Horror or Gothic Fiction is one of the easy genres to spot, and also one of the most fun to explore, as long as you don't mind looking at the hard stuff. Snapped minds, crypt-like spaces, actual crypts, death and dismemberment, fear, the extremes of human behavior, a juxtaposition of the "sacred" and the "profane" – these are some of the sure signs you're in a Gothic story, or at least a Gothic moment.
There are many sub-genres within this genre. In the "supernatural Gothic" supernatural forces (usually connected with the dead and/or the divine) literally cause the scary stuff that happens. In the "explained Gothic" it seems at first like supernatural forces are in play, but, by the end of the story, everything is neatly explained. There's also the "ambiguous Gothic." This is harder to explain, because it's so ambiguous. These stories are open to multiple interpretations, all of which rely on facts outside the story. Nothing in the story really makes sense. We have no "supernatural" or "reasonable" explanation with which to reassure ourselves.
"The Tell-Tale Heart" probably falls in category three. It's been over a hundred years since the story was written, and nobody knows precisely what to make of it, in spite of much study.
Poe's work is often considered part of the "Southern Gothic" tradition. Stories in this genre deal with anxieties and issues related to slavery in the southern U.S., sometimes in a veiled or hidden way. In her book Playing in the Dark: Whiteness and the Literary Imagination, Nobel prize-winning author Toni Morrison argues that the work of Poe does just this, pointing to the short story "The Black Cat" (about a guy who kills his cat) as a prime example.
We think "The Tell-Tale Heart" might fit under that category, too. Check out the narrator's "Character Analysis" for more details.