How long does knowledge of foreign languages last?

Recent press reports have talked about new research, claiming to show that people retain knowledge of foreign languages learnt many years ago, even if they do not use the language actively. Those reports were triggered by announcements by the researchers, for example at:

In this post, I give a bit more detail on the research. It was a pilot study, intended to lay the foundation for future research. The study is summarised in a paper The final frontier? Why we have been ignoring second language attrition, and why it is time we stopped, by Monika S. Schmid, published in the journal Language Teaching. The other members of the team carrying out the pilot study were Florence Myles and Ángel Osle (University of Essex).

I summarise below:

  • the nature of the research
  • the results of the research
  • some of the other comments in the paper

Nature of the research

The research relied on a web-based survey of native speakers of English who had studied French at secondary schools in England between 1 and 50 years ago to either GCSE level (about age 16) or A-Level (about age 18). Participants:

  • took a vocabulary test presenting 20 real French words and 10 invented words designed to look like they could be French words. Participants indicated which words were real French words
  • took a grammar assessment asking 30 multiple-choice questions (supplying 4 answers for each question).
  • gave a self-assessment of what level their French had reached, both at the end of their school course and at the time of the survey. 

Results of the research

Here is a summary of the results I found most striking:

  • Unsurprisingly, participants who started French younger perform better on grammar than those who started later, but the vocabulary test did not detect such an effect.
  • Rather puzzlingly, participants who finished studying French longer ago scored higher on both the grammar and vocabulary tests. Indeed, most of the highest scoring A-level students had completed their A-level more than 20 years ago. One possible explanation could be that more recent students might not have become so proficient by the end of their studies, but research would be needed to assess whether this is the case.
  • Unsurprisingly, participants scored better on the grammar and vocabulary tests if they regard themselves as having been talented and diligent students of French.
  • Unsurprisingly, participants generally felt their French had deteriorated.  The responses suggested that participants assessed their own proficiency as:
    (a) declining very steadily over time for the first 20 years after they finished studying French;
    (b) holding steady between 20 and 30 years; and
    (c) declining again after 30 years, but more slowly than in the first 20 years.
  • Participants reported that their proficiency had declined less in the post-instruction period if they: are exposed to French often; enjoyed their classes at school; and regard French as a useful and beautiful language. Nevertheless, these factors did not affect grammar and vocabulary scores—except that frequent use of French accompanied a small (and surprising, perhaps spurious) decrease in vocabulary score.

High ability (without exposure) does not protect against decline

Some research on loss (‘attrition’) of people’s first languages (LI) has suggested that when a person has little or no exposure to their first language, people with high linguistic aptitude may retain their first language better than people with lower linguistic aptitude.

Testing this finding, this pilot study found that, among participants with little exposure to French:

  • participants who regard themselves as having been more talented and diligent students of French assessed their own proficiency as declining more slowly than was the case for those who regard themselves as having been less talented and diligent; but
  • the grammar and vocabulary tests did not, in fact, show them as more proficient.


The survey found no evidence that participants who studied French several decades ago know less French vocabulary and grammar than those who studied it much more recently. Nor did the survey find any evidence that this knowledge erodes, even without practice.

But the survey did not test whether participants could use their knowledge in more active tasks, such as understanding language and producing it.

Some of the other comments in the paper

Sections 5 and 6 of the paper present and discuss the pilot study and its results. Sections 1-4 give an overview of what is known, and what is not known, about second language (L2) attrition.  I summarise some things that I found interesting in sections 1-4:

  • knowledge of language is resilient
  • reactivating knowledge of a foreign language
  • previous research on L2 attrition

Knowledge of languages is resilient

According to the paper, virtually all the cumulative data on either first language (L1) attrition or L2 attrition suggests that knowledge of languages is astonishingly resilient. Although knowledge of a foreign language declines to some extent between 3 and 6 years after training ceases, ‘the remainder is immune to further losses for at least a quarter of a century, and much of that content survives for fifty years or longer’.

This resilience is perhaps because:

  • unlike other school-learned subjects such as maths or history, linguistic knowledge contains an implicit /procedural component, which is more resistant to erosion than explicit/declarative knowledge.
  • foreign language skills continue to receive some (indirect) stimulation simply through using the native language.

Other points on resilience

Some of the other points the paper makes on resilience:

  • Early studies suggested that grammar tends to be more stable than vocabulary in foreign language attrition. But teaching styles have changed since those studies and now focus on acquiring communicative skills, rather than explicit learning of grammatical rules and translation into the child’s first language. Grammatical skills acquired implicitly may be more resilient against deterioration.
  • Other things being equal, younger children learn foreign languages more slowly than older children or adults. But it is not known whether these age-related differences in learning make language knowledge more resilient or less resilient.

Reactivating knowledge of a foreign language

There are some indications that attrition of a language arises from knowledge becoming less accessible, rather than from the knowledge disappearing being erased entirely:

  • people may be able to judge a word or structure as grammatical (or ungrammatical) when it is presented to them, yet unable to produce it spontaneously.
  • people can often reuse a foreign language in an emergency, or when they are re-immersed in that linguistic environment.

Because the knowledge does not disappear, it is easier to re-learn a foreign language (and then retain it) than to learn it from scratch. So, efforts are needed to understand how best to help former learners retrieve this knowledge. Simply expecting them to use language classes or apps devised for the first-time learner may not be good enough.

Previous research on L2 attrition

Research into L2 attrition suffers from the shortcomings pointed out for first language attrition research two decades ago—a lack of empirical evidence, of theoretical frameworks and of methodological coherence. Those shortcomings are compounded by problems specific to L2 attrition research.

There has been little research into instructed foreign language knowledge—language skills acquired in the classroom with no significant immersion experience. Past research in L2 attrition has been in immersive settings, including:

  • school learners of a community minority language;
  • simultaneous and early bilingual children;
  • adolescents whose parents have returned to their country of origin after an extended stay in another linguistic environment;
  • former Study Abroad university students ; and
  • the very specific experience of Latter Day Saints missionaries from the US. They who typically receive short, but intensive instruction in a language followed by 2-4 years in that linguistic environment. They then often stop using the foreign language entirely upon their return to the US.

Research in those contexts gives some insights into how language develops in immersion contexts and is then retained. Those insights may not generalise to the most frequent setting of L2 attrition: language instruction in the classroom in the home country, with little other exposure to the language, and followed by years of little or no use. This setting is likely to result in lower proficiency levels and entrench the language less, compared with immersion contexts. The resulting knowledge is more vulnerable to erosion when instruction ends.

Resource on language attrition

Monika Schmid has a website Language attrition at

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