While reading The Bell Jar, it was quite apparent, and explicitly stated, that Esther Greenwood  experiences/describes parts of her life in relation to a bell jar.  Esther has ways in which she narrates how the metaphoric bell jar changes her sensorial perceptions: by visual distortion and creating a stifling and soupy feeling/atmosphere for Esther to live and breathe.

The visual distortion plays upon both Esther and the reader. To the reader, Esther could be seen as being confined within the bell jar. Her actions, though seemingly orderly and described calmly, have an underlying sense of oddity and alarm. The way Esther narrates from within the bell jar, she depicts and describes circumstance as nothing special, just ordinary. However, she's using the bell jar's distortion to blur and shroud the unsettling events of Esther's depressive condition. On the other hand,  looking from inside out of the bell jar, Esther feels as though she's watching the world with a view only she sees, and it's isolating*. Everyone sees Dodo Conway as an endearing woman with a lovely family; however, looking at Dodo through the bell jar, Esther is alone* in seeing Dodo as some grossly dehumanized fertility machine.

Esther time in the bell jar wasn't just full of "stifling distortions;" Esther describes being trapped in the bell jar full of "sour air," and equating the confinement of the bell jar to a "bad dream." In difference to distorting Esther's narrations perceptions visually, she is also physically feeling confined and stifled. The moments in which Esther feels free are when she describes being "open to the circulating air" as opposed to trapped in the "stifling air" under the bell jar.

*before meeting Dr Nolan, who shares many of the same progressive views as Esther, etc.