As we’ve been talking about mental grammar, we’ve concentrated almost entirely on the mental grammar of your native language — the language you learned to speak in childhood, in your home. Linguists refer to your native language, your first language, as your L1. But many people in the world speak more than one language, and many of those people learned a second or third language in a different way from their L1. Any language that you learned after childhood, whether you learned it in school, using software, by travelling or immigrating somewhere, is called an L2 (even if it’s really your third or fourth language).
Learning an L2 is different from learning an L1 for a couple of different reasons. One is that, obviously, the language learner is not a child, so their cognitive processes might be different from those of a child. L1 learning happens by being immersed in a language environment, and most of the learning is unconscious, without overt teaching. L2 learning often happens with a lot of conscious effort: studying and memorizing and practicing.
But of course, the biggest difference between L1 learning and L2 learning is that when you start learning an L2, you already know at least one other language. The mental grammar of your L1 can influence the mental grammar that you’re developing for your L2: this is called transfer. Transfer can be helpful in L2 learning or it can pose a challenge. If your L1 includes a structure that’s similar to a structure in the L2, then you might experience positive transfer, which facilitates learning the L2: you can transfer what you know from L1 and apply it to the L2. But if the structures that you’re learning in L2 are different from those in your L1, then you might experience negative transfer: the knowledge from your L1 could make it more difficult to learn the new structures in the L2. And of course, you might experience both positive and negative transfer from your L1 to different parts of the grammar of your L2.
One theory of second language acquisition predicts that we would observe differences between native speakers and beginner L2 learners, but as the L2 learners become more proficient, their mental processes should become more and more native-like — that is the mental grammar of a fluent L2 speaker should look very similar to the mental grammar of an L1 speaker of that language. We can use the tools of psycholinguistics and neuroscience to learn about the mental grammars of L2 learners. Let’s take a look at some of the evidence.
Several studies have compared N400 effects in L1 and L2 speakers of a language. Remember that the N400 is an electrophysiological response that our brains show when a word is semantically unexpected in a given context. The brains of native speakers of English show a negative voltage about 400 milliseconds after a semantically unexpected word (socks), compared to an expected word. But what do the brains of non-native speakers show? What do we see in L2 learners?
A 2001 paper by Anja Hahne compared L1 speakers of German with L1 speakers of Russian who had moved to Germany in their 20s and had been living there and studying German for an average of six years. The experiment used fairly simple German sentences like these ones:
Die Tür wurde geschlossen / The door was being closed.
Der Ozean wurde geschlossen / The ocean was being closed.
Obviously, the word closed is a reasonable way for the first sentence to end but is a pretty unexpected way for the second sentence to end. So it’s not surprising that the native speakers of German showed an N400 in response to sentence 2 compared to sentence 1. The L2 speakers, the ones who had started learning German in their 20s, also showed an N400 to sentence 2. Hahne concluded that words that are semantically unexpected cause “essentially similar semantic integration problems in native participants and second-language learners” (Hahne, 2001: 263). In other words, the evidence from the N400 suggests that the lexical semantic component of an L2 learner’s mental grammar is not too different from that of an L1 grammar.
Now, we know that there’s a whole lot more to mental grammar than just the meanings of words. What can ERPs tells us about morphology and syntax? Remember that native speakers’ brains often show a P600 response to sentences that are syntactically unexpected. For many years, studies that looked at the P600 in L2 learners seemed to suggest that adult language learners never really approached native-like proficiency in their L2 morphosyntax: the P600 response to syntactic violations was significantly delayed or not there at all in these late learners. But some more recent research has suggested that maybe those earlier studies just didn’t give the learners enough time to learn their L2 — of course, their mental grammar wasn’t native-like if they hadn’t been learning the language for very long.
A 2013 study by Harriet Bowden and her colleagues looked at L1 English speakers who started learning L2 Spanish in university. They compared learners who had completed first-year Spanish to learners who had completed more than three years of university Spanish and had spent a year abroad. And they included a control group of L1 speakers of Spanish. The researchers presented Spanish sentences that violated syntactic expectations about word order like these ones. Sentence 1, “I have to run many miles this week” has the expected word order, while sentence 2, “I have to miles many run this week” is unexpected in its word order: the quantifier many comes after the noun miles, and that whole complement phrase comes before the verb run. Sentence 2 is ungrammatical in Spanish.
As you’d expect, the native speakers of Spanish showed a P600 in response to the ungrammatical sentence. But so did the advanced L2 learners: their ERP response was the same as that of the L1 Spanish speakers. It was only the beginning learners, the ones who had had only a year of Spanish, who showed an atypical P600: it was a smaller response and more diffuse. The researchers concluded that “University foreign-language learners who take L2 classes through much of college and also study abroad for one or two semesters …show evidence of native-like brain processing of syntax” (Bowden et al., 2013: 2508).
So this study suggests that one year of studying a language maybe isn’t enough to achieve native-like fluency, and three years of study including a year of immersion allows a learner to approach native proficiency, but the researchers also wondered whether the kind of language-learning makes a difference to learners. If you’re learning a language in university, you probably spend three or four hours a week in the classroom, and maybe two or three more hours each week studying. But that’s not the only way to learn a language.
A study in Montreal looked at university students who were L1 speakers of Korean and Chinese who were enrolled in a nine-week intensive English L2 course. These learners were studying, practising, using English at least 8-10 hours a day, five days a week, for nine weeks. The researchers tested the learners on sentences with morphosyntactic violations in the tense features on the verb, like these ones:
1a. The teacher did not start the lesson / 1b. The teacher did not started the lesson.
2a. The teacher had not started the lesson / 2b. The teacher had not start the lesson.
Notice that in 1b and 2b, the verb has unexpected morphology on it. A native speaker of English would show a P600 response to 1b and 2b in comparison to 1a and 2a. In this study, the researchers measured learners’ ERP responses at the beginning of the course and after the nine weeks, and they also asked the learners to judge whether the sentences were grammatical. At the beginning of the course, none of the learners showed P600s in response to the syntactically unexpected sentences, and they also weren’t very successful at deciding whether sentences were grammatical or ungrammatical. After the nine-week course, all of the learners showed P600 responses to the syntactically unexpected sentences, and the learners who scored highest on the grammatical judgments showed the largest P600s. This study suggests that even short-term, intensive L2 learning can help a learner develop a mental grammar that approaches that of a native L1 speaker.
And the results of all of these studies tell us that L2 language learners can achieve fluency that compares to that of a native speaker; it just takes lots of training to get there!