A Meta‐analysis of Hemodynamic Studies on First and Second Language Processing: Which Suggested Differences Can We Trust and What Do They Mean?

Abstract

This article presents the results of a meta-analysis of 30 hemodynamic experiments comparing first language (L1) and second language (L2) processing in a range of tasks. The results suggest that reliably stronger activation during L2 processing is found (a) only for task-specific subgroups of L2 speakers and (b) within some, but not all regions that are also typically activated in native language processing. A tentative interpretation based on the functional roles of frontal and temporal regions is suggested.In recent years, there has been an increasing number of neurocognitive studies investigating language processing in bilingual speakers. Most researchers interested in language are aware of one or another study reporting hemodynamic activation differences between first language (L1) and second language (L2) processing. Given the plethora of experimental details that might lead to signal changes in hemodynamic experiments, however, differences as such might not mean very much as long as they do not overlap across studies with similar paradigms and as long as it is not clear which factors determine the presence or absence

Speaking in multiple languages: Neural correlates of language proficiency in multilingual word production

“…As the left IFG is involved in several language tasks including phonetic, syntactic and semantic processing (Indefrey and Levelt 2000), its specific importance for processing a less fluently spoken L2 has not been unequivocally determined yet. It has been proposed that particularly the posterior portions of IFG subserve syllabification of speech which is more demanding for languages spoken at a low proficiency level (Indefrey 2006). Alternatively, Abutalebi and colleagues (Abutalebi & Green 2007;Abutalebi 2008;Abutalebi & Green 2008) proposed in their language control theory of bi-und multilingualism that enhanced left inferior prefrontal activation for low proficient languages reflects the increased demands on cognitive control processes.…”

“…Illes et al 1995;Chee et al 1999;Hernandez et al 2000Hernandez et al , 2001Rodriguez-Fornells et al 2005), a stronger recruitment of some brain areas for the later acquired and less fluently spoken languages has been sometimes obtained. One of the most robust findings is the stronger involvement of left inferior prefrontal areas, including the inferior frontal gyrus, in the production and comprehension of languages that are spoken at a relatively low proficiency level (Indefrey 2006;Abutalebi & Green 2007;Abutalebi 2008;Abutalebi & Green 2008).…”

“…generally recruits the network of classical language areas in inferior frontal and temporo-parietal cortex that also subserves L1 (Indefrey 2006;Abutalebi & Green 2007;Abutalebi 2008). While several neuroimaging studies found entirely overlapping activation patterns for the first and further Videsott et al: Neural correlates of language proficiency 4 languages in production and comprehension tasks (e.g.…”

“…In fact, previous neuroimaging studies suggested an influence of these variables for the neural representation of multiple languages and particularly emphasized the role of language proficiency (for a review see Abutalebi 2008;Kotz 2009). Although a lot of progress has been made in elucidating the brain structures underlying multilingualism (Perani & Abutalebi, 2005;Indefrey 2006;Abutalebi, 2008), the role of proficiency has to be better enlightened.…”

An MEG study of the spatiotemporal dynamics of bilingual verb generation

“…Historically, some studies have reported distinct neural representations suggesting spatially separate networks for multiple languages; others have reported overlapping areas controlled by a common, integrated neural network for bilingual or multilingual use; the current working model assumes that bilingual language processing is not subsumed in spatially distinct areas, but different languages show functional distinctions in the brain (Abutalebi, 2008). A paper reporting the results of a meta-analysis of hemodynamic studies of bilingualism points to the huge variability in the literature, and suggests that this is primarily due to differences in experimental parameters; however, the author concludes that despite these limitations, there are differences in the activation patterns between L1 and L2 that likely are not due to coincidence although the factors of L2 onset, proficiency and exposure need to be controlled and consistent between subjects (Indefrey, 2006). These same issues have been raised in more recent reviews also (Kotz, 2009;Leonard, et al, 2010).…”