One (of many) employee satisfaction theory state, that the wage is NOT a motivating factor. Training of skills, challenging assignments etc. are all motivating factors, because the employee attain an inner satisfaction through solving the problems and gaining new valuable knowledge. However, the wage is merely a maintaining factor.

It's like a car:
It doesn't run faster because you mount a larger gasoline tank. But if you upgrade the engine it will run faster (maybe even with the same amount of gasoline!!!).