Symbolism, Imagery, Allegory
Scholars have made a lot of the fact that the narrator starts referring to the wallpaper as "the paper." Given that the narrator has a repressed literary bent, it's no great stretch of the imagination to posit that the (wall)paper becomes her text.
After all, the narrator is forbidden from writing at all, because her husband/doctor doesn't want her to journal about being sick:
I did write for a while in spite of them; but it does exhaust me a good deal—having to be so sly about it, or else meet with heavy opposition.
I sometimes fancy that in my condition if I had less opposition and more society and stimulus—but John says the very worst thing I can do is to think about my condition, and I confess it always makes me feel bad. (1.17 – 1.18)
Her intellect restrained from reading and writing, the narrator’s mind instead turns to her surroundings and settles upon the wallpaper as a source of intellectual stimulus. And sure, we guess the wallpaper is stimulating...in a disassociated, hallucinatory sort of way.