A selection from Stockholm University publication database

• The irreversibility of sensitive period effects in language development

  2016. Gunnar Norrman, Emanuel Bylund. Developmental Science 19 (3), 513-520

  Article

  The question of a sensitive period in language acquisition has been subject to extensive research and debate for more than half a century. While it has been well established that the ability to learn new languages declines in early years, the extent to which this outcome depends on biological maturation in contrast to previously acquired knowledge remains disputed. In the present study, we addressed this question by examining phonetic discriminatory abilities in early second language (L2) speakers of Swedish, who had either maintained their first language (L1) (immigrants) or had lost it (international adoptees), using native speaker controls. Through this design, we sought to disentangle the effects of the maturational state of the learner on L2 development from the effects of L1 interference: if additional language development is indeed constrained by an interfering L1, then adoptees should outperform immigrant speakers. The results of an auditory lexical decision task, in which fine vowel distinctions in Swedish had been modified, showed, however, no difference between the L2 groups. Instead, both L2 groups scored significantly lower than the native speaker group. The three groups did not differ in their ability to discriminate non-modified words. These findings demonstrate that L1 loss is not a crucial condition for successfully acquiring an L2, which in turn is taken as support for a maturational constraints view on L2 acquisition.

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• Revisiting the bilingual lexical deficit: The impact of age of acquisition

  2019. Emanuel Bylund (et al.). Cognition 182, 45-49

  Article

  Whereas the cognitive advantages brought about by bilingualism have recently been called into question, the so-called ‘lexical deficit’ in bilinguals is still largely taken for granted. Here, we argue that, in analogy with cognitive advantages, the lexical deficit does not apply across the board of bilinguals, but varies as a function of acquisition trajectory. To test this, we implement a novel methodological design, where the variables of bilingualism and first/second language status have been fully crossed in four different groups. While the results confirm effects of bilingualism on lexical proficiency and processing, they show more robust effects of age of acquisition. We conclude that the traditional view of the linguistic costs of bilingualism need to give way to a new understanding of lexical development in which age of acquisition is seen as a major determinant.

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• Long-term language development in international adoptees

  2016. Gunnar Norrman, Kenneth Hyltenstam, Emanuel Bylund. Starting Over – The Language Development in Internationally-Adopted Children, 125-146

  Chapter

  The linguistic development of internationally adopted children has been studied extensively for several decades. Whereas this research has mainly concerned toddlers and pre-school children during their first years after adoption, school-age children, and adolescents, there is currently scarce empirical evidence on the long-term linguistic development in adults with adoption background. While studies of infants and pre-school children generally show fast and positive short-term progress in linguistic development, medium-term studies (4–10 years after adoption) describe adoptees as still “lagging behind” their non-adopted peers. This chapter reviews the studies to date on long-term outcomes in the linguistic development of adoptees. What happens after more than ten years of exposure and into adulthood? From the review, we conclude that slight differences between adopted and non-adopted L1 speakers of a language often remain into adulthood. In addition, the limited evidence that exists to date suggests that adults who at a young age emigrated with their families to the L2 environment, and therefore continued to develop their L1, exhibit similar levels of L2 proficiency as internationally adopted adults. However, more research is required to further substantiate and generalize the conclusions that are made on the basis of our review.

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• Age and Constraints on Language Learning

  2020. Gunnar Norrman.

  Thesis (Doc)

  This thesis investigates the influence of age of acquisition on the long-term second language development of international adoptees. Because age of acquisition typically coincides with the onset of bilingualism, the study of maturational age effects in second language acquisition has been empirically and conceptually entangled with changes in language input and use. For international adoptees, however, because the adoptive language is acquired under similar linguistic conditions as non-adopted peers – albeit at a later age of acquisition – questions of age and second language acquisition can be investigated without confounding influences of bilingualism. Study I presents the theoretical argument that, because of the delay in acquisition, the language development of international adoptees should be regarded as a special case of second language acquisition. Furthermore, consistent with the contemporary study of second language acquisition, the effects of this delay should be investigated through ultimate attainment observed in adults. Study II shows that adults in Sweden who had been adopted from Spanish-speaking countries, and Spanish-Swedish bilinguals with the same age of acquisition (3-8 years), have greater difficulty in perceiving Swedish vowel distinctions that do not exist in Spanish compared to native Swedish speakers. This suggests that age of acquisition is a decisive factor for speech perception in a second language. In Study III, Chinese-Swedish adoptees are found to deviate from native Swedish speakers in their production of Swedish vowels that are phonologically identical in Chinese, but not in vowels that are distinctive in both languages. While these results are consistent with predictions based on assumptions of transfer and interference in bilingual speakers, they cannot be explained based on these premises. Instead, the results suggest that early language-specific experiences will affect the pronunciation of vowels in the second language regardless of whether the native language is in use or not. In Study IV, the neural underpinnings of the behavioral results are investigated electrophysiologically, using EEG. This study shows that adult adoptees retain increased neural sensitivity to a native Chinese lexical tone contrast without any exposure to the language for over 15 years. This is reflected in a fast neural response stemming from the auditory cortex and is indexed by the mismatch negativity event-related potential. This suggests that native language sensitivity is not only retained, but is continuously involved in the moment-to-moment processing of speech sounds. Neural oscillations furthermore reveal the involvement of inhibitory processes to attenuate this sensitivity. Finally, positive correlations between neural responses to the native and the adoptive language show that native language retention is not in itself an impediment for second language acquisition. The results from these three studies show how language-specific experiences lead to irreversible specialization in the brain, which will affect the long-term acquisition of a second language. This finding invites a re-evaluation of the hypothesis of a critical period for second language acquisition, based on the notions of probabilistic epigenesis and flexible behavioral adaptation following experience-based functional neural reorganization in early childhood.

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