Statement of intention to do something should not predict behaviour unless accompanied by evidence of 'wanting' or 'needing' to do it.

Smokers who report that they intend to stop smoking soon are more likely to make a quit attempt in the next 3 or 6 months even when they do not report wanting to. This appears to conflict with the theory and suggests either that intentions can influence behaviour independent or that when smokers reported that they intended to do stop soon in many cases they did not feel that they also needed to report that they wanted to (Smit e al, 2010 manuscript submitted for publication). This needs further examination.

Statements that one 'should' do something (evaluation) will fail to predict behaviour unless accompanied by statements or other evidence that one 'wants' or 'needs' to do it (motive).

Forty percent of smokers in England say they 'ought' to stop smoking while 29% say they 'want' to. Only those who say they want to  are more likely to go on to make a quit attempt in the following 3 or 6 months (Smit et al, 2010: paper submitted for publication).