Crash course:
Learning 0 - responding to a specific context in a way that is reliable/fixed.
Learning 1 - having the ability to vary your responses to repeated exposures to a context.
Learning 2 - The ability to perceive contexts, and transfer learning across contexts.
Learning 3 - (I guess) the awareness of contexts in a way that allows you to step outside of and critically evaluate them.
It's all pretty confusing and that's probably at least a little wrong. Interesting notion though.