Brain and Language Lab

Second Language and Bilingualism

This broad topic is one of our major areas of investigation. We are examining a number of issues and questions in this area.

First, in our theoretical work, we have proposed and are further developing the hypothesis that the learning, knowledge and use of second and additional languages depend on declarative and procedural memory (see especially Ullman, 2001, 2005, 2013, 2015, 2020). On this view - the declarative/procedural (DP) model of second language (L2) - later language learning should depend on the two memory systems, just as first language does. However, given that the memory systems change over the course of childhood, later learned languages should be learned somewhat differently than native languages. In particular, evidence suggests that learning and consolidation in declarative memory improves during childhood (and plateaus during adolescence and early adulthood), whereas learning and consolidation in procedural memory may be well-established early in childhood, and then might attenuate (though the evidence is less clear for developmental changes in procedural memory than in declarative memory). For these and other reasons (e.g., pedagogical instruction of later languages that might encourage explicit learning in declarative memory), later learned languages should depend more on declarative memory than native languages. However, this increased dependence on declarative memory should hold only for rule-governed aspects of grammar, which can depend on either memory system. In contrast, most lexical (idiosyncratic) knowledge can apparently be learned only in declarative memory, and thus should depend on this system in all language learners. Moreover, procedural memory is not posited to be defunct in adults, but simply less available for learning than during childhood (as compared to declarative memory). Therefore, contrary to strong versions of the critical period hypothesis, we predict that rule-governed aspects of grammar will eventually be learned in procedural memory, and thus should become increasingly native-like (first language-like) in their neurocognition over time and with practice/exposure. Finally, various learner, input, and item level factors should affect the extent to which grammar depends more or less on each of the two memory systems, and how this changes over time. For example, learners with a relative advantage in declarative memory (e.g., due to factors such as sex or genotype) should depend earlier and more on this system for grammar. Along the same lines, learning conditions (e.g., types of language training) that enhance learning in either declarative memory or procedural memory should lead to different patterns of dependence of grammar on the two memory systems (Ullman & Lovelett, 2018). Indeed, techniques that enhance learning in either system, such as spaced repetition, retrieval practice, exercise, or diet, should also enhance language learning in either system (Ullman & Lovelett, 2018). We found that Turkish learners of English show a striking benefit of combining spacing and testing, which yielded an 18 percentage-point increase from pretest to two post-tests (Karatas et al., 2021).

Second, we perform empirical studies to examine these predictions, as well as related issues. Our studies use a variety of techniques, including various behavioral methods (e.g., correlational approaches and the examination of frequency effects), event-related potentials (ERPs), and functional neuroimaging (fMRI). We investigate the learning, processing, representation, and retention of language, in various experimental linguistic paradigms, including with natural languages, mini-languages, artificial languages, and artificial grammars. Within natural languages we work mainly with English, but also examine other languages (e.g., Spanish). One exciting line of research has examined the neurocognitive effects (using behavioral and ERP measures) of instructed (explicit, classroom-like) versus uninstructed (implicit, immersion-like) training on the neurocognition of syntax, using an artificial language (Morgan-Short et al., JoCN, 2012). We found that only uninstructed/implicit training led to fully native-like patterns of brain processing. In a follow-up study we tested the learners 5 months later, and found that their brain patterns became more native-like for syntactic processing, and that this held for both the instructed/explicitly and uninstructed/implicitly trained groups, though again only the uninstructed group showed full native-like brain processing (Morgan-Short et al., PLoS ONE, 2012). We hypothesize that this increase in native-like brain processing over time was due to consolidation of syntactic knowledge, possibly in procedural memory. Another study found that university language learners of Spanish with classroom and immersion experience were able to attain native-like processing of syntax (Bowden et al., 2013). We have examined the effects of multiple factors, including sex (male vs. female), age of arrival, and length of residence on the computation (storage vs. composition) of inflected forms in L2 (Babcock et al., 2012). And in an fMRI study we investigated the learning and generalization of affixal morphology in an artificial language paradigm (Nevat et al., 2017).

We are also increasingly performing behavioral and neuroanatomical meta-analyses of second/additional language learning. In one recent paper, meta-analyses of correlational studies showed that grammatical processing abilities, across syntax and morphology, correlated with learning abilities in declarative memory (but not procedural memory) at early stages of L2 learning, whereas at later stages of L2 learning grammatical processing abilities correlated with learning abilities in procedural memory (but not declarative memory) (Hamrick et al., 2018). This paper convincingly links grammar to declarative memory at lower levels of L2 experience, but to procedural memory at higher levels, as predicted by the DP model. In another recent paper, we performed multiple neuroanatomical meta-analyses (using Activation Likelihood Estimation) to synthesize the functional neuroimaging literature of language learning. The analyses showed that grammar learning activates the anterior striatum (anterior caudate nucleus and anterior putamen), implicating procedural memory, while word learning activates occipito-temporal structures linked to the ventral stream and declarative memory. Moreover, grammar learning predicted to rely especially on declarative memory (e.g., with instructed explicit training) shows hippocampal involvement, while grammar learning predicted to rely particularly on procedural memory (e.g., with uninstructed implicit training) shows anterior striatal involvement (Tagarelli et al., 2019).

Finally, we investigate the neurocognitive effects of bilingualism. In an ERP study, Grey et al. (2018) found that bilinguals (who had learned both English and Mandarin at an early age) showed more native-like brain processing in learning an additional language than monolinguals (English-speaking).  And in a recent structural imaging study, we investigated the developmental patterns of both grey and white matter structures in a cross-sectional study of a large sample (n=711 for grey matter, n=637 for white matter) of bilingual and monolingual participants, aged 3-21 years. Metrics of grey matter (thickness, volume, surface area) and white matter (fractional anisotropy, mean diffusivity) were examined across 41 cortical and subcortical brain structures and 20 tracts, respectively.  As compared to monolinguals, bilinguals showed: a) more grey matter (less developmental loss) starting during late childhood and adolescence, mainly in frontal and parietal regions (particularly in the inferior frontal gyrus pars opercularis, superior frontal cortex, inferior and superior parietal cortex, and precuneus); and b) higher white matter integrity (greater developmental increase) starting during mid-late adolescence, specifically in striatal-inferior frontal fibers. The data suggest that there may be a developmental basis to the well-documented structural differences in the brain between bilingual and monolingual adults (Pliatsikas et al., 2020).


Hopp, H., Reifegerste, J., & Ullman, M.T. (in press, 2024). Lexical effects on L2 grammar acquisition: Testing psycholinguistic and neurocognitive predictions. Language Learning. 

Ullman, M. T., & Morgan-Short, K. (2023). How the declarative and procedural memory brain circuits support second language: Electrophysiological, neuroimaging, and neurological evidence. In The Routledge Handbook of Second Language Acquisition and Neurolinguistics (pp. 165-176). Routledge.

Morgan-Short, K., and Ullman, M.T. (2022). Declarative and procedural memory in second language learning: Psycholinguistic considerations. In A. Godfroid & H. Hopp (Eds.), The Routledge Handbook of Second Language Acquisition and Psycholinguistics. (pp. 322-334) Routledge. 

Morgan-Short, K., Hamrick, P., & Ullman, M. T. (2022). Declarative and Procedural Memory as Predictors of Second Language Development. In S. Li, P. Hiver, M. Papi (Eds.) The Routledge Handbook of Second Language Acquisition and Individual Differences (pp. 67-81). (Supporting Table 1). For link to Supporting Table in Open Science Framework click HERE

Lelonkiewicz, J. R., Ullman, M. T., & Crepaldi, D. (2022). Knowledge of Statistics or Statistical Learning? Readers Prioritize the Statistics of their Native Language Over the Learning of Local Regularities. Journal of Cognition, 5(1) 18, pp. 1–23. 

Karatas, N. B., Özemir, O., Lovelett, J. T., Demir, B., Erkol, K. Veríssimo, J.,  Erçetin, G., and Ullman, M.T. (2021). Improving second language vocabulary learning and retention by leveraging memory enhancement techniques: a multidomain pedagogical approach. Language Teaching Research, 13621688211053525.

Pliatsikas, C., Meteyard, L., Veríssimo, J., DeLuca, V., Shattuck, K., & Ullman, M. T. (2020). The effect of bilingualism on brain development from early childhood to young adulthood. Brain Structure and Function, 225(7), 2131-2152.

Sengottuvel, K., Vasudevamurthy, A., Ullman, M. T., & Earle, F. S. (2020). Learning and Consolidation of Declarative Memory in Good and Poor Readers of English as a Second  Language. Frontiers in Psychology, 11, 715.

Ullman, M. T. (2020). The Declarative/Procedural Model: A Neurobiologically-Motivated Theory of First and Second Language. In B. VanPatten, G. D. Keating, & S. Wulff (Eds.), Theories in Second Language Acquisition (3rd ed., pp. 128-161). Routledge.

Tagarelli, K. M., Shattuck, K. F., Turkeltaub, P. E., & Ullman, M. T. (2019). Language learning in the adult brain: A neuroanatomical meta-analysis of lexical and grammatical learning. NeuroImage, 193, 178-200. (Supplementary Tables).

Nevat, M., Ullman, M. T., Eviatar, Z., & Bitan, T. (2018). The role of distributional factors in learning and generalizing affixal plural inflection: An artificial language study. Language, Cognition & Neuroscience, 33(9), 1184-1204. (Appendix A. Appendix B.)

Hamrick, P., Lum, J. A., & Ullman, M. T. (2018). Child first language and adult second language are both tied to general-purpose learning systems. Proceedings of the National Academy of Sciences, 115(7), 1487-1492. (Supporting Information)

Ullman, M. T., & Lovelett, J. T. (2018). Implications of the declarative/procedural model for improving second language learning: The role of memory enhancement techniques. Second Language Research, 34(1), 39-65.

Grey, S., Sanz, C., Morgan-Short, K., & Ullman, M. T. (2018). Bilingual and monolingual adults learning an additional language: ERPs reveal differences in syntactic processing. Bilingualism: Language and Cognition, 21(5), 970-994. 

Nevat, M., Ullman, M. T., Eviatar, Z., & Bitan, T. (2017). The neural bases of the learning and generalization of morphological inflection. Neuropsychologia, 98, 139-155. 

Hamrick, P., & Ullman, M. T. (2017). A neurocognitive perspective on retrieval interference in L2 sentence processing. Bilingualism: Language and Cognition, 20(4), 687-688.

Ullman, M. T. (2015). The declarative/procedural model: A neurobiologically motivated theory of first and second language. In B. VanPatten & J. Williams (Eds.), Theories in second language acquisition: An introduction (2nd ed., pp. 135-158). Routledge.

Ullman, M. T. (2013). The declarative/procedural model. In P. Robinson (Ed.), Routledge Encyclopedia of Second Language Acquisition (pp. 160-164). Routledge.

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, 2492-2511. (Supplementary Data).

Babcock, L., Stowe, J. C., Maloof, C. J., Brovetto, C., & Ullman, M. T. (2012). The storage and composition of inflected forms in adult-learned second language: A study of the influence of length of residence, age of arrival, sex, and other factors. Bilingualism: Language and Cognition, 15(4), 820-840.

Newman, A. J., Tremblay, A., Nichols, E. S., Neville, H. J., & Ullman, M. T. (2012). The influence of language proficiency on lexical-semantic processing in native and late learners of English: ERP evidence. Journal of Cognitive Neuroscience, 24(5), 1205-1223.

Morgan-Short, K. Finger, I., Grey, S., & Ullman, M. T. (2012). Second language processing shows increased native-like neural responses after months of no exposure. PLoS ONE, 7(3), e32974.

Morgan-Short, K., Steinhauer, K., Sanz, C., & Ullman, M. T. (2012). Explicit and implicit second language training differentially affect the achievement of native-like brain activation patterns. Journal of Cognitive Neuroscience, 24(4), 933-947.

Morgan-Short, K, & Ullman, M. T. (2012). The Neurocognition of second language. In A. Mackey & S. Gass (Eds.), Handbook of Second Language Acquisition (pp. 282-299). Routledge.

Finger, I., Morgan-Short, M., Grey, S., & Ullman, M. T. (2011). SQUIB: Processamento em L2 apresenta ativação neural semelhante à da L1 após meses de ausência de exposição à lingual. Revista LinguíStica, 7(2), 7-17.

Ullman, M. T. (2011). EntreviSta: Michael Ullman. Revista LinguíStica, 7(2), 1-6.

Bowden, H. W., Gelfand, M. P., Sanz, C., & Ullman, M. T. (2010). Verbal Inflectional Morphology in L1 and L2 Spanish: A Frequency Effects Study Examining Storage versus Composition. Language Learning, 60(1), 44-87.

Morgan-Short, K., Sanz, C., Steinhauer, K., & Ullman, M. T. (2010). Second Language Acquisition of Gender Agreement in Explicit and Implicit Training Conditions: An Event-Related Potential Study. Language Learning, 60(1), 154-193.

Ullman, M. T. (2006). The Declarative/Procedural Model and the Shallow-Structure Hypothesis. Applied Psycholinguistics, 27(1), 97-105.   [Commentary on target article by H. Clahsen and C. Felser.]

Ullman, M. T. (2005). A Cognitive Neuroscience Perspective on Second Language Acquisition: The Declarative/Procedural Model. In C. Sanz (Ed.), Mind and Context in Adult Second Language Acquisition: Methods, Theory, and Practice (pp. 141-178). Georgetown University Press.

Ullman, M. T. (2004). Contributions of neural memory circuits to language: The declarative/procedural model. Cognition, 92(1-2), 231-270.

Ullman, M. T. (2001). The neural basis of lexicon and grammar in first and second language: The declarative/procedural model. Bilingualism: Language and Cognition, 4(1), 105-122.