WASHINGTON, Oct. 28 (Xinhua) -- A new study published in the latest journal Tobacco Control showed that pictorial warnings like images of diseased body parts and testimonials from real people were the most effective features at getting smokers to quit.

"Humans act in response to our emotions," said the paper's lead author Jazmyne Sutton with the University of Pennsylvania. "When we feel a negative emotion, fear, disgust, etc, we want to avoid the source of that emotion."

To analyze the various features used in pictorial warning labels, the researchers collected more than 300 warning labels from various sources.

They used pictorial warning messages on cigarette packs in Australia, Canada, New Zealand, and the United Kingdom; pictorial warning messages proposed by the U.S. Federal Drug Administration that have not been implemented; a set of anti-smoking messages produced by tobacco companies; testimonial pictorial warning messages developed for an experimental study; and pictorial ads used in various local and national campaigns.

The researchers identified 48 objective features that could be present in the ads, including factors like image color, photo type, presence of male or female characters, presence of medical equipment, and argument type.

They then recruited nearly 1,400 current smokers to view the ads and answer questions about how the ads affected them.

"A wide variety of studies from different countries show that pictorial warning labels are effective in curtailing smoking behavior," said the paper's senior author Joseph N. Cappella at Pennsylvania. "Our work seeks to isolate some of the specific elements that enhance and retard effectiveness to help guide future message designs."