Lexically linked domains in language allow a speaker to formulate incompatible rules. How should they be represented theoretically? We argue that a speaker has a set of mini-grammars for different domains so that, in effect, every speaker is bilingual. It is argued that Tense or Agreement Checking, V-2 for quotation, and resumptive pronouns, all lead to bilingual representations. In addition, this perspective on Theoretical Bilingualism suggests that optionality and stages in the acquisition of an initial grammar should also be characterized as a form of bilingualism.

Research on the effects of bi- and multi-lingualism on brain structure has so far yielded variable patterns. Although it cannot be disputed that learning and using additional languages restructures grey (cortical, subcortical and cerebellar) and white matter in the brain, both increases and reductions in regional volume and diffusivity have been reported. This paper revisits the available evidence from simultaneous and sequential bilinguals, multilinguals, interpreters, bimodal bilinguals, children, patients and healthy older adults from the perspective of experience-based neuroplasticity. The Dynamic Restructuring Model (DRM) is then presented: a three-stage model accounting for, and reinterpreting, all the available evidence by proposing a time-course for the reported structural adaptations, and by suggesting that these adaptations are dynamic and depend on the quantity and quality of the language learning and switching experience. This is followed by suggestions for future directions for the emerging field of bilingualism-induced neuroplasticity.

The lack of consistency in how bilingual language dominance is assessed currently impedes cross-experiment comparisons (Grosjean, 1998). We present a paper-and-pencil dominance scale that can be used to quantify the language dominancy of bilingual participants. The scale targets three main criteria important in gauging dominance (Grosjean, 1998; Flege, Mackay & Piske, 2002): percent of language use for both languages, age of acquisition and age of comfort for both languages, and restructuring of language fluency due to changes in linguistic environments. Reaction times from a Spanish/English lexical translation task and filler rates and elongation rates from a Spanish/English sentence translation task support the validity of the scale. The scale can be adapted for nonliterate populations by asking questions verbally and recording responses.

How does age of first bilingual language exposure affect reading development in children learning to read in both of their languages? Is there a reading advantage for monolingual English children who are educated in bilingual schools? We studied children (grades 2–3, ages 7–9) in bilingual Spanish–English schools who were either from Spanish-speaking homes (new to English) or English-speaking homes (new to Spanish), as compared with English-speaking children in monolingual English schools. An early age of first bilingual language exposure had a positive effect on reading, phonological awareness, and language competence in both languages: early bilinguals (age of first exposure 0–3 years) outperformed other bilingual groups (age of first exposure 3–6 years). Remarkably, schooling in two languages afforded children from monolingual English homes an advantage in phoneme awareness skills. Early bilingual exposure is best for dual language reading development, and it may afford such a powerful positive impact on reading and language development that it may possibly ameliorate the negative effect of low SES on literacy. Further, age of first bilingual exposure provides a new tool for evaluating whether a young bilingual has a reading problem versus whether he or she is a typically-developing dual-language learner.

A growing body of research has investigated bilingual sentence processing. How to account for differences in native (L1) and non-native (L2) processing is controversial. Some explain L1/L2 differences in terms of different parsing mechanisms, and the hypothesis that L2 learners adopt ‘shallow’ parsing has received considerable attention. Others assume L1/L2 processing is similar, and explain L1/L2 differences in terms of capacity-based limitations being exceeded during L2 processing. More generally, the role that working memory plays in language acquisition and processing has garnered increasing interest. Based on research investigating L2 sentence processing, I claim that a primary source of L1/L2 differences lies in the ability to retrieve information constructed during sentence processing from memory. In contrast to describing L1/L2 differences in terms of shallow parsing or capacity limitations, I argue that L2 speakers are more susceptible to retrieval interference when successful comprehension requires access to information from memory.

In this study we examined ERP (event-related-potential) responses in the morphosyntactic processing of subject–verb agreements by L2 Chinese learners of English. Fifteen proficient L2 learners and fifteen native English speakers were presented with English sentences that varied in the grammaticality of the sentence with respect to subject–verb agreement. Our results indicate that late L2 learners show distinct ERP responses from native speakers in the processing of syntactic features that are absent in their L1, even when their behavioral patterns are similar to those of native speakers. The results are taken to support the proposal that language-specific experiences with L1 shape the neural structure of processing in L2.

Models of bilingual speech production generally assume that translation equivalent lexical nodes share a common semantic representation. Though this type of architecture is highly desirable on both theoretical and empirical grounds, it could create difficulty at the point of lexical selection. If two translation equivalent lexical nodes are activated to roughly equal levels every time that their shared semantic representation becomes activated, the lexical selection mechanism should find it difficult to “decide” between the two (the “hard problem”) – yet in some cases bilinguals benefit from the presence of a translation equivalent “competitor”. In this article, we review three models that have been proposed as solutions to the hard problem. Each of these models has difficulty accounting for the full range of findings in the literature but we suggest that these shortcomings stem from their acceptance of the assumption that lexical selection is competitive. We argue that without this assumption each proposal is able to provide a full account of the empirical findings. We conclude by suggesting that the simplest of these proposals should be rejected before more complicated models are considered.

Is parental language mixing related to vocabulary acquisition in bilingual infants and children? Bilingual parents (who spoke English and another language; n = 181) completed the Language Mixing Scale questionnaire, a new self-report measure that assesses how frequently parents use words from two different languages in the same sentence, such as borrowing words from another language or code switching between two languages in the same sentence. Concurrently, English vocabulary size was measured in the bilingual children of these parents. Most parents reported regular language mixing in interactions with their child. Increased rates of parental language mixing were associated with significantly smaller comprehension vocabularies in 1.5-year-old bilingual infants, and marginally smaller production vocabularies in 2-year-old bilingual children. Exposure to language mixing might obscure cues that facilitate young bilingual children's separation of their languages and could hinder the functioning of learning mechanisms that support the early growth of their vocabularies.

The point of departure of this study is the well-known hypothesis according to which structures that involve the syntax–pragmatics interface and instantiate a surface overlap between two languages are more vulnerable to crosslinguistic influence than purely syntactic domains (e.g. Müller and Hulk, 2001). In exploring the validity of this hypothesis for later stages of bilingual acquisition, the study aims to establish whether crosslinguistic influence occu only in one direction, i.e. from English to Greek, which structural factors can account for the directionality of crosslinguistic effects, and whether language dominance plays a role in determining the occurrence and the strength of these effects in older bilingual children. Experimental data are presented from 32 English–Greek eight-year-old simultaneous bilinguals – 16 Greek-dominant living in Greece and 16 English-dominant living in the UK – and monolingual control groups. A number of syntax–pragmatics interface and narrow syntax structures were investigated and the results showed that both types of structures were found to be selectively vulnerable to crosslinguistic influence in the predicted direction, but only in the grammar of the English-dominant bilinguals.

Here we report findings from a cross-sectional study of morphosyntactic processing in native German speakers and native English speakers enrolled in college-level German courses. Event-related brain potentials were recorded while participants read sentences that were either well-formed or violated German subject–verb agreement. Results showed that grammatical violations elicited large P600 effects in the native Germans and learners enrolled in third-year courses. Grand mean waveforms for learners enrolled in first-year courses showed a biphasic N400–P600 response. However, subsequent correlation analyses revealed that most individuals showed either an N400 or a P600, but not both, and that brain response type was associated with behavioral measures of grammatical sensitivity. These results support models of second language acquisition which implicate qualitative changes in the neural substrates of second language grammar processing associated with learning. Importantly, we show that new insights into L2 learning result when the cross-subject variability is treated as a source of evidence rather than a source of noise.

The current study investigated the effects of bilingualism on the clinical manifestation of Alzheimer's disease (AD) in a European sample of patients. We assessed all incoming AD patients in two university hospitals within a specified timeframe. Sixty-nine monolinguals and 65 bilinguals diagnosed with probable AD were compared for time of clinical AD manifestation and diagnosis. The influence of other potentially interacting variables was also examined. Results indicated a significant delay for bilinguals of 4.6 years in manifestation and 4.8 years in diagnosis. Our study therefore strengthens the claim that bilingualism contributes to cognitive reserve and postpones the symptoms of dementia.

Tip-of-the-tongue states (TOTs) in proficient Hebrew–English bilinguals were compared to those of age-matched monolinguals. Monolinguals retrieved words in English, and bilinguals retrieved words from both languages. Results showed an increased TOT rate in bilinguals. However, bilinguals demonstrated comparable rates of spontaneous resolution, and similar ability to access partial information about target words. Interestingly, bilinguals named the same number of targets as monolinguals when naming an item in either language was counted as a correct response. Besides bilingualism, other factors that predicted TOT rate included word frequency (only for bilinguals), and age (younger participants had more TOTs). Unexpectedly, TOTs for Hebrew targets were not characterized by increased access to grammatical gender and number of syllables relative to control states, thus contrasting notably with TOTs for Italian and English targets respectively. We discuss these results in terms of their relevance for constraining models of bilingual lexical access and models of TOT.

Cross-language priming effects using masked primes tend to be asymmetrical. Priming from L1 to L2 is strong, but priming from L2 to L1 is inconsistent and weak. Two kinds of explanations may explain this asymmetry. The representation hypothesis attributes the asymmetry to the different strength of connections between lexical items in the two languages. The processing hypothesis explains the asymmetry by emphasizing differences in processing speed or the general activation level of the two languages. In this study, three versions of the processing hypothesis were examined. Chinese–English bilinguals were tested with a masked priming paradigm on Chinese–English translation pairs in five experiments. Experiments 1 and 2 replicated the asymmetrical pattern of cross-language priming. Experiments 3 to 5 examined three processing-related hypotheses by varying prime and target presentation conditions. The results showed that none of the three processing accounts provides a satisfactory explanation for the asymmetry. The findings are discussed in the context of current models of bilingual memory organization.

In this study we examined the level of English proficiency children can obtain through out-of-school exposure in informal contexts prior to English classroom instruction. The second aim was to determine the input types that fuel children's informal language acquisition. Language learning was investigated in 780 Dutch-speaking children (aged 10–12), who were tested on their English receptive vocabulary knowledge, listening, speaking, reading and writing skills. Information about learner characteristics and out-of-school English exposure was gathered using questionnaires. The results show large language gains for a substantial number of children but also considerable individual differences. The most beneficial types of input were gaming, use of social media and speaking. These input types are interactive and multimodal and they involve language production. We also found that the various language tests largely measure the same proficiency component.

This paper provides a case study of the fossilized endstate L2 English grammar of an adult native speaker of Turkish. Results are presented from production data (over 3400 utterances, gathered over 2 time periods 18 months apart), concentrating on verbal and nominal inflection and associated syntactic properties; data from a number of other tasks are also presented. A high level of accuracy in suppliance of English tense and agreement morphology was found. In contrast, suppliance of definite and indefinite articles was significantly lower but nevertheless appropriate. Syntactic correlates (such as verb placement, presence of overt subjects, case assignment, definiteness effects) were all completely accurate, suggesting no underlying impairment to functional categories or features. There is some evidence for influence from the L1, which has rich inflection but lacks articles, but this appears to be an effect on suppliance of overt morphology and not on underlying representation, which shows properties appropriate to the L2.

The present study investigates the link between multilingualism and the personality trait Tolerance of Ambiguity (TA) among 2158 mono-, bi- and multilinguals. Monolinguals and bilinguals scored significantly lower on TA compared to multilinguals. A high level of global proficiency of various languages was linked to higher TA scores. A stay abroad of more than three months was also linked to higher TA although the effect levelled off after one year. Growing up in a multilingual family had no effect on TA. These findings show that a high level of multilingualism makes individuals more at ease in dealing with ambiguity, but we acknowledge that a higher level of TA can also strengthen an individual's inclination to become multilingual.

English receptive vocabulary scores from 797 monolingual and 808 bilingual participants between the ages of 17 and 89 years old were aggregated from 20 studies to compare standard scores across language groups. The distribution of scores was unimodal for both groups but the mean score was significantly different, with monolinguals obtaining higher standard scores than bilinguals. Consistent with previous research, older adults had higher vocabulary scores than younger adults. The results are discussed in terms of the implications for theoretical conceptions of linguistic processing and clinical diagnosis in bilingual populations.

Two studies investigated five- and six-year-old preschool children's narrative production in an attempt to show how LI may impinge on narrative production in measurable ways. Study 1 analyzed renderings of familiar stories for group (typical language development vs. language impairment), story content (Jungle Book/Goldilocks) and language (English/Hebrew) differences on a range of discourse (story grammar categories), lexical (e.g., words, word types), morphosyntactic (e.g., verb inflections, prepositions) and bilingual (code-switching) measures. It showed intact performance for narrative structure in both groups and in both languages despite differences in lexis, morphosyntax and bilingualism. Study 2 pursued bilingual code-switching as a means to examine differences between children with typical language development (TLD) and language impairment (LI) in a retelling task where each child retold three stories (from native language/L1, second language/L2 and bilingual contexts) to interlocutors with different language preferences. Both groups showed sociolinguistic sensitivity in code-switching behavior, but frequency and directionality of code-switching revealed group differences. The article argues for the use of a range of indicators of LI including those unique to bilingual children.

The present study investigates voice onset times (VOTs) to determine if cognates enhance the cross-language phonetic influences in the speech production of a range of Spanish–English bilinguals: Spanish heritage speakers, English heritage speakers, advanced L2 Spanish learners, and advanced L2 English learners. To answer this question, lexical items with considerable phonological, semantic, and orthographic overlap (cognates) and lexical items with no phonological overlap with their English translation equivalents (non-cognates) were examined. The results indicate that there is a significant effect of cognate status in the Spanish production of VOT by Spanish–English bilinguals. These bilinguals produced /t/ with longer VOT values (more English-like) in the Spanish production of cognates compared to non-cognate words. It is proposed that the exemplar model of lexical representation (Bybee, 2001; Pierrehumbert, 2001) can be extended to include bilingual lexical connections by which cognates facilitate phonetic interference in the bilingual mental lexicon.

This study investigates ultimate attainment at the syntax–discourse interface in adult second-language (L2) acquisition. In total, 91 L1 (first-language) English, L1 Dutch and L1 Russian advanced-to-near-native speakers of German and 63 native controls are tested on an acceptability judgement task and an on-line self-paced reading task. These centre on discourse-related word order optionality in German. Results indicate that convergence at the syntax–discourse interface is in principle possible in adult L2 acquisition, both in off-line knowledge and on-line processing, even for L1 English speakers, whose L1 does not correspond to L2 German in discourse-to-syntax mappings. At the same time, non-convergence of the L1 Dutch groups and differences in the L2 groups' performance between tasks suggest that asymmetries in L1–L2 discourse configurations and computational difficulties in mapping discourse onto syntax constrain L2 performance.