Cigarette warning labels may influence smokers to quit even when they try to void seeing the labels, according to a study.

Researchers found that small, text-only warning labels like those on cigarette packs in the United States prompt people to think about the health risks of smoking, and people who notice the warnings regularly are more likely to quite.  Larger, more graphic warning labels like those in other countries, such as Australia, were better at getting people's attention and motivating them to attempt quitting.

"Warning labels vary widely from country to country but it's clear that once people see the labels, the same psychological and emotional processes are involved in making people consider quitting smoking," Hua-Hie Yong, lead author of the study, said in a statement.

For the study, researchers administered surveys to more than 5,000 smokers in the United States, Canada and the United Kingdom from 2007 to 2009, and then followed up with them one year later.

Smokers answered a series of questions, including how many cigarettes they smoked a day and how often they noticed warning labels on cigarette packages. Researchers also asked them if warning labels made them think about smoking's health risks, or about quitting and if they actively tried to avoid looking at the warnings.

The researchers then asked if they were considering quitting and, at the one-year follow-up, if they had attempted to quit.

Study participants smoked an average of 17 cigarettes a day and 37 percent reported trying to quit at least once at the one-year follow-up.

Because noticing the warnings may be the first step toward getting smokers to think about and attempt to quit, the research team suggests that policymakers require that warnings be larger and more graphic on cigarette packages and that they are supplemented with mass media campaigns with similar health warnings.

The findings were recently published in the American Psychological Association's journal Health Psychology.