Research on bilingualism has boomed in the past two decades. The processes by which
a second language is acquired and processed has been investigated via linguistic,
psycholinguistic, and neurolinguistic perspectives, focusing not only on second language
(L2) acquisition and processing, but also the effects it might have on cognition and
brain structure and function (Bialystok et al., 2012). More recent studies have focused
on the effects of experience-based factors on L2 acquisition and processing (Dussias
and Piñar, 2009); for example, several studies have increasingly focused on how L2
processing is affected by the active and continuous use of L2, or immersion, whether
it becomes native-like, and which language domains are particularly affected (Dussias
and Sagarra, 2007; Pliatsikas and Marinis, 2013). The present E-Book is a collection
of recent studies that demonstrate the effects of immersive L2 learning in lexical,
phonological and morpho-syntactic processing, while at the same time discusses the
potential effects of immersive non-native acquisition on the structure of the bilingual
brain.
Several studies in this E-Book have focused on morpho-syntactic processing by immersed
late L2 learners. In an ERP study, Carrasco-Ortiz and Frenck-Mestre (2014) showed
that highly proficient L2 learners of French with limited immersion (5–6 months) were
native-like in their sensitivity of detecting verbal inflectional errors. This sensitivity
was enhanced in the presence of phonological cues to the errors, but was also dependent
on the L2 learner's overall proficiency. Further evidence in the domain of morpho-syntax
was provided in an ERP experiment by Meulman et al. (2014), who demonstrated that
immersed (5 years) late Romance learners of Dutch were native-like in detecting auditorily-presented
verb agreement violations in non-finite verbs, but not gender violations. This demonstrated
that there might be limits to how native-like L2 processing can be, but these limits
are specific to the grammatical construction under investigation.
In two behavioral masked lexical priming experiments and in an ERP study with advanced
Spanish and German late L2 learners of English, De Cat et al. (2015) showed that lexically
transparent noun-noun compounds (NNCs) such as moon dust are processed combinatorially
by advanced non-native speakers similarly to native speakers; however, sensitivity
to word order violations within the NNCs was modulated by the learners' L1.
In an acceptability judgment task, Parafita Couto et al. (2015) examined the interaction
between word order and focus in the context of unaccusative (e.g., arrive) and unergative
(e.g., walk) verbs in Spanish in a group of English late L2 learners of Spanish with
extensive naturalistic exposure to L2 input. Immersed late L2 learners accepted different
word order patterns depending on the focus context; however, they failed to distinguish
between unaccusative and unergative verbs, and the ability to do so was a function
of the verb's frequency rather than its categorical classification on the basis of
unaccusativity. At the same time, L2 learners were less categorical in their judgments
compared to monolingual speakers.
In terms of lexical recognition, in two behavioral experiments, Casaponsa et al. (2014)
demonstrated that immersed balanced and unbalanced Spanish-Basque bilinguals were
equally efficient in recognizing L2-specific bigrams, suggesting that bilingual immersion
can lead to native-like orthographic processing; however, these effects were modulated
by the participants' L2 proficiency.
Zinszer et al. (2014) tested Chinese-English bilinguals in China and in the US on
a lexical categorization task and examined which L2 learner's language history variables
(length of immersion, L2 training, age of L2 onset, and code-switching patterns) and
language variables (e.g., native speaker agreement on picture naming) predict performance
on this task. The authors reported that words with high name agreement and few alternate
names elicited high performance; at the same time, immersion, age of L2 onset and
code-switching patterns contributed positively to learners' performance, whereas years
of L2 training had a negative impact on task performance.
The effects of exposure to naturalistic L2 input on vocabulary learning were examined
in two studies by Dahl and Vulchanova (2014) and by Vulchanova et al. (2015). Dahl
and Vulchanova examined whether providing naturalistic L2 exposure within a standard
school curriculum influences comprehension of vocabulary in two groups of 6-year-old
Norwegian-speaking children. After 8 months of exposure, the group that received naturalistic
input to English outside the classroom setting but within the school context outperformed
on vocabulary learning the group that was only exposed to English within the classroom
setting. This suggests that increased exposure to the L2 can lead to a significant
increase in receptive vocabulary at this young age even after a short period.
Vulchanova et al. (2015) examined short- and long-term memory effects of first language
(L1) and L2 subtitles on text comprehension and vocabulary learning in two groups
of adolescent Norwegian learners of English. Short-term effects of L1 and L2 subtitles
on text comprehension were found in both groups. These effects were modulated by vocabulary
knowledge in the younger group of L2 learners and by knowledge of grammar in the older
L2 group. There were no long-term effects in either group on vocabulary learning as
measured through a word definition task and lexical decision task. Participants' extracurricular
activities such as reading and writing in the L2, exposure to L2 media and games also
emerged as significant predictors of the L2 learners' comprehension abilities.
In terms of phonological processing, Gor (2014) demonstrated that heritage English-Russian
speakers (early naturalistic interrupted learners) of high proficiency in Russian,
were equally efficient to native speakers of Russian in processing speech in noise.
This demonstrated the early benefits of immersed L2 learning, which appear to persevere
even when immersion is interrupted.
Although the existing behavioral and ERP literature appears to argue for substantial
effects of immersion on bilinguals' performance, its effects on brain structure are
proven more difficult to capture and describe. In an opinion article, Sharwood Smith
(2014) discusses the issues in combining linguistic, psychological and neuroimaging
approaches in the search for a unified theory of bilingual processing. In reviewing
the neurolinguistic literature, Stein et al. (2014) argue that the reported structural
effects of bilingualism on the gray matter (GM) and white matter (WM) of the brain
cannot be safely attributed to the type or amount of L2 immersion, although it appears
that immersion is more likely to have an impact on the WM (see also Pliatsikas et
al., 2015). The effects of bi-/multilingualism on the GM are further demonstrated
in a structural MRI study by Kaiser et al. (2015). In this study, possibly the first
of its kind on multilinguals, it is suggested that successive L2 learning leads to
more extended changes in GM compared to early simultaneous language learning. This
effect persists even in individuals that learn a third language later in life, suggesting
that early immersive bilingualism might lead to more effective synaptic connectivity
for language learning, which in turn leads to less profound structural changes during
late learning of additional languages.
Taken together, the papers in this E-book demonstrate the role and the importance
of experienced-based factors, and especially linguistic immersion, for the acquisition
and processing of a second or a third language. We hope that this E-book will inspire
researchers to pay particular attention to the environmental factors that shape the
linguistic experiences of their non-native participants, and to present comprehensive
descriptions of their groups' linguistic background, including detailed information
about their bi-/multilingual immersion.
Conflict of interest statement
The authors declare that the research was conducted in the absence of any commercial
or financial relationships that could be construed as a potential conflict of interest.