Document Type : Research article


Assistant Professor, Department of English Language, Lamerd Branch, Islamic Azad University, Lamerd, IRAN


This study explores the extent to which adult Second Language (L2) Learners of English are sensitive to Subject-Verb (S-V) agreement errors with thematic verbs and copulas. A group of intermediate-to-advanced Persian-English second language learners and a group of native English speakers (NSs) participated in an online Speeded Acceptability Judgment task. The results are as follows. Whereas NSs are sensitive to number agreement errors in both verb types, second language learners are not. For the latter group, the results reveal the following systematic errors. For agreement errors in thematic verbs, there is an omission-commission asymmetry; whereas L2 learners are not sensitive to omission errors, they are sensitive to commission errors in finite forms. For copulas, there is a singular-plural asymmetry, indicating higher error rates in *plural subject NP + is configurations than in *singular subject NP+ are ones. Yet, proficiency seems to be a strong predictor of L2 learners’ sensitivity to agreement errors. The results support the Morphological Underspecification Hypothesis (McCarthy, 2007; 2008; 2012).


  1. Allan, D. (1992). The Oxford Placement Test (2nd Edition). Oxford University Press.
  2. Armstrong, A., Bulkes, N., & Tanner, D. (2018). Quantificational cues modulate the processing of English subject-verb agreement by native Chinese speakers: An ERP study. Studies in Second Language Acquisition, 40(4), 731-754.
  3. Baayen, R. H. (2008). Analyzing linguistic data. A practical introduction to statistics using R. Cambridge: Cambridge University Press.
  4. Barr, D. J., Levy, R., Scheepers, C., & Tily, H. J. (2013). Random effects structure for confirmatory hypothesis testing: Keep it maximal. Journal of Memory and Language, 68(3), 255-278.
  5. Blom, E., & Baayen, H. R. (2012). The impact of verb form, sentence position, home language and proficiency on subject-verb agreement in child L2 Dutch. Applied Psycholinguistics, 34(4), 777-811.
  6. Chen, L., Shu, H., Liu, Y., Zhao, J., & Li, P. (2007). ERP signatures of subject-verb agreement in L2 learning. Bilingualism: Language and Cognition, 10(2), 161-174.
  7. Cowper, E. (2005). The geometry of interpretable features: Infl in English and Spanish. Language, 81(1), 10-46.
  8. Davies, M. (2008). The Corpus of Contemporary American English: 450 million words, 1990-present. Retrieved from Available online at
  9. Ellis, R. (2005). Measuring implicit and explicit knowledge of a second language: A psycholinguistic study. Studies in Second Language Acquisition, 27, 141-172.
  10. Eubank, L., & Grace, S. T. (1998). V-to-I and inflection in non-native grammars. In M.-L. Beck (Ed.), Morphology and its interfaces in L2 knowledge (pp. 69-88). John Benjamins.
  11. Forster, K., & Forster, J. (2003). DMDX: A Windows display program with millisecond accuracy. Behavior Research Methods, Instruments, & Computers, 35(1), 116-124.
  12. Franceschina, F. (2005). Fossilized second language grammars: The acquisition of grammatical gender. John Benjamins.
  13. Franck, J., Lassi, G., Frauenfelder, U., & Rizzi, L. (2006). Agreement and movement: A syntactic analysis of attraction. Cognition, 101, 173-216.
  14. Harley, H. (1994). Hug a tree: deriving the morphosyntactic feature geometry. In A. Carnie, H. Harley, & T. Bures (Eds.), MIT Working Papers in Linguistics (Vol. 21, pp. 289–320).
  15. Harley, H., & Ritter, E. (2002). Person and number in pronouns: A feature-geometric analysis. Language, 78(3), 482-526.
  16. Hawkins, R., & Chan, C. (1997). The partial availability of Universal Grammar in second language acquisition: The ‘failed functional feature hypothesis’. Second Language Research, 13(3), 187-226.
  17. Herschensohn, J. (2001). Missing inflection in L2 French: Accidental infinitives and other verbal deficits. Second Language Research, 17(3), 273-305.
  18. Hothorn, T., Hornik, K., & Zeileis, A. (2006). Unbiased recursive partitioning: A conditional inference framework. Journal of Computational and Graphical Statistics, 15(3), 651–674.
  19. Ionin, T., & Wexler, K. (2002). Why is ‘is’ easier than ‘-s’?: Acquisition of tense/agreement morphology by child second language learners of English. Second Language Research, 18(2), 95-136.
  20. Jaeger, T. F. (2008). Categorical data analysis: Away from ANOVAs (transformation or not) and towards logit mixed models. Journal of Memory and Language, 59(4), 434–446.
  21. Jiang, N. (2004). Morphological insensitivity in second language processing. Applied Psycholinguistics, 25(4), 603-634.
  22. Lago, S., & Felser, C. (2018). Agreement attraction in native and non-native speakers of German. Applied Psycholinguistics, 39(1), 619–647.
  23. Lardiere, D. (2007). Ultimate attainment in second language acquisition: A case study. Mahwah, NJ: Erlbaum.
  24. Lim, J. H., & Christianson, K. (2015). Second language sensitivity to agreement errors: Evidence from eye movements during comprehension and translation. Applied Psycholinguistics, 36(6), 1283-1315.
  25. López Prego, B., & Gabriele, A. (2014). Examining the impact of task demands on morphological variability in native and non-native Spanish. Linguistic Approaches to Bilingualism, 4(2), 192–221.
  26. McCarthy, C. (2007). Morphological variability in second language Spanish [Unpublished doctoral dissertation]. McGill University, Montreal.
  27. McCarthy, C. (2008). Morphological variability in the comprehension of agreement: An argument for representation over computation. Second Language Research, 24(4), 459-486.
  28. McCarthy, C. (2012). Modeling morphological variation and development: Person and number in L2 Spanish. Linguistic Approaches to Bilingualism, 2(1), 25-53.
  29. McDonald, J. L. (2006). Beyond the critical period: Processing-based explanations for poor grammaticality judgment performance by late second language learners. Journal of Memory and Language, 55(3), 381-401.
  30. McElree, B., & Griffith, T. (1995). Syntactic and thematic processing in sentence comprehension: Evidence for a temporal dissociation. Journal of Experimental Psychology: Learning, Memory, and Cognition, 21(1), 134-157.
  31. Ojima, S., Nakata, H., & Kakigi, R. (2005). An ERP study of second language learning after childhood: Effects of proficiency. Journal of Cognitive Neuroscience, 17(8), 1212-1228.
  32. Pearlmutter, N. J., Garnsey, S. M., & Bock, K. (1999). Agreement processes in sentence comprehension. Journal of Memory and Language, 41(3), 427-456.
  33. Prévost, P., & White, L. (2000). Missing surface inflection or impairment in second language acquisition? Evidence from tense and agreement. Second Language Research, 16(2), 103-133.
  34. R Development Core Team. (2017). R: A language and environment for statistical computing: R Foundation for Statistical Computing, Vienna, Austria. Retrieved from
  35. Radford, A. (2009). Analysing English Sentences: A Minimalist Approach. Cambridge: Cambridge University Press.
  36. Rossi, S., Gugler, M. F., Friederici, A. D., & Hahne, A. (2006). The impact of proficiency on syntactic second-language processing of German and Italian: Evidence from event-related potentials. Journal of Cognitive Neuroscience, 18(12), 2030-2048.
  37. Safaie, E. (2015). Sensitivity to subject-verb agreement in second language sentence processing: Evidence from L1 Persian speakers of L2 English [Unpublished doctoral dissertation]. The University of Essex, Colchester.
  38. Safaie, E. (2020). Frequency effects of regular past tense forms in English on native speakers’ and second language learners’ accuracy rate and reaction time. Journal of Teaching Language Skills, 39(1), 153-199.
  39. Safaie, E. (2021). Sensitivity to regular and irregular past tense morphology in native speakers and second language learners of English: Evidence from intermediate-to-advanced Persian speakers of L2 English. Journal of Psycholinguistic Research, 50, 1107-1135.
  40. Sato, M., & Felser, C. (2010). Sensitivity to morphosyntactic violations in English as a second language. Second Language, 9, 101-118.
  41. Schütze, C. T. (1996). The empirical base of linguistics: Grammatical judgments and linguistic methodology. Chicago: University of Chicago Press.
  42. Slabakova, R. (2009). How is inflectional morphology learned? EuroSLA Yearbook, 9(1), pp. 56-75.
  43. Tanner, D., Nicol, J., Herschensohn, J., & Osterhout, L. (2012). Electrophysiological markers of interference and structural facilitation in native and nonnative agreement processing. In A. K. Biller, E. Y. Chung, & A. E. Kimball (Eds.), Proceedings of the 36th Boston University conference on language development (pp. 594-606). Cascadilla.
  44. Wakabayashi, S. (1997). The acquisition of functional categories by learners of English. [Unpublished doctoral dissertation]. The University of Cambridge, Cambridge.