A good definition of mental models and a very thorough article explaining the process of learning via declarative and procedural ways. However, I wonder if the learning is hierarchical and time spaced as well. e.g. when you first learn to drive, it is fast learning about gear shifting, lane change, speed, distance etc. It is a declarative model till you keep on practising driving and then over the period of time, it becomes automatic. It gets burned with your basal ganglia and you no longer consciously decide every action during driving. This is slow learning. Almost every learning follows this part from declarative to procedural.