Which narrative device is used to develop the plot in this passage of The Tell-Tale Heart?

In "The Tell-Tale Heart," Edgar Allan Poe employs the narrative device of unreliable narration to develop the plot. The story is told from the perspective of an unnamed protagonist who insists on their sanity while describing their obsession with an old man's eye and the subsequent murder. This unreliable viewpoint creates tension and suspense, as readers are left questioning the narrator's mental state and the reality of the events unfolding. The intense focus on the narrator's inner turmoil drives the plot forward, culminating in the dramatic reveal of guilt and paranoia.