Efficient comprehension of sentences requires rapidly and continuously accessing and integrating different sources of information in real time. Psycholinguists have developed detailed models and theories to account for the processes involved in on-line sentence comprehension as well as a number of sophisticated experimental designs for studying these processes. But how about real-time sentence processing in bilinguals? The study of bilingual sentence processing has received considerable attention and has led to a remarkable growth of experimental studies over the last 10 years. The focus of these studies has been on late bilinguals, i.e., on second-language (L2) learners who learned a non-native language after early childhood, as adolescents or adults. These studies have revealed both similarities and differences between native (L1) and non-native (L2) sentence processing. Several proposals have been made to account for the experimental findings, but the significance and nature of native vs. non-native differences in sentence processing has remained controversial. Some researchers have claimed that L1 and L2 sentence processing are essentially the same and that observed performance differences between native and non-native sentence comprehension are due to peripheral factors, e.g., decoding problems, working memory limitations, slower processing speed, difficulties with lexical access and retrieval, or a reduced ability to predict during L2 processing (e.g., McDonald, 2006; Hopp, 2016; Kaan, 2014). Others have posited more substantial differences between L1 and L2 processing. One prominent proposal is Clahsen and Felser's (2006a, b) Shallow-Structure Hypothesis (SSH). Assuming multi-stream models of language processing (e.g., Ferreira & Patson, 2007) with two routes from form to meaning, a heuristic one that employs surface-form information, lexical and semantic cues, and an algorithmic route that relies on a full grammatical parse, the SSH holds that L2 processing relies less on grammatical and more on non-grammatical information sources, in comparison to L1 processing of syntactic (and morphological) phenomena.

The question of how much language a child can learn by modelling the patterns she is exposed to in the environment represents an age-old and persistent controversy in language-acquisition research. On a number of occasions researchers felt confident enough to claim that the controversy had been resolved, in favour of their own viewpoint, of course. One such attempt was Skinner's (1957) behaviourist view of language development, which gave a prominent if not exclusive role to input and experience. After Chomsky's (1959) landmark review, however, Skinner's account was left in pieces and was not further pursued by many. A more recent attempt comes from usage-based accounts according to which children directly build linguistic categories and rules from the language they hear around them. Some believe that these accounts have resolved the controversy for good and have ‘overturned’ alternative less experience-driven approaches (e.g., Ibbotson & Tomasello, 2016; Dabrowska, 2015). Yet, casual inspection of recent research articles reveals that this announcement may be somewhat premature; see, for example, Everaert, Huybregts, Chomsky, Berwick and Bolhuis (2015), Boxell's (2016) rebuttal of Dabrowska (2015), and many acquisition studies published in the journal Language Acquisition.

This special issue deals with cross-linguistic priming in bilinguals, and consists of six contributions, which were all presented during the workshop on cross-linguistic priming in bilinguals at Radboud University Nijmegen (NL) in September 2013 (http://crosslingprimingconf2013.wordpress.com).

How do late proficient bilinguals process morphosyntactic and lexical-semantic information in their non-native language (L2)? How is this information represented in the L2 mental lexicon? And what are the neural signatures of L2 morphosyntactic and lexical-semantic processing? We addressed these questions in one behavioral and two ERP priming experiments on inflected German adjectives testing a group of advanced late Russian learners of German in comparison to native speaker (L1) controls. While in the behavioral experiment, the L2 learners performed native-like, the ERP data revealed clear L1/L2 differences with respect to the temporal dynamics of grammatical processing. Specifically, our results show that L2 morphosyntactic processing yielded temporally and spatially extended brain responses relative to L1 processing, indicating that grammatical processing of inflected words in an L2 is more demanding and less automatic than in the L1. However, this group of advanced L2 learners showed native-like lexical-semantic processing.

Bilinguals show word use patterns in each of their languages that differ from those of monolinguals. One interpretation is that, for bilinguals, the word meanings of one language are influenced by those of the other. Another is that the cross-language influence lies in on-line processes – word retrieval probabilities or word form activation levels. To discriminate between interpretations, we asked Mandarin–English bilinguals to name household objects in their L1 and L2 via forced choice instead of free production. The options given were the monolingual-preferred choices, eliminating memory retrieval demands and keeping those words at a high level of activation. For comparison, monolinguals of each language performed the same task in their native language. Differences from monolinguals in word choice were substantially reduced, especially in L1, but bilingual patterns still showed some cross-language influence in both L1 and L2. This outcome implicates cross-language influences on both bilingual processing and meaning representations.

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.

A growing literature on bilingual development explores relationships between language exposure and learning outcomes. Vocabulary size and pace of grammar learning have been claimed to be causally related to amounts or types of exposure to each language. Strong claims are made about the role of exposure on bilingual outcomes. Some researchers posit a unique learning result: a ‘weak language’. In a critical review, I voice reasons for scepticism that quantity or quality of exposure alone will explain findings. Central constructs are not well defined; inappropriate research methods have been used; the right kind of data is not discussed. Crucially, authors prevaricate on the notion of language itself, switching between cognitive and environmental perspectives. Both are needed to interpret bilingual behaviours but play different roles in the construction of learner grammars.

This study uses a discontinuous-linear regression methodological approach to test the Linguistic Threshold Hypothesis (LTH). Specifically, we investigate the following hypotheses: (1) the rate of transfer of literacy skills from L1 to L2 is a function of L2 oral language ability, (2) the rate of transfer from L1 to L2 accelerates when students cross a specified threshold(s) of L2 language oral ability, and (3) discontinuous change-point regression models fit the data better than linear regression interaction models. Across literacy skills, discontinuous change-point regression models revealed levels of L2 oral language at which transfer from L1 to L2 literacy was maximized, suggesting that the relationship between L2 language and cross-linguistic transfer is not constant for the young Spanish–English bilinguals in our study. Further, discontinuous change-point regression models fit the data better than linear interaction models, suggesting the importance of using models that better match the theoretical assumptions underpinning the LTH.

In the current study, we examined how adult heritage and monolingual speakers of Turkish process evidentiality (the linguistic expression of information source) through finite verb inflections and time reference, expressed on non-finite participles. A sentence-verification task was used to measure participants’ sensitivity to evidentiality and time-reference violations in Turkish. Our findings showed that the heritage speakers were less accurate and slower than the monolinguals in responding to both evidentiality and time-reference violations. Also, the heritage speakers made more errors and had longer RTs when responding to evidentiality violations as compared to time-reference violations. The monolinguals had longer RTs (and more accurate responses) to time reference than to evidentiality violations. This study shows that evidentiality is susceptible to incomplete acquisition in Turkish heritage speakers. It is suggested that the requirement for simultaneous processing at different linguistic levels makes the evidentiality markers vulnerable.

According to Hartsuiker et al.'s (2004) shared-syntax account bilinguals share syntactic representations across languages whenever these representations are similar enough. But how does such a system develop in the course of second language (L2) learning? We will review recent work on cross-linguistic structural priming, which considered priming in early second language learners and late second language learners as a function of proficiency. We will then sketch our account of L2 syntactic acquisition. We assume an early phase in which the learner relies on transfer from L1 and imitation, followed by phases in which language- and item-specific syntactic representations are added and in which such representations become increasingly abstract. We argue that structural priming effects in L2 (and between L1 and L2) depend on the structure of this developing network but also on explicit memory processes. We speculate that these memory processes might aid the formation of new representations.

In his article, Parsing and working memory in bilingual sentence processing, Cunnings invites us to consider the hypothesis that important differences in how L1 and L2 populations process sentences stem from differences in how these speakers store and retrieve linguistic encodings in memory during the course of sentence comprehension (Cunnings, 2016). Specifically, he proposes that L2 speakers are more susceptible to similarity-based retrieval interference than their L1 counterparts, and L2 speakers weight discourse cues more heavily than syntactic cues when resolving open linguistic dependencies via memory retrieval. I find these to be interesting hypotheses that merit further investigation, especially in light of the prominence that these issues currently enjoy in L1 processing research. Nonetheless, I sound a note of caution: these claims go quite a bit beyond what is currently known, either theoretically or empirically. This makes support for these claims weak at present, but happily, this state of affairs offers clear directions for future research.

Structural priming is the phenomenon that speakers tend to re-use structures they have recently comprehended or produced themselves. Most studies on this topic are experimental and looked at within-language priming. However, there are now also many observational studies, a development that is inextricably related to new/larger corpora, new statistical methodologies, and new theoretical ideas. Second, there is a growing body of research on cross-linguistic structural priming, though mostly experimental. These developments lead to a new potential research avenue: cross-linguistic priming on the basis of observational data. Here, we will first summarize some fundamental studies of cross-linguistic priming, and then trace the historical development of observational studies of structural priming to showcase how statistical and theoretical developments have shaped research on priming in general and discuss what such observational priming research has offered to within-language priming research. We end with a discussion of how this research can inform cross-linguistic priming.

We investigated how two groups of Turkish–Dutch bilinguals and two groups of monolingual speakers of the two languages described static topological relations. The bilingual groups differed with respect to their first (L1) and second (L2) language proficiencies and a number of sociolinguistic factors. Using an elicitation tool that covers a wide range of topological relations, we first assessed the extensions of different spatial expressions (topological relation markers, TRMs) in the Turkish and Dutch spoken by monolingual speakers. We then assessed differences in the use of TRMs between the two bilingual groups and monolingual speakers.

In both bilingual groups, differences compared to monolingual speakers were mainly observed for Turkish. Dutch-dominant bilinguals showed enhanced congruence between translation-equivalent Turkish and Dutch TRMs. Turkish-dominant bilinguals extended the use of a topologically neutral locative marker.

Our results can be interpreted as showing different “bilingual optimization strategies” (Muysken, 2013) in bilingual speakers who live in the same environment but differ with respect to L2 onset, L2 proficiency, and perceived importance of the L1.

An account of code-switching should be a direct consequence of an understanding of representation and processing in the individual mind, rather than a separate domain of its own. In the absence of such an account, most studies have developed hypotheses strictly within a specific research domain. This paper seeks to apply to code-switching a reasonably well-developed account of the multilingual mind, the MOGUL framework, within which more specific accounts can be developed. After briefly summarizing the framework, we describe representation and processing as realized in MOGUL, focusing on aspects having particular relevance to code-switching, including social factors involved in switching but as seen in terms of their place in a cognitive system. We then show how a promising approach to code-switching can be derived from this general framework. Some specific examples of code-switching are analyzed, though the primary goal is to show the merits of a broader perspective.

The study of bilingual development has been, and must be, an interdisciplinary endeavor; Carroll (Carroll) presents us with a perspective from within one particular discipline, that of generative linguistics. From this vantage point, she provides us perhaps most importantly with the reminder that language is not a unitary construct, and cautions against extrapolating from findings on the learning of one particular aspect of language, such as vocabulary, to language acquisition more broadly. I wholeheartedly agree (for a similar point, see Paradis & Grüter, 2014). I do not agree, however, with Carroll's implication that such unwarranted extrapolation is characteristic of current research on input and bilingual development. A number of recent studies have looked specifically at the differential relation between input (in a wide sense) and bilingual children's acquisition of different linguistic phenomena. Unsworth (2014), for example, reported different effects of input variation on Dutch–English bilingual children's acquisition of grammatical gender versus indefinite object scrambling.

Memory is an integral part of language processing. Given this, a better understanding of how people learn, represent and process language requires considerations of the principles of memory that support language comprehension. Cunnings’ paper (Cunnings, 2016) does just this. The core of his proposal is that second language (L2) processing that is non-target like can be explained in terms of memory operations rather than by invoking a shallow processor (cf. Clahsen & Felser, 2006).

Monolingual listeners continuously predict upcoming information. Here, we tested whether predictive language processing occurs to the same extent when bilinguals listen to their native language vs. a non-native language. Additionally, we tested whether bilinguals use prediction to the same extent as monolinguals. Dutch–English bilinguals and English monolinguals listened to constraining and neutral sentences in Dutch (bilinguals only) and in English, and viewed target and distractor pictures on a display while their eye movements were measured. There was a bias of fixations towards the target object in the constraining condition, relative to the neutral condition, before information from the target word could affect fixations. This prediction effect occurred to the same extent in native processing by bilinguals and monolinguals, but also in non-native processing. This indicates that unbalanced, proficient bilinguals can quickly use semantic information during listening to predict upcoming referents to the same extent in both of their languages.

Sustained interaction between a bilingual's two languages can be a first step toward diachronic language change. We describe two investigations that explore this by examining how bilinguals process innovative syntactic structures in their first language. In the first investigation, a sentence recall/sentence matching task, bilinguals and monolinguals exhibited differences in their tolerance of expressions of induced motion, which vary in acceptability between the two languages (Portuguese and English). In the second investigation, a priming methodology was employed to induce bilinguals to produce in their first language (Spanish) innovative constructions modeled on the second language (English), using materials where the alternation is shared between the two languages (voice, reciprocal) or not (dative). The two investigations provide a window into how languages interact in bilinguals, inducing tolerance of ungrammaticality which, we will argue, could lead to long-term novel representations in the linguistic competence repositories.

We report the results from an eye-movement monitoring study that investigated late German–English bilinguals’ sensitivity to parasitic gaps inside subject islands. The online reading experiment was complemented by an offline scalar judgement task. The results from the offline task confirmed that for both native and non-native speakers, subject island environments must normally be non-finite in order to host a parasitic gap. The analysis of the reading-time data showed that, while native speakers posited parasitic gaps in non-finite environments only, the non-native group initially overgenerated parasitic gaps, showing delayed sensitivity to island-inducing cues during online processing. Taken together, our findings show that non-native comprehenders are sensitive to exceptions to island constraints that are not attested in their native language and also rare in the L2 input. They need more time than native comprehenders to compute the linguistic representations over which the relevant restrictions are defined, however.

Before bilingual children can say anything, they must learn to distinguish between the two languages that are spoken to them, and they must learn to make useful perceptual distinctions in each of them in order to understand what is said to them. Conversational interaction and non-verbal communication, such as pointing and gaze, aid children in attending to and processing aspects of their “language input environment” (De Houwer, 2009, 2011), “exposure” in Carroll's terms. As Carroll points out, children must build up their linguistic categories based on their intrinsically category-free “exposure”: they must process speech to acquire language. This reminds me of Wijnen's (2000) notion of language intake, which is the “data base children use to derive hypotheses on the structure of the target grammar” (p. 174), and which constitutes children's selection from what I will continue to call input, pace Carroll.