Christian Jarrett’s BPS Research Digest Blog has an intriguing post called “Tongue-tied: When bilinguals switch languages involuntarily” that reports on a study on “the case of two bilingual patients who, during the course of brain surgery for epilepsy, appear to have had their ‘switches’ involuntarily flipped”; the conclusion is “These case studies support the notion that, in bilinguals, specific regions at the front of the left hemisphere act as a language switch.” Fascinating stuff. (Thanks, Trevor!)


  1. Next question: Does it also act as a dialect switch? A jargon switch?

  2. Interesting studies being done there. Never knew that it would be as simple as a “switch” (stimulation) that shuts off the language that is not being used.

  3. I wonder what would happen with trilinguals, etc.? I wonder if the “switch” would just suppress their first tongue, leaving the rest all available? (I notice that trilinguals often mix up the second and third somewhat, which makes sense if the brain has a convenient “switch” for suppressing the first tongue but less of a mechanism for suppressing later ones. On the flip side, this mixing-up seems usually to go away once the trilingual is more fluent in the second and third, so maybe that has more to do with the time it takes to build a “switch” for suppressing older languages when learning a new one.)

  4. Actually, I switch 2 dialects in Japanese (my L1). I wonder what happens in this case, as someone has already mentioned above. I am also curious about what happens in morpheme-level interlingual code switching.

  5. As far as switching goes: I developed a working reading knowledge of Chinese 25 years ago, and during some years since then I’ve used it almost every day, and other years almost not at all. What I’ve found is that when I pick it up again after a lapse, it takes me an hour or two to get up to speed. It’s as though the switch itself has to be relearned, before I can actually get back to the Chinese.
    This is a different thing than partly forgetting the language itself. Once I’m up and going, there will be vocabulary items I’ll have to look up that I used to know. But at the beginning it’s my access to the whole language that has been impaired — a holistic impairment which disappears fairly quickly and isn’t a matter of learning everything I’ve forgotten one unit at a time.

  6. Richard Hershberger says

    “What I’ve found is that when I pick it up again after a lapse, it takes me an hour or two to get up to speed.”
    I have the same experience reading Chaucer. I took a class in Chaucer as an undergraduate *mumble mumble* years ago. At first I struggled reading it, but by the end of the class I was nearly perfectly comfortable with it. When I go back now, these few short decades later, I will once again struggle, but only for an hour or two, after which I am once again comfortable with it.

  7. And I’ve known a Russian-speaking lady who’d lived in England for forty years and whose Alzheimer’s disease progressed to such a stage that she she’d forgotten how to speak English, although her husband and children spoke only English.

  8. Code switching is the sign of high intelligence. Amazing how those boundaries of the brain function.

  9. The conclusion implied by the BPS R. Dig. Blog post (that, not talking about any other, I'll be calling simply the post) strays from the experimental findings as described in the very post itself. The facts, I am afraid, were also messed up to a degree. Unfortunately, I access only an abstract for the article (a sesquipedalian link that fetches the abstract is at the end of the post). It is clear, however, that the switching of languages was immediately reversible in both patients, and occurred while they underwent planned, voluntary, scientific (as opposed to medical) tests, made on respective occasions of their crania having been open, and brains exposed (for medical reasons); the post is unclear on this, but not me alone, I suspect, was under an impression that the patients discovered that their first language is now their second one, and vice versa, upon awakening after their surgery. It was not so. In both cases, part of the brain was either “sedated,” or shut down more locally by electricity, while the subjects performed specially crafted tasks involving the use of language (uh, scratch the last line and a half please; the subjects counted aloud and did other silly stuff like that. 🙂 )

    Next, the authors report their conclusion that the observed effect was “not likely the result of a selective inhibition of one language, but the result of a temporary disruption of brain areas that are involved in language switching.” This also implies that there exist such areas. I am not in a position, of course, to comment on an article having read only its abstract. However, it certainly would not have been scientific at all to conclude based only on this experiment with only two test subjects that

    • there existed such areas,
    • their inhibition provoked (not made it harder, as the common sense would suggest!) language switching,
    • the cause was indeed that and not the suppression of activity of a native language physical “quarters” in the brain,
    • other prudently conceivable mechanisms were also not responsible,
    • that every n-lingual person had this area located in the brain not far from or at the same locus as had their m-lingual neighbors.
      the latter statement came not from the abstract but seemed to me to have been implied by the blog post; this is my merely an opinion.

    Therefore, I can only assume that the experiment was planned based on previously available other data, or that there were other data that affected the forging of the final conclusion (or, most likely, both of that was true). But this is where our access to facts about the article ends, sestertiis conservatis, and it shall remain unknown to me how exactly the conclusion has been reached by the researchers.

    There are some implications not supposed to be made: it is better to conservatively hold on what we see, not imagine. They may be true, and some likely are, just not proven. First, there is no implication that the “switch controller” in question is located in the same spot in every healthily developed subject. Second, nothing suggests or denies that this area having evolved to be (or work as) a switching-specialized computer. Weak counter-arguments are that bilinguals are rare enough to affect brain evolution, and that there probably exist data showing the switch area is not idle in unilingual subjects. But there is a danger in accepting such reasoning. Every everything must be experimentally confirmed, no there probably exist or reasonable to think allowed. Brain is a complex system (a pot of boiling water is also one). Both brain and pot are hypothesized to be computationally irreducible, which, if true, means that there is not a computational model encompassing all aspects of brain workings (or turbulent waters) that could require less computations that is performed by the same brain (or pot) itself. We better not intuit, presume, or just know anything conclusive about such systems: once in a while an obvious thing is proven to be wrong; such discoveries are always shocking for they really are counter-intuitive, by the very way this works!

    As for the relations between the brain and the language, the best book out there is The Symbolic Species by Dr. T. W. Deacon, 1997, who is a neurobiologist and an anthropologist: a logical, sequential, easy to understand treatise (I, for one, am not a neurobiologist, and not even close); he remains committedly within his field, and the only, IIRC, time he names languages and mentions syntax features is when he describes peculiar correlation between damage to two well-known brain areas and syntheticity–analyticity of a language. Indeed, he is unlike some even “popular” researchers taking on this problem then swaying as far as from neurophysiology to morphology to the psychology of child education to I grok not that mess of subject matters, inexorably ending up with a crumbling under own weight yet another “united theory of everything.” Up to date, from what I was able to gather, we have either zero or one non-self-contradicting theories that positively explain the origin of symbolic communication; but if only we are lucky to have one already, then it is that that has been formulated in T.S.S.

    Oh, and he wonderfully confirms Burroughs’ notion that language is a virus; not from the outer space hopefully, but still nicely exemplifying symbiosis and co-evolution at work!

  10. marie-lucie says

    About the experience of forgetting then remembering a language, or blurting something in a language different from the one intended: I think most bi- or multilinguals have had this happen at some time. I used to think that nobody could mix up their own with a foreign language, until I caught myself (when a student in the US) addressing my German roommate in French, which she did not understand, instead of English which was our common language of communication. I guess my subconscious said “not English”, and came out with French.
    This sort of thing is not only anecdotal but can have serious practical implications. One case is forgetting a second language, as in the case of the Alzheimer’s patient quoted above. Another concerns the erosion of an endangered language when minority speakers who have been away from their home community come back, having apparently forgotten their native language, and conditions prevent them from recovering it.
    I spent several years in a native community in Canada and have spoken with many native people about language issues. Time and again I have heard stories like “As a child I was sent to hospital and was away for two years, and when I came back I could not speak the language any more, but my parents kept speaking to me and I started to remember it” – this from people over a certain age, whose parents were monolingual in their own language and spoke it to their children as a matter of course. On the other hand, I also heard many stories like “I spoke our language as a small child, but my sister was sent to hospital …., and when she came back she could not speak the language, so we had to switch to English” – this from a younger generation of speakers, growing up in families where the parents were young enough to have become bilingual, and could therefore make the switch. Unfortunately, unless there were monolingual grandparents in the family as well, this switch reinforced the returnees’ (and the other children’s) English but prevented them from relearning the native language, as English had now become the “normal” way of speaking, and as a result the other siblings lost their native fluency as well.
    A memoir written by a missionary who lived in the same area with his family around 1890-1914 (when the language was spoken by the whole population) recounts a similar occurrence: his oldest son was sent to England as a teenager to go to school and was away for a few years. He and his siblings had spoken the native language between themselves and English to their parents. When he came back, he appeared to have totally forgotten the native language and did not even understand it. About 3 weeks after his return, one of his brothers addressed him in this language, saying something like “who do you think you are, can’t you speak like us any more?” and the older brother suddenly started to speak it as fluently as before.

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