Bilingualism is the regular use of two fluent languages, and bilinguals are those individuals who need and use two (or more) languages in their everyday lives. A person's bilingual memories are heavily dependent on the person's fluency, the age the second language was acquired, and high language proficiency to both languages. High proficiency provides mental flexibility across all domains of thought and forces them to adopt strategies that accelerate cognitive development. People who are bilingual integrate and organize the information of two languages, which creates advantages in terms of many cognitive abilities, such as intelligence, creativity, analogical reasoning, classification skills, problem solving, learning strategies, and thinking flexibility.
History
One of the first researchers on the subject of bilingual memory and representation was linguist Uriel Weinreich. Languages in Contact, an essay published by Weinreich in 1953, proposed a model of bilingual memory organization that made the theoretical distinction between the lexical and conceptual level of representation. Three different types of organizational models were proposed: coordinate, compound, and subordinate, each having a different relationship between the lexical and conceptual levels of representation. In 1954, Ervin and Osgood reformulated Weinreich's compound-coordinate representational model and placed further emphasis on the context of language learning, similar to the encoding specificity principle later proposed by Tulving in the 1970s. In 1984, Potter et al. proposed the hierarchical model of bilingual memory, consisting of two memory structures, the word association model and concept mediation model. The word association model proposes a link between languages at the lexical level while the concept mediation model proposes a direct link between the conceptual representation and the lexical representation in each language. The hierarchical model was later revised by Kroll and Stewart in 1994 to account for linguistic proficiency and direction of translation, since then it has been subsequently revised.
Biological basis of bilingual memories
One of the processes involved in analyzing which neural regions of the brain are involved in bilingual memory is a subtraction method. Researchers compare what has been impaired with what is functioning regularly. This contrast between the destroyed and intact regions of the brain aids researchers in discovering the components of language processing. It has been found that under typical circumstances, when multiple languages are lost at the same time, they are usually regained in the same fashion. It is therefore presumed that areas of the brain, which are responsible for processing language, are potentially the same. There have been examples of cases where languages have been restored prior to one another and to a greater degree, but this is fairly uncommon. The techniques allowing researchers to observe brain activity in multilingual patients are conducted whilst the subject is simultaneously performing and processing a language. Research has proposed that the entire production and comprehension of language is most likely regulated and managed by neural pools, whose stations of communication are in the cortical and subcortical regions. It has been shown that there are no grounds on which to assume the existence of distinct cerebral organization of separate languages in the bilingual brain. That is to say, the cerebral regions that are engaged for both languages are the same. Although neurologists have a basic understanding of the underlying neural components and mechanisms of bilingual language, further research is necessary in order to fully understand or conclude any other findings. Neuroimaging techniques such as fMRIs have shown that at least four brain areas are involved in bilingual switching: dorsolateral prefrontal cortex, inferior frontal cortex, anterior cingulate, and supramarginal gyrus. It is expected that switching from one language to another should involve different functional processes when compared to the brain of an individual who only speaks one language. However further studies on brain activation during this switching of languages needs to be done.
Bilingual episodic memory Episodic memory is closely related to semantic memory. Tulving created the two categories as a way to distinguish the specific knowledge from the general knowledge. Episodic memory contains the records of unique events which occurred at particular times. Particularly, autobiographical memories are stored in the episodic memory. The episodic memory holds the events from personal experiences in the past, exists in subjective time and space, requires a conscious recollection and a controlled process. Tulving referred to this as "mental time travel", and he "classifies encoding as an event, rather than a process".
It is suggested that bilinguals that have better control of their language processing should perform better in episodic than semantic memory tasks. Bilinguals store the input of language exceedingly well, regardless of their intention to learn. Language forms a surface in the progressive retrieval of features of an event (e.g., on College Ave, at Tim Hortons, on Tuesday...), that triggers further forms within the same language serving to guide retrieval. The events, objects, characters, etc. are all cued by linguistic elements that might serve as a series of triggers. This information is highly integrated; the superiority of action memory is due to better episodic integration for action memory (vs verbal); we remember events based on language cues and these cues further solidify the events.
To test episodic memory researchers usually use items that can be related to normal everyday life, such as sentences. Language recognition depends somewhat on the retrievability of meaning, but the extent of this dependence is unknown. Retrieval of memories is language-specific, it matches the language spoken at the time. Depending on what language is used, what is recalled may be different because a cue can activate many meanings. It is the context that conditions what meaning is considered first, and context can change over language and cultures.
Bilinguals also tend to be bicultural, it is known that we filter all of our experiences through culturally shaped scripts. So, those that are bilingual (for the most part bicultural) have multiple scripts to draw from, or more than one set of narrative constraints. All experiences imply some sort of narrative structure, and narrative traditions are culturally shaped. They direct our perception of reality and the encoding of memories. Though they may not directly determine their perception of reality, they determine "how the story is told" which may be different from "how it happened". This shapes memory, as stories that are deemed as worthy to be told are further solidified by the retelling and reliving of the experience.
Bilingual autobiographical memory
Autobiographical memory is a type of episodic memory process which is involved in the recall of one's life experiences and personal events of ones past. Bilinguals have the ability to recall some life experiences in one language, and other events using another. When recalling language information it is important that the language is recalled in the same context as it was encoded. This is referred to as context-dependent memory Ex. If one who is bilingual were to learn a Spanish song in a Spanish speaking country, and then come back to their native land, they would have difficulty remembering the song. However once they were immersed in a Spanish context again, recall would come with much more ease. Research has shown that autobiographical memories have increased availability in the language they were created in. That is to say, memories are richer and more elaborate when recalled in the language that the event has taken place, rather than the other language available to them. This can also be referred to as the encoding specificity principle, where memories appear to be encoded in a language-specific manner. Earlier memory events that occur during youth and are encoded in the first and dominant language, are more emotionally charged, have a higher quality of detail and are greater in number than those memories recalled in the second language. It can also be argued that the language that is spoken and recalled more frequently, will have more associations to multiple circumstances and is therefore more likely to be remembered. Problems can arise if a language that comes to mind 'internally' is not the language that is being spoken externally. For example, if someone recalled an event in Spanish, but then reported it in English. This changeover in languages is most likely to do with the content of the memory itself. Evidence has been shown that language-specific recall of information when probed or cued in the matching language, is recalled vividly, and with much more elaboration and detail. It has also been shown that each language that a bilingual possesses, may represent experiences in somewhat different fashions.
Bilingual working memory
Working memory is an active part of the memory system that temporarily stores and processes information during mental operations. Highly related are the concepts of attention and executive control. A major function of the working memory system is the retention and processing of verbal information. Baddeley's model of working memory suggests the phonological loop, a slave system that is responsible for the rehearsal of verbal information and has been implicated in language acquisition.
Measures of verbal working memory are predictive of proficiency in a second language and working memory capacity is strongly correlated with first and second language abilities. Despite these correlations, research into the effects of bilingualism on working memory have been largely inconclusive. Bilingual performance on working memory tasks can be affected by language dominance, language proficiency, and the nature of the task, variables which can be difficult to control and assess. However, most recent research suggests that there are no differences between monolingual and bilingual individuals in regards to working memory performance, although more research is still required to make any conclusive claims. The evidence suggests that working memory performance has a stronger relationship with general linguistic proficiency than it does with the acquisition of a second language. It has also been observed that there are no significant cross-language differences within bilinguals, providing further support for the hypothesis that working memory is not language specific. Bilingual speakers are, however, more accurate in assessing their metalinguistic reading and working memory abilities compared to monolingual speakers.
Digit span
Research has found that there are cross-linguistic differences on a short-term memory test known as the digit-span task. For example, Chinese speakers as compared to English speakers had a greater digit span. An explanation of this observation is that digits in English take longer to say and subvocally rehearse in the phonological loop, a component of Baddely's model of working memory. It has been suggested that because memory for short words is better than for long words, a phenomenon known as the word-length effect, that there are cross-linguistic differences on the digit span task. This difference has also been observed in Welsh-English bilinguals, who rated themselves as more proficient in Welsh but had a greater digit span in English because of the shorter digit names. However, research has suggested that familiarity and long-term memory may play an important role and that differences are not strictly the result of subvocal rehearsal rates.
Inner speech