The story depicts the effect of under-stimulation on the narrator's mental health and her descent into psychosis. With nothing to stimulate her, she becomes obsessed by the pattern and colour of the wallpaper. "It is the strangest yellow, that wall-paper! It makes me think of all the yellow things I ever saw – not beautiful ones like buttercups, but old foul, bad yellow things. But there is something else about that paper – the smell! ... The only thing I can think of that it is like is the colour of the paper! A yellow smell."

 

In the end, she imagines there are women creeping around behind the patterns of the wallpaper and comes to believe she is one of them. She locks herself in the room, now the only place she feels safe, refusing to leave when the summer rental is up. "For outside you have to creep on the ground, and everything is green instead of yellow. But here I can creep smoothly on the floor, and my shoulder just fits in that long smooch around the wall, so I cannot lose my way."

 

The 'Yellow Wallpaper' is driven by the narrator's belief that the wallpaper is alive. At first it seems merely unpleasant: it is ripped, soiled, and an “unclean yellow.” The worst part is the apparently formless pattern, which fascinates the narrator as she attempts to figure out how it is organized. After staring at the paper for hours, she sees a ghostly pattern behind the main pattern, visible only in certain light. Eventually, the sub-pattern comes into focus as a desperate woman, constantly crawling, looking for an escape from behind the main pattern, which has come to resemble the bars of a cage. The narrator sees this cage with the heads of many women, all of whom were strangled as they tried to escape. Wallpaper is domestic and humble, and Gilman skillfully uses this nightmarish, hideous paper as a symbol of the domestic life that traps so many women.