NEW YORK: Even when they realise how much money they have smoked away with cigarettes and how vulnerable their health could be owing to smoking, some people find it very hard to kick the butt.
Researchers believe they now know why.
During the research, those who exhibited the weakest response to rewards like prospect of saving money or improving health were the least willing to refrain from smoking, even when offered money to do so.
The findings could predict the effectiveness of a reward-based strategy as motivation to quit smoking.
"We believe that our findings may help to explain why some smokers find it so difficult to quit smoking," said Stephen Wilson, an assistant professor of psychology at Pennsylvania State University in the US.
Potential sources of reinforcement for giving up smoking may hold less value for some individuals and, accordingly, have less impact on their behaviour, Wilson explained.
For the study, researchers recruited 44 smokers between ages 18 and 45.
All reported that they smoked at least 10 cigarettes a day for the past 12 months.
Smokers who could not resist the temptation to smoke also showed weaker responses in the ventral striatum when offered monetary rewards while in the functional magnetic resonance imaging (fMRI), the findings showed.
"The striatum is part of the so-called reward system in the brain," Wilson noted.
It is the area of the brain that is important for motivation and goal-directed behaviour - functions highly relevant to addiction.
The study appeared in the journal Cognitive, Affective and Behavioral Neuroscience.