Why does the narrator makes us of the singular "eyebrow" rather than the plural "eyebrows" in this excerpt from the chapter two of F. Scott Fitzgerald's The Great Gatsby?
“I like your dress,” remarked Mrs. McKee. “I think it’s adorable.”
Mrs. Wilson rejected the compliment by raising her eyebrow in disdain.
“It’s just a crazy old thing,” she said. “I just slip it on sometimes when I don’t care what I look like.”
Body language is often an outside indicator of what people feel on the inside. In The Great Gatsby, by F. Scott Fitzgerald, Myrtle Wilson is not a particularly subtle person; in fact, she is bold enough to meet her lover, Tom Buchanan, right in front of her husband. Myrtle is a sensuous woman, and there is "an immediately perceptible vitality about her as if the nerves of her body were continually smouldering."
She uses her body to communicate, and in this exchange with Mrs. McKee, Myrtle clearly speaks. The two women are at a party at Myrtle and Tom's apartment when Mrs. McKee offers her a sincere compliment on her dress. While a compliment like this may be graciously accepted by someone else, Myrtle is disdainful of it for several reasons.
First, Myrtle is sure she is significantly classier than she really is. Though she has a rich lover, Myrtle consistently demonstrates her lack of class, but that does not affect how she perceives herself. Second, she obviously considers herself (and therefore her taste in clothing) to be much better than anyone at her own party because she is having an affair with an incredibly rich man. What she is with Tom is so much better than what she has with Wilson that Myrtle does not have an accurate perception of who she really is.
Myrtle dismisses Mrs. McKee's compliment both with words of disdain and a lifted eyebrow--a common indicator of condescension and contempt. As a literary device, this simple act enhances our view that Myrtle is a physical (sensual) being. Everything that happens to her later (including Tom's punching her in the nose) is physical, and this is one more way Fitzgerald adds to that characterization.