Previous studies have shown that watching screen smoking activates parts of the brain involved in craving and reward, but the new research is the first to show that priming for the physical act of lighting up becomes automatic too.
"What's particularly novel about these findings is that viewing movie smoking activated regions involved in understanding and planning actions," says lead author Dylan Wagner of Dartmouth College in Hanover, New Hampshire.
Wagner used an fMRI to scan the brain of 17 smokers and an equal number of non-smokers while they viewed scenes from the film Matchstick Men, which included several clips of actors lighting up. The volunteers were unaware that their reactions to smoking were being analyzed.
Only in smokers did Wagner see activation of parts of the brain vital for goal-directed hand actions, including the anterior intraparietal sulcus and the lateral inferior frontal gyrus. "Moreover, we found that activity in these regions tracked with the hand the smokers use for smoking," he says.
The findings dovetail neatly with the earlier work showing that smokers had increased cravings to smoke after they'd watched movies in which actors had done so."This new study connects the biology to the behaviour, and is a big step forward in our understanding. The question is whether the motion picture industry will keep doing big tobacco's dirty work."
A study in 2003 showed that the movie industry was the biggest factor prompting adolescents to begin smoking. And in 2008, a study revealed that tobacco companies in the 1950s had secretly paid big stars including Clark Gable to promote their products.