It’s time to talk about gender—why things go wrong with gender in machine translation and what people do about it. Some languages have gendered nouns (German), some have gendered almost everything (Czech, French) and some only few pronouns (English). Let’s say you want to translate sentence: “My doctor told me to stay at home.” into a language that has gendered nouns. A machine translation system is likely to translate the English word “doctor” as a male doctor because male doctors are just more frequently mentioned in the training data than female doctors. Machine translation usually works on the sentence level, so even if the gender is clear from a broader textual context, the system has no chance to use that context. As long as the MT systems are not aware of a broader context, they just need to guess—and the safest guess is always the most frequent option.

Alas, things can get worse. Let’s have a look at what Google Translate does with the following sentence:

The doctor asked the nurse to help her in the procedure.

English → Czech Lékař požádal zdravotní sestru, aby jí pomohla v tomto

English → German Der Arzt bat die Krankenschwester, ihr bei dem Eingriff zu

English → French Le médecin a demandé a l'infirmiere de l'aider dans la

The word “doctor” is so heavily associated with the male gender that even in a sentence where the pronoun “her” clearly indicates that we are talking about a female doctor, the automatic translation is still “Der Arzt” and “Le médecin”.

Machine translation models learn from authentic data that human society generates for other purposes than training machine translation. The training procedure attempts to maximize the probability of the training data given the model. When looking at the model outputs, it seems that maximizing the probability of the data involves also making highly stereotypical associations. This gives us, in fact, a sad message about our society (rather than about machine translation).

By the way, if the doctor is pretty, it is suddenly a different story, the gender gets fixed:

La jollie médecin a demandé a l'infirmiere de l'aider dans la

A paper from this year’s ACL called Evaluating Gender Bias in Machine Translation shows plenty of such examples (the one I showed here is kind of borrowed from the paper) of this problem and introduces an evaluation methodology to tackle gender bias in machine translation. They prepared the evaluation data for 8 language pairs and tested them 6 commercial machine translation systems. All of them turned out to be extremely biased.

Given how strongly gender stereotypes are present in texts that people produce, it makes de-biasing of the models quite a challenging problem. One attempt to fix this issue is presented in a paper that appeared on arXiv last week and will be presented at EMNLP later this year. The title of the paper is Getting Gender Right in Neural Machine Translation. The authors work with the Europarl corpus which consists of the proceedings of the European Parliament. Because we can easily find out who said what in the parliament, we can also tell what was the gender of the speaker. If the machine translation model is trained with this additional information as the encoder’s input, it allows the models to correctly resolve gendered nouns and pronouns related to the speaker. The obvious drawback of this method is that it only works for the domain of EU parliamentary addresses, but with little effort, it is surely applicable for simultaneous interpreting as well.

BibTeX Reference

    title = "Evaluating Gender Bias in Machine Translation",
    author = "Stanovsky, Gabriel  and
      Smith, Noah A.  and
      Zettlemoyer, Luke",
    booktitle = "Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics",
    month = jul,
    year = "2019",
    address = "Florence, Italy",
    publisher = "Association for Computational Linguistics",
    url = "",
    doi = "10.18653/v1/P19-1164",
    pages = "1679--1684",