Simultaneous bilingualism
[2] Wölck has pointed out that there are many "native bilingual communities", typically in South America, Africa, and Asia, where "monolingual norms may be unavailable or nonexistent".
[9] Despite these findings, many therapists and other professionals maintain that simultaneous bilingualism can be harmful for a child's cognitive development.
Bilinguals appear to acquire the same milestones—including when they say their first word, when they say their first telegraphic phrase, and when they obtain a vocabulary of fifty words—within the "normal range of variation" of monolingual development in each language.
Furthermore, increasing the number of people children interact with in each language will provide them with more opportunities to learn in varied contexts.
[17] Study has provided evidence against the popular "one-parent-one-language" approach, as it restricted the contexts a child had for interactions and use of that language.
[25] Varying contexts of exposure provide more opportunities for bilingual children to learn more words.
[29] Some linguistic experts, dating from the early 20th century, have maintained that the best way to facilitate bilingual acquisition is to have each main input carrier (usually parents) use one and only one language with the child.
De Houwer points out that input may be separated by situation: for example, "Finnish spoken by all family members inside the home but Swedish once they are outside.
The parents' expectations and knowledge about language development can be instrumental in raising simultaneously bilingual children.
[32] The attitudes of the child's extended family and friends have been shown to affect successful bilingualism.
Languages that are deemed more useful or more important will dominate the bilingual mental lexicon while the less valued ones will not be acquired as fully.
The child is fully bilingual This "unitary language system hypothesis" has been the subject of much debate in the linguistic world.
Furthermore, research indicates that children form separate phonemes and phonological rules for different languages.
[42] The study of simultaneous bilingualism supplements general (monolingual) theories of child language acquisition.
[10] However, it has proven difficult to compare monolingual and bilingual development, for a number of reasons: Meisel claims "there is no reason to believe that the underlying principles and mechanisms of language development [in bilinguals] are qualitatively different from those used by monolinguals.
[46] Meisel proposed in a 1990 article that "bilinguals tend to focus more on formal aspects of language and are therefore able to acquire certain grammatical constructions faster than many or most monolinguals.
"[47] One area of language acquisition that has been studied extensively is the use of the disambiguation heuristic, which is the tendency by children to "associate a novel word with a novel object".
Byers‐Heinlein & Werker (2009) studied 48 17 and 18-month-old monolingual (English), bilingual, and trilingual (22 diverse languages) infants to compare their patterns on disambiguation.
Byers‐Heinlein & Werker (2009) hypothesized that this was particularly an effect of translation equivalents (knowing the name for something in more than one language), as "they represent a departure from the one-to-one mapping between word and concept that is typical of monolingual vocabularies" (p 820).
Indeed, in a later study conducted by Byers-Heinlein & Werker (2013) in 17–18 month-old Chinese-English bilingual infants, results showed that disambiguation did not occur in the infants who "understood the translation equivalents for more than half of the words in their vocabularies" (p. 407), while disambiguation occurred in those who knew fewer translation equivalents.
They also suggested that the reverse could be possible—that infants who employed the heuristic were the ones that did acquire the translation equivalents because of the high level of one-to-one mapping.
Findings suggest that the amount of activation that occurred cross-linguistically was related to the similarity between the translation equivalents of the languages.
[55] Many have suggested that bilinguals have weaker connections in their lexical representations than monolinguals (Bialystok, Luk, Peets, & Yang, 2010; Ameel, Malt, Storms, & Van Assche, 2009).
[55] The findings of cross-lingual activation can be used as support for a model of interconnectivity of a bilingual individual's languages in their mental lexicon.
Processing Rich Information from Multidimensional Interactive Representations (PRIMIR) This model suggests one integrated phono-lexical system that is organized based on the different characteristics of language input.
This lack of cost for code switching is especially used because they argue that separate lexicons would cause a slower reaction time, which was not indicated in the findings.
Though simultaneous bilingual children learn two languages at once, this does not mean that they speak both with identical competence.
Researchers approaching dominance as "relative language proficiency" adopt measures such as mean length of utterance (MLU),[62][60] upper bound (UB), percentage of multimorphemic utterances (MMUs), lexical access, and lexicon size.
Bilingual children most often engage in intra-sentential code-switching, switching languages in the middle of a sentence.
[57] Taeschner found that bilingual children prefer to insert elements of the other language rather than use simplified forms.
