Smit, E. S., Fidler, J. A., & West, R. (2011). The role of desire, duty and intention in predicting attempts to quit smoking, Addiction, 106(4), 844-851. doi:10.1111/j.1360-0443.2010.03317.x

Aims: Motivation to quit smoking predicts quit attempts, although little is known about the role played by its different aspects. This study assessed the predictive value of desire, duty and intention to quit, three different aspects of motivation.
Design: A longitudinal study was conducted involving a nationally representative sample of smokers assessed at baseline and 3 and 6 months later. Baseline assessment took place by face-to-face computer-assisted interviews; follow-up assessments by postal questionnaires.
Setting: England.
Participants: From April 2008 to June 2009, a total of 5593 adult smokers were recruited; 1263 were followed-up at 3 months and 1096 at 6 months.
Measurements: Three dichotomous measures of motivation to quit (wanting to quit, believing one ought to quit, intention to quit soon) were taken at baseline. Whether a subsequent quit attempt was made was recorded at 3- and 6-month follow-up.
Findings: More smokers believed they ought to quit smoking than wanted to or intended to soon (39.0, 29.3 and 23.5%, respectively). Desire and intention were independent predictors of quit attempts at both follow-ups, whereas combining them did not add predictive value and duty was not a predictor. While the predictive value of desire or intention alone disappeared when accompanied by duty, their combination was robust against its negative effect.
Conclusions: Desire and intention independently positively predict quit attempts, while duty appears to mitigate their effect. It would be worth monitoring all three aspects of motivation when evaluating the impact of smoking cessation interventions on motivation to quit.