What is the state of the art research of the consciousness level for high-level cognitive activity? Everybody knows situations where activities requiring concentration and high level consciousness can over time become a "background" task.

For example:


you read a text aloud but think about other things
you drive a car but it just "happens" and you can listen to the news


Question: is it measurable to demonstrate how an activity "goes background" in the brain? What is the current state of research, or at least what are proper neuroscience terms to look for in this context?
One approach to this is to search for "habituation", "learned task", "concomitant task", "dual task" and "multiple task" studies, which may include cognitive and physical aspects (memory, reaction time and such). "Background tasks" are usually related to computers.