Language deprivation experiments have been claimed to have been attempted at least four times through history, isolating infants from the normal use of spoken or signed language in an attempt to discover the fundamental character of human nature or the origin of language.
The American literary scholar Roger Shattuck called this kind of research study "The Forbidden Experiment" because of the exceptional deprivation of ordinary human contact it requires. Although not designed to study language, similar experiments on non-human primates (labelled the "Pit of despair") utilising complete social deprivation resulted in serious psychological disturbances.
Throughout history, several rulers have claimed to have carried out this kind of experiment:
An early record of a study of this kind can be found in Herodotus's Histories. According to Herodotus (ca. 485 – 425 BE), the Egyptian pharaoh Psamtik I (664 – 610 BE, i.e. 200 years before Herodotus) carried out such a study, and concluded the Phrygian race must antedate the Egyptians since the child had first spoken something similar to the Phrygian word bekos, meaning "bread". Recent researchers suggest this was likely a willful interpretation of their babbling.
An experiment allegedly carried out by Holy Roman Emperor Frederick II in the 13th century saw young infants raised without human interaction in an attempt to determine if there was a natural language that they might demonstrate once their voices matured. It is claimed he was seeking to discover what language would have been imparted into Adam and Eve by God. The experiments were recorded by the monk Salimbene di Adam in his Chronicles, who was generally extremely negative about Fredrick II (portraying his calamities as parallel to the Biblical plagues in The Twelve Calamities of Emperor Frederick II) and wrote that Frederick encouraged "foster-mothers and nurses to suckle and bathe and wash the children, but in no ways to prattle or speak with them; for he would have learnt whether they would speak the Hebrew language (which he took to have been the first), or Greek, or Latin, or Arabic, or perchance the tongue of their parents of whom they had been born. But he laboured in vain, for the children could not live without clappings of the hands, and gestures, and gladness of countenance, and blandishments."
A few centuries after Frederick II's alleged experiment, James IV of Scotland was said to have sent two children to be raised by a mute woman isolated on the island of Inchkeith, to determine if language was learned or innate. The children were reported to have spoken good Hebrew, but historians were sceptical of these claims soon after they were made.
Critical authors have doubted the veracity of the accounts: probably neither Psamtik I nor James IV ever conducted any such studies, and probably neither did Frederick II. Only Akbar's study is most likely authentic, but offers an ambiguous outcome.
- The "forbidden experiment" occurs in Paul Auster's The New York Trilogy.
- In The Twilight Zone episode "Mute" (1963), several children are raised in such a manner to foster telepathic communication.
- In the Batgirl comic series, the title character, Cassandra Cain, is deprived of spoken language during childhood. This was part of an attempt to create a martial artist with an exceptional ability to interpret body language, as it was believed that this would give one a great advantage in close combat.
- In Le Miroir de Cassandre by Bernard Werber, the title character Cassandre and her older brother are deprived of spoken language during a part of their childhood as an experiment from their mother, a famous paedopsychologist
- Shattuck, Roger (1994) . The Forbidden Experiment: The Story of the Wild Boy of Aveyron. Kodansha International. ISBN 1-56836-048-7.
- Herodotus, History II:2, found in "An Account of Egypt".
- Danesi, Marcel and Paul Perron (1999). Analyzing Cultures: An Introduction and Handbook. Indiana: Indiana University Press, p. 138.
McCulloch, Gretchen (2014). Slate Magazine. "What Happens if a Child Is Never Exposed to Language?"
- Medieval Sourcebook: Salimbene: On Frederick II, 13th Century
- "First Language Acquisition". Western Washington University. Archived from the original on 2017-07-20. Retrieved 2007-02-03.
- Dalyell, John Graham, ed., The Chronicles of Scotland by Robert Lindsay of Pitscottie, vol. 1, Edinburgh (1814) pp. 249-250.
- Davidson, J.P. (2011). Planet word. London: Michael Joseph. ISBN 9780141968933. Retrieved 1 July 2014.
- M. Miles, SIGN, GESTURE & DEAFNESS IN SOUTH ASIAN & SOUTH-WEST ASIAN HISTORIES: a bibliography with annotation and excerpts from India; also from Afghanistan, Bangladesh, Burma/Myanmar, Iraq, Nepal, Pakistan, Persia/Iran, & Sri Lanka, c1200-1750 Archived 2008-02-22 at the Wayback Machine
- Robin N Campbell & Robert Grieve (12/1981). Royal Investigations of the Origin of Language. Historiographia Linguistica 9(1-2):43-74 DOI: 10.1075/hl.9.1-2.04cam
- Wi.Pö. (2000). Waisenkinderversuche (= Orphan Experiments). Lexikon der Psychologie (= Encyclopedia of Psychology). Spektrum Akademischer Verlag, Heidelberg.