Oct. 31, 2006 -- What's the best way to convince a teenager that smoking is a great idea? Tell him his parents want him to stop.

That's the rather disturbing suggestion of a study of teens who had watched tobacco-industry-funded television ads urging parents to talk to their children about smoking. The study shows that these teens were more likely to have smoked in the past month and more likely to say that they planned to smoke in the future.

Researcher Melanie Wakefield, PhD, says she suspected reverse psychology was at work. "Any parent knows that telling a teen what to do can cause them to do just the opposite, especially if all you tell them is that they're too young," Wakefield, of the Cancer Council Victoria in Melbourne, Australia, tells WebMD.

Antismoking activists say the study proves that the tobacco industry can't be trusted to produce effective antismoking campaigns. "If Philip Morris was serious about preventing youth smoking, it would support programs run by organizations whose purpose was reducing youth smoking programs, not just pretending to do so," says Stanton Glantz, MD, director of the Center for Tobacco Control Research and Education at the University of California, San Francisco.