The wallpaper in the ñThe Yellow Wallpaperî by Charlotte Perkins Gilman symbolizes the narrators´s mental state in the story.
The narrator projects her own feeling of being trapped and her desire to escape onto the woman creeping behind the wallpaper.
The woman behind the wallpaper represents the narrator's repressed self that she pictures as a prisoner in the domestic sphere of her life. Thewoman manifests the narrator's repression, her submission to the seduction of insanity represented by the yellow color of the wallpaper.