Editing Language acquisition (section)

==Representation in the brain==
Recent advances in functional [[Functional neuroimaging|neuroimaging technology]] have allowed for a better understanding of how language acquisition is manifested physically in the brain. Language acquisition almost always occurs in children during a period of rapid increase in brain volume. At this point in development, a child has many more neural connections than he or she will have as an adult, allowing for the child to be more able to learn new things than he or she would be as an adult.<ref>{{cite web|last=Nadia|first=Steve|title=Kid's Brain Power|url=http://www.riggsinst.org/brainpower.aspx|access-date=2016-05-01|archive-url=https://web.archive.org/web/20190630074057/http://www.riggsinst.org/brainpower.aspx|archive-date=2019-06-30|url-status=dead}}</ref>

===Sensitive period===
{{main|Sensitive periods#Language|Critical period hypothesis}}
Language acquisition has been studied from the perspective of [[developmental psychology]] and [[neuroscience]],<ref name="White 2013">{{Cite journal  | last1 = White | first1 = EJ. | last2 = Hutka | first2 = SA. | last3 = Williams | first3 = LJ. | last4 = Moreno | first4 = S. | title = Learning, neural plasticity and sensitive periods: implications for language acquisition, music training and transfer across the lifespan. | journal = Front Syst Neurosci | volume = 7 | pages = 90 | year = 2013 | doi = 10.3389/fnsys.2013.00090 | pmid = 24312022 | pmc = 3834520 | doi-access = free }}</ref> which looks at learning to use and understand language parallel to a child's brain development. It has been determined, through empirical research on developmentally normal children, as well as through some extreme cases of [[language deprivation]], that there is a "[[sensitive period]]" of language acquisition in which human infants have the ability to learn any language. Several researchers have found that from birth until the age of six months, infants can discriminate the phonetic contrasts of all languages. Researchers believe that this gives infants the ability to acquire the language spoken around them.  After this age, the child is able to perceive only the phonemes specific to the language being learned. The reduced phonemic sensitivity enables children to build phonemic categories and recognize stress patterns and sound combinations specific to the language they are acquiring.<ref>{{cite journal |vauthors=Kuhl P, Stevens E, Hayashi A, Deguchi T, Kiritani S, Iverson P|title= Infants show a facilitation effect for native language phonetic perception between 6 and 12 months |journal=Developmental Science |volume=9 |issue=2 |pages=F13–F21 |date=February 2006 |doi=10.1111/j.1467-7687.2006.00468.x |pmid=16472309 }}</ref> As Wilder Penfield noted, "Before the child begins to speak and to perceive, the uncommitted cortex is a blank slate on which nothing has been written. In the ensuing years much is written, and the writing is normally never erased. After the age of ten or twelve, the general functional connections have been established and fixed for the speech cortex." According to the sensitive or critical period models, the age at which a child acquires the ability to use language is a predictor of how well he or she is ultimately able to use language.<ref>{{cite book |last1=Pallier |first1=Cristophe |chapter=Critical periods in language acquisition and language attrition |pages=155–168 |chapter-url=http://www.pallier.org/papers/Pallier.critical.period.attrition.chapter.2007.pdf |editor1-last=Köpke |editor1-first=Barbara |title=Language Attrition: Theoretical Perspectives |date=2007 |publisher=John Benjamins Publishing |isbn=978-90-272-4144-3 }}</ref> However, there may be an age at which becoming a fluent and natural user of a language is no longer possible; Penfield and Roberts (1959) cap their sensitive period at nine years old.<ref>{{cite book |last1=Penfield |first1=Wilder |last2=Roberts |first2=Lamar |title=Speech and Brain Mechanisms |date=2014 |publisher=Princeton University Press |isbn=978-1-4008-5467-7 |page=242 }}</ref> The human brain {{em|may}} very well be automatically wired to learn languages, but this ability does not last into adulthood in the same way that it exists during childhood.<ref>{{cite book |doi=10.21832/9781853597596 |title=Language Acquisition |date=2004 |last1=Singleton |first1=David |last2=Ryan |first2=Lisa |isbn=978-1-85359-759-6 }}{{page needed|date=December 2024}}</ref> By around age 12, language acquisition has typically been solidified, and it becomes more difficult to learn a language in the same way a native speaker would.<ref>{{cite journal |last1=Al-Harbi |first1=Salwa Saeed |title=Language development and acquisition in early childhood |journal=Journal of Education and Learning (EduLearn) |date=8 November 2019 |volume=14 |issue=1 |pages=69–73 |doi=10.11591/edulearn.v14i1.14209 |doi-access=free }}</ref> Just like children who speak, deaf children go through a critical period for learning language. Deaf children who acquire their first language later in life show lower performance in complex aspects of grammar.<ref>{{cite journal |last1=Newport |first1=Elissa L. |title=Maturational Constraints on Language Learning |journal=Cognitive Science |date=January 1990 |volume=14 |issue=1 |pages=11–28 |doi=10.1207/s15516709cog1401_2 |doi-access=free }}</ref> At that point, it is usually a second language that a person is trying to acquire and not a first.<ref name="Sakai, 2005"/>

Assuming that children are exposed to language during the critical period,<ref>{{cite book |last1=Purves |first1=Dale |last2=Augustine |first2=George J. |last3=Fitzpatrick |first3=David |last4=Katz |first4=Lawrence C. |last5=LaMantia |first5=Anthony-Samuel |last6=McNamara |first6=James O. |last7=Williams |first7=S. Mark |title=Neuroscience |edition=2nd |date=2001 |publisher=Sinauer Associates |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK11007/ |chapter=The Development of Language: A Critical Period in Humans }}</ref> acquiring language is almost never missed by cognitively normal children. Humans are so well-prepared to learn language that it becomes almost impossible not to. Researchers are unable to experimentally test the effects of the sensitive period of development on language acquisition, because it would be unethical to deprive children of language until this period is over. However, case studies on abused, [[language deprivation experiments|language-deprived]] [[feral child|children]] show that they exhibit extreme limitations in language skills, even after instruction.<ref>{{cite book |author=Curtiss, Susan |title=Genie: a psycholinguistic study of a modern-day "wild child" |publisher=Academic Press |location=Boston |year=1977  |isbn=978-0-12-196350-7 |oclc=3073433}}</ref>

At a very young age, children can distinguish different sounds but cannot yet produce them. During infancy, children begin to babble. Deaf babies babble in the same patterns as hearing babies do, showing that [[babbling]] is not a result of babies simply imitating certain sounds, but is actually a natural part of the process of language development. Deaf babies do, however, often babble less than hearing babies, and they begin to babble later on in infancy—at approximately 11 months as compared to approximately 6 months for hearing babies.<ref name="Schacter, 2011">{{cite book |last1=Schacter |first1=Daniel L. |last2=Gilbert |first2=Daniel T. |last3=Wegner |first3=Daniel M. |title=Psychology |chapter-url=https://archive.org/details/psychology0000scha |chapter-url-access=registration |trans-title=Second Edition |edition=Second |orig-year=2009|year=2011 |publisher=Worth Publishers |location=United States of America |pages=[https://archive.org/details/psychology0000scha/page/351 351–352] |chapter=9 |isbn=9781429237192 }}</ref>

Prelinguistic language abilities that are crucial for language acquisition have been seen even earlier than infancy. There have been many different studies examining different modes of language acquisition prior to birth. The study of language acquisition in fetuses began in the late 1980s when several researchers independently discovered that very young infants could discriminate their native language from other languages. In ''Mehler et al. (1988)'',<ref>{{cite journal|last1=Mehler|first1=Jacques|last2=Jusczyk|first2=Peter|last3=Lambertz|first3=Ghislaine|last4=Halsted|first4=Nilofar|last5=Bertoncini|first5=Josiane|last6=Amiel-Tison|first6=Claudine|title=A precursor to language acquisition in young infants|journal=Cognition|volume=29|issue=2|pages=143–178|doi=10.1016/0010-0277(88)90035-2|year=1988|pmid=3168420 }}</ref> infants underwent discrimination tests, and it was shown that infants as young as 4 days old could discriminate utterances in their native language from those in an unfamiliar language, but could not discriminate between two languages when neither was native to them. These results suggest that there are mechanisms for fetal auditory learning, and other researchers have found further behavioral evidence to support this notion. Fetus auditory learning through environmental habituation has been seen in a variety of different modes, such as fetus learning of familiar melodies,<ref>{{cite journal |last1=Hepper |first1=PeterG. |title=Fetal 'Soap' Addiction |journal=The Lancet |date=June 1988 |volume=331 |issue=8598 |pages=1347–1348 |doi=10.1016/S0140-6736(88)92170-8 |pmid=2897602 }}</ref> story fragments (DeCasper & Spence, 1986),<ref>{{cite journal|last1=DeCasper|first1=Anthony|last2=Spence|first2=Melanie|title=Prenatal maternal speech influences newborns' perception of speech sounds.|journal=Infant Behavior and Development|date=1986|volume=9|issue=2|pages=133–150|doi=10.1016/0163-6383(86)90025-1}}</ref> recognition of mother's voice,<ref>{{cite journal |last1=Kisilevsky |first1=Barbara S. |last2=Hains |first2=Sylvia M.J. |last3=Lee |first3=Kang |last4=Xie |first4=Xing |last5=Huang |first5=Hefeng |last6=Ye |first6=Hai Hui |last7=Zhang |first7=Ke |last8=Wang |first8=Zengping |title=Effects of Experience on Fetal Voice Recognition |journal=Psychological Science |date=May 2003 |volume=14 |issue=3 |pages=220–224 |doi=10.1111/1467-9280.02435 |pmid=12741744 }}</ref> and other studies showing evidence of fetal adaptation to native linguistic environments.<ref>{{cite journal |last1=Moon |first1=Christine |last2=Cooper |first2=Robin Panneton |last3=Fifer |first3=William P. |title=Two-day-olds prefer their native language |journal=Infant Behavior and Development |date=October 1993 |volume=16 |issue=4 |pages=495–500 |doi=10.1016/0163-6383(93)80007-U }}</ref>

Prosody is the property of speech that conveys an emotional state of the utterance, as well as the intended form of speech, for example, question, statement or command. Some researchers in the field of developmental neuroscience argue that fetal auditory learning mechanisms result solely from discrimination of prosodic elements. Although this would hold merit in an evolutionary psychology perspective (i.e. recognition of mother's voice/familiar group language from emotionally valent stimuli), some theorists argue that there is more than prosodic recognition in elements of fetal learning. Newer evidence shows that fetuses not only react to the native language differently from non-native languages, but that fetuses react differently and can accurately discriminate between native and non-native vowel sounds (Moon, Lagercrantz, & Kuhl, 2013).<ref>{{cite journal|last1=Moon|first1=Christine|last2=Lagercrantz|first2=Hugo|last3=Kuhl|first3=Patricia|title=Language experienced in utero affects vowel perception after birth: A two-country study.|journal=Acta Paediatr|date=2013|volume=102|issue=2|pages=156–160|doi=10.1111/apa.12098|pmid=23173548|pmc=3543479}}</ref> Furthermore, a 2016 study showed that newborn infants encode the edges of multisyllabic sequences better than the internal components of the sequence (Ferry et al., 2016).<ref>{{cite journal|last1=Ferry|first1=Alissa|last2=Fló|first2=Ana|last3=Brusini|first3=Perrine|last4=Cattarossi|first4=Luigi|last5=Macagno|first5=Francesco|last6=Nespor|first6=Marina|last7=Mehler|first7=Jacques|title=On the edge of language acquisition: inherent constraints on encoding multisyllabic sequences in the neonate brain.|journal=Developmental Science|date=2016|volume=19|issue=3|pages=488–503|doi=10.1111/desc.12323|pmid=26190466}}</ref> Together, these results suggest that newborn infants have learned important properties of syntactic processing in utero, as demonstrated by infant knowledge of native language vowels and the sequencing of heard multisyllabic phrases. This ability to sequence specific vowels gives newborn infants some of the fundamental mechanisms needed in order to learn the complex organization of a language. 
From a neuroscientific perspective, neural correlates have been found that demonstrate human fetal learning of speech-like auditory stimuli that most other studies have been analyzing{{clarify|reason="most other studies" is vague; this clause is not particularly in the tone of an encyclopedia |date=January 2020}} (Partanen et al., 2013).<ref name="ReferenceA">{{cite journal|last1=Partanen|first1=Eino|last2=Kujala|first2=Teija|last3=Näätänen|first3=Risto|last4=Litola|first4=Auli|last5=Sambeth|first5=Anke|last6=Huotilainen|first6=Minna|title=Learning-induced neural plasticity of speech processing before birth|journal=Proceedings of the National Academy of Sciences|date=2013|volume=110|issue=37|pages=15145–15150|doi=10.1073/pnas.1302159110|pmid=23980148|pmc=3773755|bibcode=2013PNAS..11015145P|doi-access=free}}</ref> In a study conducted by Partanen et al. (2013),<ref name="ReferenceA"/> researchers presented fetuses with certain word variants and observed that these fetuses exhibited higher brain activity in response to certain word variants as compared to controls. In this same study, "a significant correlation existed between the amount of prenatal exposure and brain activity, with greater activity being associated with a higher amount of prenatal speech exposure," pointing to the important learning mechanisms present before birth that are fine-tuned to features in speech (Partanen et al., 2013).<ref name="ReferenceA"/>

[[File:Language Acquisition Phases.png|thumb|The phases of language acquisition in children]]