Interest in third language (L3) acquisition has increased exponentially in recent years, due to its potential to inform long-lasting debates in theoretical linguistics, language acquisition and psycholinguistics. From the very beginning, researchers investigating child and adult L3 acquisition have considered the many diverse cognitive factors that constrain and condition the initial state and development of newly acquired languages, and their models have duly evolved to incorporate insights from the most recent findings in psycholinguistics, neurolinguistics and cognitive psychology. The articles in this Special Issue of Bilingualism: Language and Cognition, in dealing with issues such as age of acquisition, attrition, relearning, cognitive economy or the reliance on different memory systems – to name but a few – provide an accurate portrayal of current inquiry in the field, and are a particularly fine example of how instrumental research in language acquisition and other cognitive domains can be to each other.

While research on third language (L3) and multilingualism has recently shown remarkable growth, the fundamental question of what makes trilingualism special compared to bilingualism, and indeed monolingualism, continues to be evaded. In this contribution we consider whether there is such a thing as a true monolingual, and if there is a difference between dialects, styles, registers and languages. While linguistic and psycholinguistic studies suggest differences in the processing of a third, compared to the first or second language, neurolinguistic research has shown that generally the same areas of the brain are activated during language use in proficient multilinguals. It is concluded that while from traditional linguistic and psycholinguistic perspectives there are grounds to differentiate monolingual, bilingual and multilingual processing, a more dynamic perspective on language processing in which development over time is the core issue, leads to a questioning of the notion of languages as separate entities in the brain.

The first part of this paper reviews research evidence for typological similarity and/or L2 status as determinants of cross-linguistic influence (CLI) in multilingual lexical production. The second part presents a model of vocabulary acquisition as a framework to explain CLI at the levels of form, (syntactic) frame, and meaning, as well as some of the developmental changes that have been reported for CLI patterns in relation to L3 learners’ proficiency. It is suggested that these patterns can be related to default processes and stages involved in the acquisition of individual word forms and their integration into networks of existing lexical triads, as described in the Parasitic Model of vocabulary acquisition. The third part of this paper points to research into the complexity and non-linearity of multilingual lexical development and the need to learn more about it.

Heritage speakers who re-learn their childhood language in adulthood are an important group for the study of L3 acquisition. Such re-learners have selective advantages over other L2/L3 learners in phonetics/phonology, but lack a global advantage at re-learning the prestige variety of their L1. These learners show asymmetrical transfer effects in morphosyntax: transfer occurs only from the dominant language. Two tentative explanations for this asymmetry are suggested. First, re-learners may deploy the skills acquired in a classroom setting, where they have used only their dominant language. Second, re-learners may implicitly strive to increase the typological distance between their childhood language and the language of classroom instruction. These findings have implications for models of L3/Ln learning: the Cumulative Enhancement Model, the Typological Proximity Model, and the L2 Status Factor Model. The data discussed in this paper are most consistent with the latter model, but they also highlight the significance of the typological distance between languages under acquisition.

This article elucidates the Typological Primacy Model (TPM; Rothman, 2010, 2011, 2013) for the initial stages of adult third language (L3) morphosyntactic transfer, addressing questions that stem from the model and its application. The TPM maintains that structural proximity between the L3 and the L1 and/or the L2 determines L3 transfer. In addition to demonstrating empirical support for the TPM, this article articulates a proposal for how the mind unconsciously determines typological (structural) proximity based on linguistic cues from the L3 input stream used by the parser early on to determine holistic transfer of one previous (the L1 or the L2) system. This articulated version of the TPM is motivated by argumentation appealing to cognitive and linguistic factors. Finally, in line with the general tenets of the TPM, I ponder if and why L3 transfer might obtain differently depending on the type of bilingual (e.g. early vs. late) and proficiency level of bilingualism involved in the L3 process.

This study examines three formal linguistic acquisition models of third language (L3) acquisition in the context of Brazilian Portuguese (BP), specifically examining Differential Object Marking (DOM). The main goal is to determine which of the models is best able to predict and explain syntactic transfer in three experimental groups: mirror-image groups of first/second language (L1/L2) English/Spanish bilinguals (i) L1 English/L2 Spanish and (ii) L1 Spanish/L2 English, and (iii) heritage Spanish/English bilinguals. The data provide evidence to support the Typological Primacy Model (Rothman, 2010, 2011, 2013), which predicts Spanish transfer irrespective of its status as an L1, L2 or bilingual first language (2L1). Additionally, the heritage speaker and L1 English group results, taken together, provide evidence for Iverson's (2009) claim that comparing such populations adds independent supportive evidence that the acquisition of linguistic features or properties in an L2 acquired past puberty is not subject to a maturational critical period.

This article considers the acquisition of three English syntax–discourse interface constructions: Topicalization, Focus Fronting and Left Dislocation. We use data from Basque–Spanish bilinguals learning English as a third language (L3) as a test case for the Interface Hypothesis (IH, Sorace, 2011). The IH has made specific predictions about second language (L2) acquisition and such predictions can be extrapolated to L3 on the basis of interface delay explanations. Thirty contexts and embedded test sentences with and without pronouns were used; participants had to rate the acceptability of each audio stimulus sentence in the context on a seven-point scale. We tested Basque–Spanish bilinguals dominant in Basque (n = 23), Basque–Spanish bilinguals dominant in Spanish (n = 24), Spanish L2 English learners (n = 39) as well as native English speakers (n = 24). Findings provide evidence against current L3 acquisition models and potential arguments for both cumulative enhancement as well as cumulative inhibition as possible processes in L3 acquisition.

In this study we explore the role of explicit metalinguistic knowledge (MLK) of first language (L1) in the learning of a third language (L3). We compare the oral production of 40 participants with varying degrees of explicit MLK of the L1, who are exposed to a completely new L3. In accordance with the second language (L2) status factor, which is further motivated by the distinction between implicit competence and explicit knowledge (Bardel & Falk, 2012; Paradis, 2009), we hypothesize that the participants with low explicit MLK in their L1 will transfer from their L2, and that the participants with high explicit MLK in the L1 will transfer from their L1. The structure of interest is adjective placement, which is the same in the L1 and the L3 (but not in the participants’ L2s). The results show that the degree of explicit MLK in the L1 plays a decisive role at the initial state of L3 learning.

The present study follows the role of the first (L1, English) and second (L2, Japanese or Spanish) languages in ab initio third language (L3, Latin) acquisition. Participants (N = 25) were L2 classroom learners without immersion experience. In order to complement previous generativist studies and to offer a fuller developmental account of how transfer operates at the morphosyntactic level, the Competition Model (CM) was adopted as theoretical framework. Positive changes in overall accuracy and sentence processing patterns in role assignment in L3 Latin show L3 development as largely modulated by the L1, suggesting that higher levels of L2 resonance are necessary for integrated patterns of L1 and L2 cues to emerge.

This paper reports the findings of a four-year longitudinal study that examined the role of prior linguistic knowledge on the written L3 production of 93 Spanish/Catalan learners. Two research questions guided the study: the first asked whether a background language (L1s Spanish/Catalan, L2 German) would activate in parallel with L3 English during word construction attempts involving verbal forms, and if so, which would be the source language of blending. The second addressed the progressive readjustments of L2 activation and blending in the course of the first 200 hours of instruction. The elicitation technique was a written narrative based on a story telling task. Data were collected first when the learners were on average 9.9 years old (T1), and again at the ages of 10.9 (T2), 11.9 (T3) and 12.9 (T4). The focus of analysis was on word construction attempts that involved verbal forms. The results suggest that a background language, the L2, did indeed activate, especially at early stages of L3 acquisition.

This study examined behavioral and neurophysiological indices of discrimination of an English vowel contrast [ɪ–ɛ] by early and late bilingual Spanish–English speakers, compared to monolingual English speakers. Electrophysiological measures (Mismatched Negativity – MMN) and behavioral measures (AX discrimination and forced-choice identification) were employed to examine perception of a nine-step vowel continuum, re-synthesized from natural tokens. Results revealed that (i) both monolingual and early bilinguals showed similar behavioral perception while late bilinguals performed more poorly on all behavioral tasks; and (ii) monolinguals showed robust evidence of discrimination (MMN) at a pre-attentive level that was significantly larger than found for either early or late bilinguals. These findings suggested that early input of English vowels to bilinguals did not necessarily lead to robust, automatic processing, as measured at a more attention-independent neural level; but earlier experience with a second language allowed for native-like speech perception measured with behavioral tasks.

This study examined the production of the Dutch past tense in Dutch–Hebrew bilingual children and investigated the effect of type of past tense allomorph (de versus te) and token frequency on productions of the past tense. Seven-year-old bilingual children (n=11) were compared with monolingual children: age-matched (n=30) and younger vocabulary-matched (n=21). Accuracy of regular and novel past tense was similar for the bilingual and monolingual groups, but the former group was worse on irregular past tense than the age-matched monolingual peers. All three groups showed effects of type frequency: te past tenses were more accurate than de. The difference between the bilingual and monolingual children surfaces in the extent of the effect: for the bilingual children it was most pronounced in verbs with low token frequency and novel verbs. Results are interpreted as stemming from a learning strategy or from phonological transfer from the Hebrew morphosyntactic system.

This study analyzes gender assignment in Spanish–Basque mixed nominal constructions with nouns in Basque (a language that lacks gender) and determiners in Spanish (a language that marks gender) by using a multi-task approach: (i) naturalistic data, (ii) an elicitation task, and (iii) an auditory judgment task. Naturalistic data suggest cross-language effects under which a morphological marker of Basque (-a determiner) is interpreted as a morphophonological expression of gender marking in Spanish. A preference for feminine determiners was observed in the judgment task, which differs from the masculine default trend observed in Spanish–English bilinguals (Jake, Myers-Scotton & Gross, 2002). Our results point to feminine gender as default in Spanish–Basque mixed DPs, indicating that the resources that bilinguals use for gender assignment can be different from those of monolinguals. We argue that this is an outcome of interacting processes which take place at the interfaces (lexicon, phonology, morphosyntax) of both languages, resulting in cross-language effects.

The role of age of acquisition (AoA) in reaching native-like proficiency in second language is controversial. The existence of a critical period and the effect of AoA have been questioned by studies testing lexical and/or morphosyntactic skills, and by functional brain exploration. The aim of this study was to verify the effect of AoA and language practice on proficiency in a bilingual pragmatic task and its relationship with cognitive skills. The study involved a group of Italian–Spanish bilinguals, classified according to their AoA and language use. All participants performed a pragmatic bilingual test and a battery of cognitive tests. A multivariate analysis showed significant effects of language use and cognitive skills and a non-significant effect of AoA. These results indicate that continued language practice is a major factor influencing high bilingual proficiency, irrespective of AoA, suggesting that proficiency may be weakened when bilingual experience becomes occasional or ceases.

Some studies have shown that bilinguals gesture more than monolinguals. One possible reason for the high gesture frequency is that bilinguals rely on gestures even more than monolinguals in constructing their message. To test this, we asked French–English bilingual adults and English monolingual adults to tell a story twice; on one occasion they could move their hands and on the other they could not. If gestures aid bilinguals in information packaging and/or lexical access, bilinguals should tell shorter stories with fewer word types than monolinguals when their gestures are restricted. In fact, we found that gesture restriction affected bilinguals’ stories only in French, the language in which they used more gestures. These findings challenge the interpretation that bilinguals gesture frequently as an aid in constructing their message. We argue that cultural norms in gesture frequency interact with gesture use in message construction.

The Stroop task has become a popular paradigm in investigations of bilingual cognitive control. While several studies show a cognitive control advantage for bilinguals, recent studies have countered these findings. The present study investigates two factors that may account for conflicting results: participant grouping and task difficulty. While we find no differences between simultaneous and early bilinguals (age groups traditionally both classified as “early” bilinguals) when the task uses only one language, we find a significant difference between the two when languages are mixed. We suggest treating the two groups as distinct, and note the importance of the bilingual context.