A study published in The Quarterly Journal of Experimental Psychology by Radvansky, Krawietz, and Tamplin, suggests that a "memory episode" is some kind of contextual placeholder grouping recollections, such that a new episode — something as simple as walking through a doorway — makes it harder to remember all the details associated with the previous episode. 

This might be a useful thing for design; it might help a user remember something if you can figure out what's associated with its memory episode.