Strength of Will

[arahant]

Anyone know of any research into variation in strength of will/volition? Perhaps there is some sort of normed scale somewhere?
I guess what I'm talking about is the 'ability' of the rational/discursive part of the brain to 'impose its will' over 'baser' instincts (sorry for all the quotes [img]/images/graemlins/smile.gif[/img] ).
Would there be some way ahead of time, for example, to predict which people would have an easier time kicking addictions?

I often hear people say things like "You just have to decide to quit smoking" or "Just quit thinking about her" or whatever...seems like there must be some measurable variation in the ability to do things that we rationally think are 'right'.