Nielsen's "Usability" and Some Questions (Part 1/3)

What is usability?
One of the key concerns for Usability professionals is being able to answer the question “What is Usability?” According to Jakob Nielsen, usability can be defined by the following five attributes: learnability, efficiency, memorability, errors, and satisfaction. Each of these attributes would seem obvious once you read the list of them, but, of course, being able to come up with a complete and concise list is the difficult part. For each of these attributes, he then further explicates the details. In the case of learnability, I’m glad that Nielsen has differentiated between novice and expert users. However, he does not necessarily include level of comfort in mastering an interface. Holding usability to a higher standard would involve taking learnabilty to the level of mastery and a high degree of comfort. Currently “learning software” is the strongest bastion for these more stringent levels of learnability.
One question for this section would be:
How does one use leading edge teaching techniques to increase cognition and make learnability more core to usability?