John Updike’s 1968 novel Couples provides the central literary and thematic parallel for The Shampoo Effect. Set in the fictional Boston suburb of Tarbox, a thinly veiled version of Ipswich, Massachusetts, where Updike lived, Couples explores the interlocking adulterous affairs of a group of upper-middle-class friends. The book became a national sensation and a local scandal, as residents of Ipswich recognized themselves and their neighbors in the characters, whose secret lives were suddenly exposed. Updike wrote often about rural American towns, exploring the tension between Protestant morality and the undercurrent of sexual revolution brought about by scientific advances such as birth control. In Couples, this was especially the case, as the book was noted for its explicit sexual content, rare for fiction of the time. Though Updike would eventually deny that Tarbox was modeled on Ipswich in the local paper, residents of the town felt that their secret lives had been exposed, causing their famous author neighbor to eventually move away to the neighboring Beverly Farms (Landrigan, Dan. “John Updike in ‘Couples’ Titillated America With Tales of His Neighbors.” New England Historical Society, 2026). 

The epigraph of The Shampoo Effect is a direct quote from Couples, signaling its influence. In the former, the literary icon Palmer Preston is a clear stand-in for Updike; he’s a celebrated author who lived in the fictional Greenhead (Ipswich) and won a Pulitzer Prize. His most famous novel, Tarbox, is referenced by name, solidifying the connection to Updike. When Caroline, a writer living in Greenhead on a fellowship sponsored by Preston’s foundation, feels betrayed by Van’s circle, she writes a revealing short story about them for The New Yorker. Her editor even pitches the story with the logline, “In Greenhead, Massachusetts, Palmer Preston’s Tarbox is alive, but marriage might be dead” (236). This context frames Caroline’s controversial decision as a direct engagement with Preston’s literary legacy, forcing the reader to confront the same questions about art, betrayal, and the writer’s responsibility that surrounded Updike decades earlier.