It is probable that humans remember unfinished/incomplete tasks better than completed tasks. I am wondering if there is a genre/style of literature which takes advantage of this to boost the memorability of stories by leaving none of the threads tied up. I know that there is no proper way to define "unfinished", especially if an author has decided that their work is 'finished', so to clarify a little further, I've drawn some diagrams (because everybody loves diagrams).
Generally I imagine that over the course of a novel various threads (goals, threats, characters) can make up the ark of the story.
Often the threads are resolved by the climax and then there is some kind of denoument. Sometimes not every thread is resolved, for example in Norwegian Wood where
it is left ambiguous whether Toru and Midori get back together
Sometimes threads are created and then lost/drift away/are never tied up, for example almost every plotline in A Series of Unfortunate Events.
And then of course sometimes extra threads get resolved after the climax of a story, like the "there's just one thing I still don't understand..." type endings of a detective story.
To be a 'Zeigarnik book' I would say that all of the plot-lines would be left unresolved, and the result is the appearance (or reality) of a book where the author got half way and then gave up.
In this case there is no resolution of anything, rather than a cliff-hanger as such. I suppose another analogy could be watching a single episode of a soap opera, where there is no sense of the character stories terminating.
Is this a real genre or style of book that anybody is familiar with?