Graphic photographs on cigarette warning labels appear to be more effective than text warnings in convincing smokers to try to quit, a new study suggests.

Researchers from the University of North Carolina at Chapel Hill reviewed previous research that compared graphic images to text warnings. They found the pictures received more attention, created stronger emotional reactions and negative attitudes about smoking, and increased the odds that smokers would vow to quit.

“They say a picture is worth a thousand words – that really seems to be the case here,” lead study author Seth Noar told Reuters.

According to the World Health Organization, as of December 2012, 30 countries required warning images on at least half of the front and back of cigarette packages with anti-smoking messages in the local language.

The 37 studies analyzed by Noar’s team included more than 33,000 people in total. Graphic images were more likely than words to convince smokers to think more about the effects of smoking. They also lowered cravings and increased aversion to cigarettes.

“Smokers know that cigarettes are bad for them, but they likely tune out vague warnings that they have seen for years, such as `smoking causes cancer,’” Noar said. “Seeing images of diseased lungs and people suffering from the negative health impacts of smoking appear to affect smokers in ways that simple text-only messages cannot achieve.”

The findings appear in the journal Tobacco Control.