"Araby" by James Joyce and "Cathedral" by Raymond Carver deal with sight and blindness in similar-yet-different ways. "Araby" deals with a young child who becomes so enthralled with his friend's older sister that he overly-romanticizes a trip to the marketplace. On the other hand, "Cathedral" tells the story of a man's experience with—and prejudiced against—a blind man without having had any previous interaction with the blind. Both narrators are "blinded" by their own thoughts and world views, and by the end of the two respective stories, each of them casts off their own illusions and begins to see the error of their judgments.
In Joyce's story, the narrator has constructed an idealized image in his mind of Mangan's sister—and subsequently, of Araby itself. Unfortunately, these romanticized notions pretty much ruin his first experience with both. When he first speaks with her, he becomes confused, does "not know what to answer," and is so engrossed in the fact that he's actually speaking to her that he inevitably forgets what he has said. Because of this, he is not "seeing" this encounter for what it is but rather what he thought it would be. In a sense, he is blinded by his own imagination. By the end of the story, however, this illusion is finally lifted, and he sees Araby for what it is.
Similarly, in Carver's story, preconceived notions of the blind initially confuse the narrator. He doesn't understand why a blind man would sport a beard, believes he read somewhere that blind men don't smoke because "they couldn't see the smoke they exhaled," and becomes speechless at the prospect of Robert owning a television. These thoughts about what a blind person must be like are a contradiction for the narrator, however, as he openly admits that he has "never met, or personally known, anyone who was blind." By the end of the story—with the help of a drawing activity with Robert—the narrator's prejudice against and false notions about blindness are finally lifted; in a great display of irony, he is taught to "see" the world through the eyes of a blind man.
For your assignment, you might want to look at how both narrators are blinded by their own illusions and preconceived notions (as referenced above). You can also investigate ways in which the setting supports the narrow views of the two narrators. For instance, the first sentence of "Araby" describes North Richmond Street as "being blind." This gives the impression that the street is cut off from the world around it, which is mirrored in the narrator's inability to see Araby (the market) for what it truly is. Likewise, "Cathedral" takes place entirely within the narrator's home; though there are descriptions of his wife's experiences many years prior, they are being told from the point of view of the narrator, who is reflecting back while in the comfort of his house. Though it is not clearly spelled out, having the narrator spend the entire story in his own home suggests isolation from the outside world, at least in regard to his lack of knowledge and experience with the unknown (in this case, blindness).