Once I heard from someone that your mother tongue is the language you talk in your thoughts. I've asked many people to verify the correctness of this proposition and to me, inductively this seems to be true. However, I can't deductively claim it, since I have no reference to be made.

I personally know 4 languages (Persian, Kurdish, English, and reading and listening of French). However, I think in Persian.

I just wonder, can we change our mother tongue? In other words, if we accept the above-mentioned theory for specifying mother-tongue, can we change the language in which we think? I know that I can do it deliberately, and many times I do think in English, but only when I'm conscious, and this tires me out.

However, I'd like to arrive to the point where I can think in English spontaneously. Is it possible? How? What are the techniques?

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    Can you give us the reference that says "your mother tongue is the language you talk in your thoughts"?
    – Louis Rhys
    Nov 4, 2011 at 8:38
  • No @LouisRhys, I don't have any reference. That's why I said that I can't prove it, and I've also included "Is it possible to think in another language" part. :) Nov 4, 2011 at 8:43
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    I don't think one "thinks in a language". For example, normally when someone enters a dark room and decides to switch the lights on, or when he feels hungry and walks to a restaurant, does he think in a particular language? Apparently I don't, except when I consciously choose to articulate it in my thought. Another example would be infants or deaf people who haven't learnt any language. Supposing one thinks in a language, in what language do they think?
    – Louis Rhys
    Nov 4, 2011 at 8:45
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    But many times I come to find myself being dived deep inside my thoughts, and when I become conscious, I realize some conversations I've made while I was unconsciously thinking. Nov 4, 2011 at 11:57
  • Sure, you can converse with yourself, but in my opinion it doesn't mean you think in a language. Sure it involves thinking, but so do conversations with other people. On the other hand. You can think about your chess strategy, how good your dinner is, etc. without involving any language. If you can speak effortlessly in language X I'm pretty sure you can also converse with yourself effortlesly in that language, and if you struggle with speaking it, you will also struggle to do it with yourself. The difference is perhaps your vocal tract doesn't have to participate.
    – Louis Rhys
    Nov 4, 2011 at 16:25

6 Answers 6


I think you already got exhaustive answers to your question. For my part, I would like to point out that your question is based on a false assumption that people think in a particular language. Here's a nice quote for you:

"Most cognitively oriented linguists (e.g. Jackendoff, 1992; Pinker, 1994) argue that humans think in a non-linguistic format (Pinker calls it mentalese) which we map automatically and without conscious control onto the structures of particular languages like English or French. We then use these structures, either in our heads to regulate our thoughts consciously (inner speech), or in the external modalities of speech, writing or sign, for communication with others. You may have had the experience of dreaming in a language you’re learning, and perhaps you can even recall dreamed conversations in it. Again, although these impressions can seem very vivid, they are not evidence that we think in language. We can wrap our thought in language, and this is clearly how we co-construct many of our beliefs about the world with other speakers, as psychologists such as Lev Vygotsky (1986) have pointed out. But this doesn’t mean that language and thought are the same thing." (Hall, Smith, & Wicaksono. 2011. Mapping applied linguistics: A guide for students and practitioners)

  • Right--in cognitive science, we have no clear idea what the commonsense notion of "thinking" might map onto cognitively. Explaining this (if at all possible) would require a complete theory of the nature of language, the mind, and their integration, which we are nowhere near achieving (and yet more problematic, any additional explanation of "consciousness"). Our experience of "thought", an internal "hearing" of language, suggests that maybe all "thinking" is is internal speech. But the flip could be true: maybe speech is just the "verbalization" of thoughts, whatever they are. How to tell? Nov 7, 2011 at 3:04
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    Most psycholinguists will disagree with you. Indeed, there's a strong link between language and thinking. However, they are separate abilities and you don't need language to think. See, for example, a really good textbook by Traxler, M. J. 2011. Introduction to psycholinguistics: Understanding language science. You can also read about double dissociation in any psycholinguistics textbook.
    – Alex B.
    Nov 7, 2011 at 21:46
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    My comment makes it seem like I'm trying to equate the two. I'm not. It will likely turn out that the commonsense notion of "thinking", which seems to be the conscious experience of inner speech, isn't at all like what we think cognition is, like, forms of (conscious or otherwise) higher-order inferential processing of multi-modal information. Of course language and such (extra-linguistic) cognition are non-identical. The questioner isn't really asking about thought in this sense, but about whether their internal speech can spontaneously be coded in other than their native language. Nov 7, 2011 at 23:34
  • a relevant comic Nov 8, 2011 at 23:55

If we accept your definition of mother tongue, then yes, you can switch to other languages, but that's not the definition.

When you're fluent in a certain language, you think in that language, because since languages are never exactly the same, you need to think using other logics to make your sentences have sense. And right now, while I'm typing, I'm thinking in English. But it obviously isn't my mother tongue.

So let's define what a mother tongue is again, this is the mostly agreed definition: it's the language you acquired in the early years of your life through the natural language acquisition in a natural setting (with your family, your village/town/city) and regardless of your following instruction; for these reasons, it's usually also the first language that you acquire.

Considering this definition, you can't change your mother tongue, it's something that doesn't depend on what you do but on your own personal history. However you can reach a high fluency in other languages and that is the key to think in those languages. For example, if you go to another country and live there, after a while you'll acquire the skills to be fluent and you'll treat that language almost as it was your mother tongue. Some people even dream in other languages, not just think in that, but they still have the same mother tongue.

Of course, I wasn't speaking about the situations Louis mentioned, such as turning off the lights, since that doesn't require any language skill, or about deaf people, which are on a different level and I don't have enough knowledge as for now in that field.

  • your definition was fine. Is it formal? Can you give me some references for that? +1 anyway for good point of view. :) Nov 4, 2011 at 11:59
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    I disagree. Fluency means you can speak without stopping and starting. I'm sometimes told I am fluent in Spanish but I definitely am not able to think in Spanish yet and don't know if I will ever be able to. Nov 4, 2011 at 13:41
  • @hippietrail Sorry if I reply this late... Anyway, I think there are different levels of fluency. Certainly I agree with you, fluency means that you speak without stopping, but that's why you think in that language and you don't translate it in your head before speaking. If you "translate something", you're fluent enough but less, not completely.
    – Alenanno
    Nov 5, 2011 at 10:32
  • @SaeedNeamati What do you mean by "formal"? As in official? I guess so, but no doubt someone might disagree. Still, it's the definition most linguists agree with, and by most I mean a high percentage. I don't know what I can link right now, but if I find something, I'll let you know.
    – Alenanno
    Nov 5, 2011 at 10:36
  • @Alenanno: I think a lot of language can be quite formulaic and it's when I'm mostly not called on to go beyond the formulaic stuff that people say I'm fluent. And this formulaic stuff doesn't really require thinking in the language. More a case of filling in the blanks with a bit of pick the right article or ending, which I am as often as not consciously doing if not always to the point of slowing down and thus losing fluency. Nov 5, 2011 at 10:47

As others have answered, this question is based on a weird definition of what a "mother tongue" is. It also seems to presuppose that thought is always articulated in a language, which is far from true (I have no reference for that, but I know for a fact that I generally think directly in concepts rather than words, and I know other people who do as well. I think it's been studied before, but I cannot find a reference to that study at the moment. As far as I remember, there is a sizeable minority of people who think mostly in concepts rather than words).

One thing I think I can add is that even if you take Alenanno's definition of a mother tongue (which is indeed the most common one), there is actually nothing special about one's mother tongue, besides the fact that it was the one learned chronologically first. It's for instance perfectly possible to completely lose command of one's mother tongue later in life. There are lots of examples of people migrating with their families at the age of 6 to 10 (or even later) to another country, completely cutting the link with their original country. By the age of 40 to 50, it's not uncommon for those people to not be able to speak their mother tongue any longer, except maybe for one or two heavily accented words.

My personal experience also agrees with this: I am a French person who moved to the Netherlands 10 years ago. I speak Dutch and English fluently, and much more often than I speak French. And although I still use French regularly (if not that often) and it is my mother tongue, it is not the language I speak best any more! I often struggle trying to find my words when speaking French, and I've been told I developed a Dutch accent when speaking the language (I can't hear it myself). Dutch nowadays comes to me much more naturally than French, and I feel I can express myself far more easily even in English than in French! So although it is my mother tongue, nowadays French is only my third language in terms of fluency.

So to answer your last questions, yes, it is perfectly possible to think spontaneously in another language than your mother tongue (if you think in a language at all!). There is no special technique to reach that point. As kaleissin pointed out, it's purely a matter of fluency: the more you actively use a language (passive use like reading and listening is not enough), the more naturally you'll be able to think in it.


If personal anecdotes are ok, and "thinking in a language" includes internal conversations like "what do I want for dinner today" (introspective people have a never-ending conversation/discussion going in their heads), then I would say I am capable of thinking in both my mother tongue and English, and that I almost manage to think in German when I've been there long enough. What language I think in depends om my surroundings or what I have been reading recently. Since I'm writing this answer in English, I am currently thinking in English. I dream in both my mother tongue and English and sometimes in halting German. I often can't remember the language of some article recently read, I only remember the content.

I would go so far as saying that you aren't really fluent in a language until you can think in it, mentally switch to it completely. If you need to translate in your head you are not fluent. For me, this can make translation quite hard as I know what a word means in one language but lack that word in a different language and so have to resort to circumlocutions and a lot of hemming and hawing and halting explanations :)


I don't have any links or references to back up this answer but since the comments are already overflowing and I don't want it to get lost I'm adding it as an answer...

I am certain that I've read in a popular linguistics book of an extreme case where a man had four first languages with each replacing the previous due to many upheavals in his early life forcing him to be moved to new language communities.

I read this quite some time ago so I'm sure it wasn't on the Internet and was likely to be in a book by David Crystal or some similar writer who makes books on languages accessible to people not trained in linguistics.


First of all I want to mention that it is pretty possible to think in another language(not your mother tongue) spontaneously. I claim that because I experienced that. I used to think (automatically) in German , dream (of course automatically) in german (in my dream i used to talk even to my family and my relatives in German) and my mother tongue got somehow awkward so that it was difficult for me to use correct grammatical structures and appropriate words. I even wasn't so efficient at German and I was in the middle of B1 level when I used to dream in German.(I learnd German from the beginning in Berlin.) I think mother - tongue is a clear phrase and it means the language you have learnt growing up in an environment during the very first years of your life. However, I believe in another term - "first language". I hold an opinion claiming that you are able to have several passive first languages. One of your first languages can become active based on your situation. I think when you "own" a language, it is one of your first languages. I mean having an intuition in the language by "owning" the language. It depends on the manner of learning. Besides, as my experience proofs it has nothing to do with your level in that language.

P. S. To complete the evidences, I got my mother tongue back arround one month after going back to my homeland and after several months studying English in my homeland when I went to Germany again, in a couple of days I was again more comfortable with German and some of the conditions changed to the same as before going to my homeland (and this time my level in German was much lower!).

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