Word embeddings trace a 1945 turning point in Japan’s gendered language

Japanese text written between 1900 and 1998 carries a measurable record of how words became associated with women or men, and that record shows a sharp divide opening around 1945. A study published in EPJ Data Science trained a series of yearly word embeddings on historical Japanese corpora to track gender stereotypes across the prewar and postwar eras. The analysis found that associations linking women to work and politics reversed direction after 1945, while associations linking women to the home stayed essentially unchanged across the entire century.

The researchers, Shintaro Sakai, Haewoon Kwak, Jisun An and Akira Matsui, built their measure from the geometry of word embeddings. Each yearly model places words in a high-dimensional space where cosine similarity reflects how closely two words are used in similar contexts. To quantify gender association, the team computed the difference between a word’s cosine similarity to female-related attribute words and its similarity to male-related attribute words. A strongly negative value marks a word as male-associated in the discourse of that year; a strongly positive value marks it as female-associated. Because the models were trained separately on text from each year, the measure yields a trajectory of stereotype strength over time rather than a single snapshot.

The trajectories were examined across three domains that have traditionally been strongly gendered: Home, Work and Politics. The results were not uniform. In the Home domain, female stereotype values remained stable across the decades, with no statistically significant changes detected. In the Work and Politics domains, by contrast, the female stereotype values showed significant trend reversals around 1945. Before that year, the trends ran negative, indicating that words in these public domains were drifting toward male association in the discourse. After 1945, the trends turned positive, indicating increasing female associations in public domains over the postwar decades.

The timing of the reversal is central to the study’s interpretation. The observed changes in the Work and Politics domains are temporally aligned with postwar institutional transformations, including reforms carried out under the U.S.-led Allied Occupation. The authors describe the shift as uneven: the public-facing domains of discourse moved substantially while the domestic domain showed more limited change. This pattern suggests that the language surrounding women’s roles in work and politics responded to the reorganization of Japanese institutions after the war, even as the language surrounding the home remained comparatively fixed.

To probe the Work domain more finely, the researchers extended the analysis to 18 individual occupations and tracked how the gender stereotype value of each occupation word changed over the century. They then compared these embedding-based measures against an external benchmark: official statistics on the proportion of women employed in each occupation. The two measures correlated moderately and positively, with a correlation coefficient of r = 0.364. In other words, occupations with a higher share of women in the real workforce tended to carry more female-associated meanings in the text, indicating that the embedding-based stereotype measure mirrored demographic shifts to a meaningful extent.

The method rests on a well-established principle in computational linguistics: word embeddings encode patterns of co-occurrence, so a word’s position relative to gendered attribute words reflects how that word is actually used in the surrounding text. By training one model per year, the approach converts this contextual usage into a time series. The gender stereotype value, defined as the difference in cosine similarity to female versus male attribute words, therefore functions as a quantitative index of gendered cultural discourse for each year in the corpus.

The study’s scope is defined by its data and method. It measures associations in written Japanese text, not the beliefs or behavior of individuals, and its findings concern discourse rather than direct attitudes. The Home domain result is a null finding over time: female stereotype values there showed no statistically significant change, which the authors contrast with the significant reversals found in Work and Politics. The occupation-level correlation, while positive, is moderate, meaning the embedding measures track real demographic participation only partially.

The article was published on 18 August 2026 as an open access research paper, and the version shared at publication is a peer-reviewed, accepted manuscript carrying a permanent DOI, subject to further edits before the final Version of Record. Within its first days it had recorded 98 accesses. The work contributes to a growing body of research that uses historical text and embedding methods to quantify social change, here applied to one of the most consequential institutional ruptures of twentieth-century Japan: the transition from the prewar period through war defeat to the postwar order under Occupation-era reforms.

The overall picture that emerges is one of asymmetric change. Female associations in words related to work and politics moved from negative prewar trends to positive postwar trends, a reversal the authors date to around 1945 and align with the period’s institutional transformations. Female associations in words related to the home held steady. And at the level of individual occupations, the language of the era followed the demographic facts of women’s participation closely enough to register a moderate positive correlation, suggesting that the gendered texture of Japanese public discourse did respond, unevenly but measurably, to the changing place of women in society.

Subject of Research: Quantifying the evolution of gender stereotypes in Japanese text from 1900 to 1998 using yearly historical word embeddings across the Home, Work and Politics domains.

Article Title: Gendered cultural discourse in Japan across the prewar–postwar transition: evidence from historical word embeddings

Article References: Sakai, S., Kwak, H., An, J., & Matsui, A. (2026). Gendered cultural discourse in Japan across the prewar–postwar transition: evidence from historical word embeddings. EPJ Data Science. https://doi.org/10.1140/epjds/s13688-026-00688-5

Image Credits: AI Generated

DOI: 10.1140/epjds/s13688-026-00688-5

Keywords: gender stereotypes, word embeddings, Japan, prewar-postwar transition, Allied Occupation, historical corpora, occupations, women in workforce, cultural discourse, cosine similarity, EPJ Data Science, computational linguistics