label policy development and implementation," they wrote in their study, which is scheduled for publication in the December issue of the American Journal of Preventive Medicine.

"Research on cigarette warnings in the United States and other countries has repeatedly shown that pictures work better than text," said lead investigator Dr. James Thrasher, an associate professor in the department of health promotion, education and behavior at the University of South Carolina in Columbia. "Our research supports this finding while also showing what tobacco researchers have assumed for a while -- that warnings with pictures work particularly well among smokers with low levels of literacy."

The scientists recruited nearly 1,000 adult smokers for the study from public places such as grocery stores, sporting events and flea markets across South Carolina. They asked them questions about their education, salary levels, race and smoking habits. All of the participants had to have smoked at least 100 cigarettes during their lifetime and had to currently be daily smokers.

To assess their health literacy, the researchers asked each smoker to interpret a nutrition label. The participants were randomly assigned to one of two groups.

The control group of 207 male and female smokers, aged 18 and up, were shown four text-only warnings currently used on cigarette packs, which warn of lung cancer, pregnancy complications and other medical problems.

The other 774 individuals, also a mix of men and women over 18 who smoked regularly, were shown nine different cigarette packs that carried warning text and pictures showing the consequences of smoking. While some visuals were very graphic -- including a close-up of a gray and scarred cadaver chest -- other pictures featured a distraught person or included more abstract visual images warning of cancer, heart disease and stroke.

Both groups rated the messages according to credibility, personal relevance and effectiveness. Smokers' ratings of personal relevance and effectiveness were higher for the warnings with pictures compared to the warnings with just words. Smokers with low health literacy rated the warning labels with pictures as more credible than text-only messages, the authors reported.

The warnings with very graphic imagery were rated as the most effective by smokers with both high and low health literacy, and by those from both white and black ethnic groups.

"I'm not that surprised with what it finally showed," said Dr. Aditi Satti, director of the Smoking Cessation Program and an assistant professor of medicine at Temple University Health System, in Philadelphia. Satti was not involved in the research.

"The study did target patients who might not listen to other types of messages -- a lower-income, less educated population," she said. "A picture is probably worth a thousand words in this type of patient."

Whether an image on a cigarette package is going to correlate to increasing quit rates is unclear yet, added Satti, but she said including pictures on warning labels is a good first step.

"It gets people at least thinking about what the consequences of smoking cigarettes are. It gets them in the contemplation state," Satti said. She also pointed out that people live in a more visual world now, with quick images on television, in games and in movies, so this type of study in younger adolescent smokers is also worth exploring.

According to the U.S. Centers for Disease Control and Prevention, 21 percent of the adult population smokes. It's the leading cause of early, preventable death in the United States, and linked to 443,000 deaths a year and close to $200 billion in medical expenses and lost productivity.

"The U.S. should put prominent, graphic warnings on cigarette packages," Thrasher said. "Smoking is highest among people with the least education in the U.S., and the government needs to do something about it."

More information

For more on quitting smoking, go to the U.S. Centers for Disease Control and Prevention.