It has often been said that people can speak in languages that were not formerly known to them. Arguably the most often recited example of this is in the context of demonic possession. For example, those supposedly possessed by malevolent spirits apparently can and regularly do speak in languages they do not know — so often has this happened that it is evidently one of the four criteria typical for "demonic possession":

True demonic or satanic possession has been characterized since the Middle Ages, in the Rituale Romanum, by the following four typical characteristics:[9][10][11]

  1. Manifestation of superhuman strength.
  2. Speaking in tongues or languages that the victim cannot know.
  3. Revelation of knowledge, distant or hidden, that the victim cannot know.
  4. Blasphemous rage and an aversion to holy symbols or relics.

For whatever reason, it is usually Latin. In any case, the key feature is that it is a language unknown to the supposedly possessed speaker, and the phenomenon is called xenoglossia (not to be mistaken for glossolalia, or speaking in tongues, or bilingual aphasia being the transposition of linguistic competence).

The ability to speak in languages previously unknown to a speaker seems to be a testable hypothesis, particularly with modern day recording technology.

Just for clarity, here is a citations defining the claim:

Xenoglossia: Xenoglossia is the sudden and abrupt ability to speak in multiple languages (2). It is imperative that the demonologist look for signs that back up the fact that the suspected victim of demonic possession did not have prior knowledge of such languages or any kind of fluency in the languages exhibited before denoting the appearance of multiple language usage as an indication of possession. It should be noted that in some reported cases of mental illness, an individual can present the ability to suddenly speak in previously unlearned languages. Instances of savantism and genius should also be ruled out before xenoglossia is deemed a sign or symptom of demonic possession.

Is there any evidence regarding the existence of this phenomenon?

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    Has anyone ever been possessed? There is an unconfirmed case of a person in Croatia waking up from a coma speaking fluent German. Read more about Foreign Accent Syndrome on Wikipedia.
    – oosterwal
    Jul 31, 2013 at 0:24
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    @oosterwal I would also add that the phenomenon of bilingual aphasia is a well documented medical condition that arises from brain damage to the area of the brain where ones first spoken language is contained, which is a different area of the brain from second languages. As a result of damage to the area where the first language is controlled the area controlling the second language(s) "kicks in". As damage (e.g. hemorrhaging) subsides, the first language may recover. In any case, it doesn't qualify here because the second language would have been known to the affected person. Jul 31, 2013 at 12:55
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    @rob The question doesn't ask about demonic possession. It asks if xenoglossia has happened, thereby satisfying the "criteria" of "so called" demonic possessions". All Brian is saying is that xenoglossia is a criteria that some people use to detect demonic possessions, but isn't asking us to examine the latter.
    – user5582
    Jul 31, 2013 at 15:48
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    Opera singers regularly sing in languages they do not know. I do not know if this is the answer the OP was looking for but that does exist.
    – Neil Meyer
    Oct 28, 2013 at 10:02
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    The claim is "[some] people can speak in languages that were not formerly known to them". That is a claim, and it is notable. There exist many people that believe it is true.
    – user5582
    May 5, 2014 at 16:58

1 Answer 1


There's a case report A case of secondary personality with xenoglossy from 1979 where the Indian woman in question developed a secondary personality which spoke fluent Bengali, a language the family did not speak. However, the fact that the subject worked at a university makes one very suspicious as to what resources she had available to her. So, a single case report from searching PubMed hardly constitutes scientifically confirmed.

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