How does Edgar Allan Poe use imagery to characterize the narrator of "The Tell Tale Heart"?
The narrator describes the old man's eye with a visual image, saying, "He had the eye of a vulture—a pale blue eye, with a film over it." This image helps us begin to understand what it is that really terrifies the narrator. When he says that the eye is pale blue with a film, it sounds as though the old man might have cataracts, a condition that reduces sight and makes the eye appear filmy. This is also a disease associated with old age. When the narrator describes it as a "vulture" eye, this might make us think of death since vultures prey on carcasses of dead animals. We can begin to surmise that the old man's aged, filmy eye reminds him of death, and because he is so uncomfortable with the idea of death, he wishes to rid himself of the eye: a reminder of the thing he so fears.
The narrator's description of his movements also provides many examples of imagery that help to characterize him. He says,
And every night, about midnight, I turned the latch of his door and opened it—oh so gently! And then, when I had made an opening sufficient for my head, I put in a dark lantern, all closed, closed, that no light shone out, and then I thrust in my head . . . It took me an hour to place my whole head within the opening so far that I could see him as he lay upon his bed. . . . And then, when my head was well in the room, I undid the lantern cautiously—oh, so cautiously—cautiously (for the hinges creaked)—I undid it just so much that a single thin ray fell upon the vulture eye. (emphasis mine)
There are several examples here of tactile, visual, and auditory imagery. The abundance of minute, exact descriptions helps alert us to the narrator's unhealthy state of mind. He insists that he is perfectly sane and healthy, but no sane and healthy person acts the way he does in this passage and nor would such a person likely describe their movements with quite so much imagery and detail.
A fun question. Poe used images throughout the story to characterize the narrator. A few examples can be seen below.
In the first few lines, the narrator uses many images (heaven, hell, etc.) to indicate the breadth of his senses; this also shows his unbalanced mind.
When the narrator describes the eye of the old man, he uses images that show his obsessive nature, as well as his unbalanced perspective. (The "eye of a vulture"!)
At the story's end, when he gives himself away, the images of the sounds heard indicate how nervous and explosive the narrator is becoming.