[1] Experiments involving language deprivation are very scarce due to the ethical controversy associated with it.
[2] Similarly, experiments were performed by depriving animals of social stimuli to examine psychosis.
Genie, 13 years of age upon discovery, was malnourished, insensitive to tactile senses,[clarification needed] and silent even upon being evoked;[clarification needed] however she had proper social skills and she was able to maintain eye contact with caregivers, giving the impression that she understood instruction.
After being discharged from the hospital she was put in foster care where she received "informal" training.
Genie was capable of discriminating affirmation from negative, comparative adjectives, and colour words.
After four years of language stimulation, her linguistic performance was similar to that of a normal two-year-old infant.
[3][4] An alleged case of language deprivation was of Kaspar Hauser, who was said to have been kept in a dungeon in Germany until the age of 17 and claimed he'd only received contact from a hooded man not long before his release.
Further examination of Anna determined that she was very poor physiologically but that her senses were intact.
Confined to a room with a deaf and mute mother, she spent 6½ years in silence without any language stimulation.
Dr. Jean Marc Gaspard Itard conducted training over a period of 5 years, during which time Victor was able to recover some speech.
[10] Deaf children who do not have access to fluent language models could be at risk of permanent, irreversible effects to their brains.
These effects include not only a detrimental impact on language acquisition, but other cognitive and mental health difficulties as well.
[13] While most deaf infants who receive cochlear implants and auditory therapy early in life will achieve spoken language skills on par with their hearing peers, this effect is not universal; without appropriate supports, or in children with complicating medical conditions, those with cochlear implants exposed only to spoken language can still show a lack of spoken language ability when compared to hearing peers.
[17] Evidence has shown that learning language during critical period will provide native-like abilities in morphology, phonology, and syntax.
Evidence has demonstrated that it can affect language development including morphology, phonology, and syntax.