At a guess, I would say: looking for recurring patterns in fiction, and extrapolating principles/tropes. It's a very bottom-up approach to literature, taking special note of subversions, inversions, aversions, etc, as opposed to the more top-down academic study of literature that loves to wax poetic about "universal truths" while ignoring large swaths of stories (such as Sci Fi and Fantasy) that don't fit into their grand model. Quite frankly, from my perspective, it seems they tend to force a lot of stories into their preferred mold, falling prey to True Art tropes.