Insights From Functional Neuroimaging Of L2 Syntax In The Brain

While syntactic theory is generally concerned with creating models to explain the syntactic phenomena observed in language use, this indirect explanation of syntactic structure and rules is only part of the explanation. Insight from other sources, especially the mind and brain, should also be considered part of syntactic inquiry. By using modern functional neuroimaging methods, researchers can get another perspective and shed some light on what happens in the brain when a speaker-listener is ‘doing syntax.’ This insight may be valuable in providing evidence for or against and helping to refine theories of syntax.

Another perspective that steps outside the most immediate usage of syntax or the most common subject on which syntactic theory is based is L2 syntax. By comparing native speakers’ syntactic patterns and processing to that of language learners, the similarities and differences may reveal insight about the underpinnings of the syntactic systems that govern speech.

In this paper, XXX functional neuroimaging studies on L2 syntax in the mind and brain are briefly summarized and evaluated. Finally, overall insights from this collection of studies on L2 syntax are discussed.

Bowden, H. W., Steinhauer, K., Sanz, C., & Ullman, M. T. (2013). Native-like brain processing of syntax can be attained by university foreign language learners. Neuropsychologia, 51(13), 2492-2511.

Bowden et al.’s study utilized EEG to measure language-related ERPs during semantic and syntactic processing of sentences with lexical and word-order violations in low-intermediate and mid-advanced L1 English/ L2 Spanish learners who studied Spanish at university as compared to the processing patterns of L1 Spanish speakers for the same stimuli. It is important to note that the more advanced L2 learners had also participated in study abroad while the lower proficiency learners had not. Results showed that the more advanced L2 learners had similar ERP patterning as the L1 speakers for both semantic and syntactic processing, while the lower proficiency learners only had similar patterning for semantic violations.

Bowden et al took this to demonstrate that the mechanisms of L2 language processing for semantics are similar to those of the L1, and that processing mechanisms for syntax start out similarly to the mechanisms of the L1, but grow more target-like over time. They also argue that their results indicate that the pedagogical format of university language courses (along with study abroad) is a sufficient learning environment to bring students to native-like processing ability. However, an issue with the study relates to the fact that the researchers did not also test advanced L2 Spanish learners who had not participated in study abroad, so it is not possible to ascertain how much of these participants’ syntactic processing proficiency is related to college language courses, and how much they gained from immersion in the L2 environment.

Golestani, N., Alario, F.-X., Meriaux, S., Le Bihan, D., Dehaene, S., & Pallier, C. (2006). Syntax production in bilinguals. Neuropsychologia, 44(7), 1029-1040.

Golestani et al. performed fMRI studies on “moderately fluent” (p.1030) bilingual speakers of L1 French/L2 English, measuring the neural activations of syntactic processing during silent reading and guided sentence production in both L1 and L2 to compare between languages and proficiency level of speakers. Results indicated activation in the brain areas commonly associated with the respective tasks, while differences in activation were also seen between L1 and L2 in the production task, with more activation in structures linked to rule-based systems during L1 production, and that L1 and L2 activations looked more similar in higher proficiency participants.

The authors attributed this finding to a greater reliance on native-like processing mechanisms as proficiency increases, or a potential effect of beginning L2 acquisition after a sensitive period for language learning. Drawbacks of this experimental method include the fact that activations seen during the tasks may not completely be attributable to syntactic processing alone; in other words syntactic processing is not completely separable from other language related processes that may appear in the fMRI scans, a point which the authors bring up. Furthermore, because the authors provided the participants with sentence frames from which to produce sentences, the processing mechanisms may be different from those used to form sentences spontaneously. A future study could focus on spontaneous production of sentences and attempt to ascertain whether significant differences in activation patterns are observed as task-based effects.

Guo, J., Guo, T., Yan, Y., Jiang, N., & Peng, D. (2009). ERP evidence for different strategies employed by native speakers and L2 learners in sentence processing. Journal of Neurolinguistics, 22(2), 123-134.

Using EEG, Guo et al. compared the ERP responses of “relatively proficient” (p.127) L1 Chinese/L2 English speakers and native English speakers when presented with sentence stimuli, some of which contained verb-subcategorization errors, via a reading comprehension task in order to evaluate the respective strategies used by each group of participants, as reflected in the ERPs. It was suggested that L2 speakers may rely more on “lexical-sematic strategy” (p. 127) (evidenced by an N400 ERP) when syntax processing was not sufficient, whereas native speakers would be able to use syntactic strageties (evidenced by a P600 ERP). Results were reported to show this pattern, leading the researchers to conclude that L2 learners lack the syntactic processing ability available to native speakers, leading them to look to semantic processing in order to comprehend sentences.

This shows that the two participant groups use different strategies based upon their language proficiency status. However, several aspects of this study can be critiqued. First, participants were asked to self-rate their proficiency, which is not the most accurate way of determining language ability, and all participants were grouped together. Since other studies (including XXX) have shown a difference between early and late L2 learners, it might be prudent to separate groups by proficiency level in studies such as this. Furthermore, the reserachers reported both temporal and spatial differences from the norm for their ERP measurements, though they still classified what they saw as P600 and N400. However, it may be worthwhile to look at these data more closely to ascertain whether the differences are actually significant and should be interpreted in another way.

Kotz, S. A., Holcomb, P. J., & Osterhout, L. (2008). ERPs reveal comparable syntactic sentence processing in native and non-native readers of English. Acta psychologica, 128(3), 514-527.

Kotz, Holcomb, and Osterhout extended the use of ERP measurements from investigations of syntactic violations to those of syntactic ambiguity by testing early Spanish L1-English L2 learners on syntactic violations and temporary syntactic ambiguity via a reading task. Results showed P600 responses in both situations, though the elements of the P600 responses differed, which was taken to indicate that other factors may also play a role in the neural activation responses. Because the participants were early learners of English, the authors suggest that early learning leads to ERP patterning similar to that of native speakers. However, it seems that is is difficult to state with certainty whether it was the early learning or overall proficiency of the participants that led to this finding.

Meulman, N., Stowe, L. A., Sprenger, S. A., Bresser, M., & Schmid, M. S. (2014). An ERP study on L2 syntax processing: When do learners fail? Frontiers in psychology, 5, 1072.

In this study, native Romance language learners of Dutch were given sentence comprehension tasks while ERPs were measured with an EEG. Stimuli were either sentences that included grammatical gender agreement, which was deemed a complicated syntactic structure for L2 speakers to acquire (due partly to the opacity of the gender agreement rules in Dutch), or non-finite verb agreement, which was considered an easier structure to acquire. L2 learners’ ERPs were compared with those of native Dutch speakers. Results indicated that while native Dutch speakers show a ‘biphasic’ N400-P600 pattern when encountering non-finite verb agreement issues, they showed only a P600 in the face of gender agreement issues. L2 learners had a native-like pattern of smaller magnitude for non-finite verb agreement stimuli, but showed no ERPs for the gender agreement stimuli. This was taken to indicate that the gender system in Dutch is complex. While this experiment provided information about L1 and L2 languages that both have gender agreement (with the L2 system being more opaque), future work could look at the reverse situation, or compare languages that have grammatical gender agreement to those that don’t.

Morgan-Short, K., Deng, Z., Brill-Schuetz, K. A., Faretta-Stutenberg, M., Wong, P. C., & Wong, F. C. (2015). A view of the neural representation of second language syntax through artificial language learning under implicit contexts of exposure. Studies in Second Language Acquisition, 37(2), 383-419.

Morgan-Short et al. attempted to model the effects of implicit instruction on syntax learning in declarative and procedural learning systems in the brain using an artificial L2 language, Brocanto2, as a way to begin addressing the issue of the effects of implicit and explicit L2 learning contexts. Participants were accessed for both procedural and declarative learning ability and trained and practiced with Brocanto2 over several sessions. Partipicants were given two grammatical judgement tasks (at early and late stages) based on the artificial language while inside an MRI scanner, and brain-imaging results were compared to a control in order to isolate effects of syntactic processing.

Results indicated a split among participants, with some appearing to utilize L1/procedural brain processes for the L2, while others showed an increased activation of areas related to attention and control. The authors interpret this finding to show that there may be differences in the location and processing of L2s in the brain. One point worth considering is that the particpants in this study had had previous exposure to other, natural L2s before taking part in this experiment, which may have affected the results or may be a potential factor in the observation of different processing strategies related to the artificial L2 language. The effects of this issue could be identified performing the same study on monolingual individuals and comparing the results of both experiments.

Pliatsikas, C., Johnstone, T., & Marinis, T. (2017). An fMRI study on the processing of long-distance wh-movement in a second language. Glossa: a journal of general linguistics, 2(1).

Pliatsikas, Johnstone, and Marinis utilized fMRI to investigate the neural representations of the theoretical syntactic procedure of Wh-movement in the L2. The authors discuss the Shallow Structure Hypothesis, which posits that L2 learners structural representations of sentences fail to include some abstract details of syntactic structure present in the L1, including traces left behind in the process of Wh-movement.

Reichle, R. V., & Birdsong, D. (2014). Processing focus structure in L1 and L2 French: L2 proficiency effects on ERPs. Studies in Second Language Acquisition, 36(3), 535-564.

Scherer, L. C., Fonseca, R. P., Amiri, M., Adrover-Roig, D., Marcotte, K., Giroux, F., Ansaldo, A. I. (2012). Syntactic processing in bilinguals: an fNIRS study. Brain and language, 121(2), 144-151.

Scherer et al. utilized an emerging neuroimaging method, functional near-infrared spectroscopy (FNIRS) which measures oxygenation and deoxygenation of blood in the brain in response to stimuli. They tested high-proficiency Portugese L1/French L2 individuals for their responses to subject-verb agreement violations as measured by FNIRS in both languages. Findings confirmed trends demonstrated in previous studies, including the presence of more brain activation during L2 processing as compared to L1 processing, including the use of both hemispheres at times, and some areas of shared activation between L1 and L2. The authors conclude that findings compatible with those observed with other neuroimaging methods give credence to the use of FNIRS as a neuroimaging tool, though they do not make a particularly strong case for the advantages of using FNIRS over other neuroimaging methods. (XXX add more conclusions about syntax)

Tanner, D., Inoue, K., & Osterhout, L. (2014). Brain-based individual differences in online L2 grammatical comprehension. Bilingualism: Language and Cognition, 17(2), 277-293.

Van Hell, J. G., & Tokowicz, N. (2010). Event-related brain potentials and second language learning: Syntactic processing in late L2 learners at different L2 proficiency levels. Second Language Research, 26(1), 43-74.

Wartenburger, I., Heekeren, H. R., Abutalebi, J., Cappa, S. F., Villringer, A., & Perani, D. (2003). Early setting of grammatical processing in the bilingual brain. Neuron, 37(1), 159-170.

Conclusion

While some studies’ results indicated native-like attainment in L2 syntax processing, some difficult concepts, such as gender agreement, seemed to cause issues for L2 learners. This indicates that learners are perhaps not utilizing the same processing mechanisms as L1 speakers or not doing so successfully. This insight valuable information that should be incorporated into a unified or overarching theory of syntax—how can theories account for both L1 and L2 syntax? Is it the same system or separate? These are questions that should be kept in mind as the field progresses.