Two studies investigated how cultural context and familiarity impact lexical access in Korean-English bilingual and English monolingual adults. ERPs were recorded while participants decided whether a word and picture matched or not. Pictures depicted versions of objects that were prototypically associated with North American or Korean culture and named in either English or Korean, creating culturally congruent and incongruent trials. For bilinguals, culturally congruent trials facilitated responding but ERP results showed that images from both cultures were processed similarly. For monolinguals, culturally incongruent pairs produced longer RTs and larger N400s than congruent items, indicating more effortful processing. Thus, an unfamiliar culture impeded linguistic processing for monolinguals but facilitated it for bilinguals familiar with that culture. Study 2 presented images that were more or less familiar and both groups replicated the pattern for monolinguals in Study 1. Therefore, in Study 1 monolinguals responded to familiarity but bilinguals responded to culture.
Purpose:
Conversion rates from mild cognitive impairment (MCI) to Alzheimer disease (AD) were examined considering bilingualism as a measure of cognitive reserve.
Methods:
Older adult bilingual (n=75) and monolingual (n=83) patients attending a memory clinic who were diagnosed with MCI were evaluated for conversion to AD. Age of MCI and AD diagnoses and time to convert were recorded and compared across language groups.
Patients:
Patients were consecutive patients diagnosed with MCI at a hospital memory clinic.
Results:
Bilingual patients were diagnosed with MCI at a later age than monolingual patients (77.8 and 75.5 y, respectively), a difference that was significant in some analyses. However, bilingual patients converted faster from MCI to AD than monolingual patients (1.8 and 2.8 y, respectively) resulting in no language group difference in age of AD diagnosis. This relationship held after accounting for education, cognitive level, immigration status, and sex.
Discussion:
The findings suggest that greater cognitive reserve as measured by language status leads to faster conversion between MCI and AD, all else being equal.
Attention is required during speech perception to focus processing resources on critical information. Previous research has shown that bilingualism modifies attentional processing in nonverbal domains. The current study used event-related potentials (ERPs) to determine whether bilingualism also modifies auditory attention during speech perception. We measured attention to word onsets in spoken English for monolinguals and Chinese-English bilinguals. Auditory probes were inserted at four times in a continuous narrative: concurrent with word onset, 100 ms before or after onset, and at random control times. Greater attention was indexed by an increase in the amplitude of the early negativity (N1). Among monolinguals, probes presented after word onsets elicited a larger N1 than control probes, replicating previous studies. For bilinguals, there was no N1 difference for probes at different times around word onsets, indicating less specificity in allocation of attention. These results suggest that bilingualism shapes attentional strategies during English speech comprehension.
In the absence of effective pharmacological interventions for the prevention of dementia, attention has turned to lifestyle factors that contribute to cognitive reserve. Although cognitive reserve cannot prevent the occurrence of disease, the trajectory is different for high reserve and low reserve patients, giving more time for independent living to high reserve individuals. We argue that lifelong bilingual experience meets the criteria for an experience that confers cognitive reserve, although neural reserve, a related concept, is more difficult to validate. Bilingual patients show symptoms at a later stage of disease and decline more rapidly than comparable monolingual patients. These patterns are considered in terms of evidence from behavioural, imaging and epidemiological studies. Finally, the role of bilingualism in protecting against symptoms of some forms of dementia are discussed in the context of other protective factors and the limits of this reserve approach in dealing with the consequences of dementia.
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