Married couples’ vocabulary sizes align, hinting at selection based on intelligence cues

A study of married couples in the United Kingdom found that marital partners tend to have similar vocabulary sizes. Even after controlling for years of marriage, a substantial correlation between partners’ vocabulary sizes remained, indicating that vocabulary size was likely an important factor in choosing a partner. The paper was published in Languages.

Individuals vary widely in how many different words they know, understand, and use effectively. The total number of words an individual can understand and use in spoken or written language is known as their vocabulary size. Vocabulary size generally grows throughout life, influenced by factors such as education, reading habits, and social environment. Growth is especially rapid in childhood but slows as people reach adulthood.

Adults in societies where their native language is spoken, on average, know tens of thousands of words. People with rich vocabularies tend to have better communication skills, are better able to understand written text, and show more cognitive flexibility in processing language. Vocabulary size might also be a signal that people use when choosing a romantic partner.

Studies indicate that vocabulary knowledge is associated with crystallized intelligence, potentially signaling to partners that an individual might obtain a better education, be more capable of securing resources, or effectively resolve problems—all of which are important factors in partner selection.

The study’s authors, Michael Daller and Zehra Ongun, sought to explore whether vocabulary size plays a role in partner selection. They also wanted to know if this role is the same for both male and female partners, or if it is primarily females who are attracted to male partners with a larger vocabulary. Additionally, they were interested in whether the length of marriage is associated with vocabulary size in marital partners.

The study participants were 83 Turkish-English bilingual married couples living in the U.K. Their marriages ranged in length from 9 to 23 years, and participants were between 27 and 57 years old at the time of the study.

The participants completed assessments of their vocabulary size in both English and Turkish (an X-lex test). The assessments included 100 real words and 20 pseudo or non-words (texts that look like words but have no meaning). The words in the assessment varied in how commonly they are used in everyday communication, with some words being very common and others quite rare.

Results showed that participants with larger vocabulary sizes in English tended to have lower vocabulary sizes in Turkish and vice versa. Marital partners tended to have similar vocabulary sizes; in other words, men with smaller vocabulary sizes tended to be married to women with smaller vocabulary sizes, and the same was true for those with larger vocabulary sizes.

After controlling for years of marriage, this strong similarity in partners’ vocabulary sizes persisted. The study authors concluded that it is not accommodation during the marriage that leads to similar vocabulary sizes but rather that vocabulary size likely played a crucial role at the time of partner selection.

The study authors explained that “intelligence, education, and wealth are important assets for the value of a person on the biological market of partner selection. These psychological and economic traits cannot be judged directly but need to be inferred by a proxy, such as the vocabulary size. Vocabulary size cannot be manipulated at will and is therefore an honest signal for these traits.”

However, they cautioned against overinterpreting their findings, noting that “we acknowledge that it is a massive leap to draw conclusions from the present correlations about a decision-making process years ago when the partners met. However, we still claim that knowledge of infrequent vocabulary, be it productive or receptive, is human capital that is acquired through a lengthy and costly process of education. It is of course only one asset amongst many others that are important in partner selection.”

The study makes a valuable contribution to understanding the intricacies of romantic partner selection. However, the study was conducted on a small group of English-Turkish bilinguals (individuals speaking both languages). Results on other cultural and language groups might not be identical.

The paper, “Size Matters: Vocabulary Knowledge as Advantage in Partner Selection,” was authored by Michael Daller and Zehra Ongun.