The United States is one of the few developed countries that has a decades-old, text-only warning label on cigarette packages.
The U.S. Food and Drug Administration has tried for years to add warnings with graphic images, but lawsuits from tobacco companies have halted the process.
Click here to see some of the graphic warning labels the FDA proposed.
Professor Seth Noar of UNC's Lineberger Cancer Center has analyzed 37 studies comparing people's reactions to text-only warnings versus pictorial ones.
"What is needed, both in the US and worldwide, is evidence. So, if we have evidence that shows, well, these are better—smokers pay more attention to them, it gets them thinking more about the risks of smoking, it strengthens their resolve to try to quit smoking, and that, at a larger level, it has a positive public health impact—then that's really important."
Noar says one downside is that the graphic warning labels tend to annoy or offend people, but its unclear how that impacts smoking. He says this study did not measure the actual behavior of consumers.