Maybe it could be used to see what negative ideas people have that aren't obvious? A kind of control group? Though if we already know the parts of the brain that "light up" when shown negative images, I guess we already know that...

Idek. Maybe the article is oversimplifying, and the actual goal of the study is to see what parts of the brain are directly responsible for addiction and how they react. The researcher's quote about how smokers keep smoking because they feel good about it does not give me hope that they understand anything about addiction, though. Also, 30 people sounds like a very small study.