When Overtones premiered, Sigmund Freud's theories were highly influential. Freud examined how various psychological forces shape an individual, ultimately identifying three primary components of the human psyche: the ego, the id, and the superego. The ego interacts with the outside world through the senses and acts as the "rational" element that mainly guides a person's actions. The id encompasses the instincts for survival and the quest for pleasure and is often viewed as the untamed, primitive side. The superego embodies values and moral principles. Although Freud did not publish The Ego and the Id—the book that clearly defined these concepts—until 1923, he had already extensively discussed the interaction of societal and primal forces on the psyche. These ideas were well-known among educated circles in the United States and influenced many playwrights of the time. They began incorporating elements such as dream analysis, hypnosis, and subconscious states into their works.

Overtones is acknowledged as the first play to physically depict the conflict between the ego and the id. By using a dual-character format, Gerstenberg successfully embodied the internal struggle within each character. At the beginning of the play, she makes it evident to the audience that Harriet and Hetty are actually the same person, with Hetty's opening line, "Harriet. Harriet, my other self. My trained self." Gerstenberg further underscores this dual-character concept by having Margaret and Maggie represent the ego versus id conflict of the other character in the play.

The theme of feminism is subtly woven into Overtones. Although the two characters do not directly address the oppression of women or their restricted opportunities, these concepts become clear through their circumstances. Both Margaret and Harriet blame their dissatisfaction and unfortunate situations on their total dependence on their husbands. They have relied on these men to provide fulfilling lives, yet now, with unmet expectations, they find themselves trapped. Neither woman has the resources to be independent or change her situation. Instead, they see only one solution: to connect with a more successful man who might offer a better life. Harriet longs for John because Charles does not give her enough affection. Margaret seeks Harriet’s wealth and influence because John cannot support her adequately. The notion of working to improve their existing relationships never occurs to them. This perspective reflects the era in which Overtones was written, a time when women were expected to stay at home and follow their husbands' wishes. Like Harriet and Margaret, most women had little social power or influence, leaving them with very few options.

Jealousy plays a central role in Overtones. Each character desires what the other has and is prepared to go to great lengths to achieve it. Through the conversations between Maggie and Hetty, Gerstenberg exposes the deep-seated jealousy simmering beneath the surface. When Hetty boldly states, "I'm going to take him away from you," and Maggie counters with, "I want your money—and your influence," their intense envy and desperation become clear. Margaret's jealousy is also symbolically depicted through her clothing. As highlighted in Gerstenberg's opening stage directions, "Harriet's gown is a light, 'jealous' green."

The Victorian era technically refers to the time when Queen Victoria governed England, lasting from 1819 to 1901. Victorianism captures the social norms and customs prevalent during her reign. Although Queen Victoria's rule concluded more than a decade before Overtones was penned, many Victorian ideals remained apparent in the United States during Gerstenberg’s era. In a typical Victorian household, the husband was the leading figure, acting as the "breadwinner," while the wife was expected to stay at home to look after the children. Instilling proper behavior and social etiquette was considered essential. People were expected to maintain decorum at all times, and any display of uncontrolled emotion was discouraged. The tradition of afternoon tea became popular during this time. Victorianism is sometimes associated with arrogance and a sense of superiority. Overtones portrays a strong sense of Victorianism in the exchange between Margaret and Harriet during tea. Despite their internal emotional struggles, they strive to uphold a delicate and proper facade, fervently trying to hide their true feelings.