This ability is, of course, impossible. And there would seem little reason to pretend to have it. As such, there are only about a half dozen documented cases of persons claiming to have the ability, or someone making the claim on their behalf. University of Michigan linguist Sarah Thomason analyzed these cases and found them without merit.

In one case, an American woman supposedly spoke Swedish while under hypnosis. Since she used a vocabulary of about 100 words, this initially seemed legitimate (that she was speaking Swedish, not that she was doing it without having heard it before). But more careful research revealed 40 of those words were spoken first by the hypnotist. Another 30 words were cognates, words that have the same etymological origin and may sound nearly the same in two languages. There aren’t a lot of Swedish-English cognates, and that she would have 30 of them ready to rattle off seems to indicate she was speaking English, with it being counted as Swedish by the hypnotist, who was also her husband. The words she supposedly managed were poorly pronounced, but still written down in transcription as if her enunciation were flawless.

Another claim centered on a woman named Gretchen, with German being the language and hypnosis again the method. She mostly just repeated words the hypnotist was saying, changing only the intonation. She also improvised words that sounded German, but were not. Gretchen managed only a miniscule vocabulary with inconsistent pronunciation. Even a better performance wouldn’t have counted, as it was revealed she had prior limited access to German books and television.

The case that appeared to hold the most promise of being genuine came from India. It focused on a woman who was said to be able to speak Bengali without having been exposed to it. Unlike the first two examples, she was speaking the language. It was in a rudimentary but unmistakable fashion, similar to a 3-year-old. But a deeper investigation revealed she had heard the language as a preschooler and had attended an elementary school that taught it to first-graders. By the time her purported xenoglossy was highlighted, she was nearing middle age and seemed to have forgotten about the Bengali lessons from 30 years prior. She wasn’t being fraudulent, but also wasn’t demonstrating xenoglossy.

The best known case is about a girl known only by the pseudonym Rosemary. It is based solely on the works of Dr. Frederic H. Wood and his associate, Howard Hulme. Wood claimed the girl channeled an ancient Egyptian princess and spoke about 5,000 words or phrases, with Hulme jotting away.

All this appeared in a book, with no independent testing or even a confirmation Rosemary existed. Egyptologist Battiscombe Gunn examined the case and determined Hulme to be severely deficient in understanding ancient Egyptian. Any utterance that had even a remote similarity to ancient Egyptian counted as a hit. All this would be like trying to transcribe a Cannibal Corpse song. You would pick up almost nothing, but since you know they’re probably growling about blood and murder you would throw that in there.

The only contemporary case is that of Matěj Kůs of the Czech Republic. He was in a crash and after regaining consciousness, according to his friends, spoke perfect English. By the time the media and scientists showed up, his English was limited to “Go away,” or some such approximation.

Whereas xenoglossy claims are very rare, glossolalia is quite common. This is better known as speaking in tongues. Originally, there were two purported forms of speaking in tongues, both equally implausible. One was a flawless xenoglossy, with the person being able to fluently speak a tongue foreign to them. The other form held that listeners had the power to understand a language they never heard before. This was cited in Acts, with Paul claiming it fulfilled the prophecy in Joel that believers would have this ability in the end days. By my count, that puts us in End Day No. 710,000.

Besides early Christians, ancient Israelis and Apollo worshippers got in on the tongue fun. Today, speaking in tongues consists of strings of gibberish that make Ned Flanders’ ramblings seem eloquent. The speaker will eventually form a very loose pattern of similar sounds and inflections, but it is not a language.

Speakers structure their patterns, perhaps unconsciously, on their surroundings and audience expectations. There are sometimes accompanying physical reactions, also specific to locale. Some convulse, some go limp, while others are trancelike. With the speech being nonsensical, interpreters have a broad range to work with. They hear what they expect a person awash in the spirit to be saying, creating an instance of auditory pareidolia.

A study by psychiatrist Andrew Newberg at the University of Pennsylvania showed that persons speaking in tongues have a steep decline in function in the brain’s frontal lobe, which enables reason and self control. Meanwhile, there is increased activity in the parietal region, which oversees sensory information. This pretty much explains the rolling around on the floor yelping bit.