This investigation aimed to provide insights into the controversial debate on the role that age at onset of bilingualism plays in human language capacity with a focus on what it entails for first language (L1) attrition. L1 performance of Turkish immigrants (n = 57) in the United Kingdom with age at onset ranging between 7 and 34 years was compared to that of Turkish monolingual controls (n = 29) across two linguistic properties: structural complexity and accent. Findings generally showed that although the immigrants achieved nativelike proficiency with respect to the overall structural complexity of their L1, this was not the case for accent as those with an earlier age of onset were less likely to sound like native Turkish speakers. We discuss these findings in relation to two competing theoretical models of age effects and suggest that attrition data need to be better accommodated within these models. Open Practices This article has been awarded an Open Materials badge. All materials are publicly accessible via the IRIS Repository at https://www.iris-database.org. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki.

Recent decades have seen an increase in research informing our understanding of the complex ways in which bilingual development is shaped by biological, cognitive, and behavioral factors. We investigate the predictors that shape, drive, and constrain the development of the first language (L1) of bilinguals, focusing on 92 Turkish–English bilingual adults with a wide range (0–42) of age at onset (AaO). We tested their productive command of L1 lexical, morphological, and syntactic features, investigating to what extent background variables relating to AaO, experience, and attitudes toward the Turkish language and culture predict the relative level of proficiency across these features. To obtain a comprehensive picture of the interaction of these linguistic and extralinguistic factors, we employed structural equation modeling. We show that for speakers with younger AaOs, exposure‐related factors are associated with the level of L1 proficiency they retain as adults; for later bilinguals, exposure‐related factors matter less.

Adopting a usage-based perspective, the present study assesses the mental lexicon of Turkish heritage speakers in the UK (HSs, n = 31) regarding the productive use of formulaic inflectional suffix templates and the level of sophistication of the lemmas produced in free speech. We additionally explore input-related predictors of this performance by comparing HS performance to that of a group of previous generation immigrant bilinguals (IBs, n = 61), who are representative input providers, and of a group of monolinguals (n = 44). The results show that overall, both the HSs and IBs diverge from the monolinguals in that they use nominal suffix sequences less productively and rely on less sophisticated nominal lemmas. Their verbal productivity performance, however, remains intact. We argue that altered input results in a performance which diverges from that of the monolinguals but converges on the immigrant variety. The individual variability is partly explained by the amount of L1 passive exposure, indicating that the HSs are not sensitive only to the changes in the input available to them but also to the amount of it. These findings provide new insights into the line of research that describes HSs as incomplete due to their L1-divergent skills in comparison to a monolingual baseline.

This volume is the first handbook dedicated to language attrition, the study of how a speaker’s language may be affected by cross-linguistic interference and non-use. The effects of language attrition can be felt in all aspects of language knowledge, processing, and production, and can offer unique insights into the mind of bilingual language users. In this book, international experts in the field explore a comprehensive range of topics in language attrition, examining its theoretical implications, psycho- and neurolinguistic approaches, linguistic and extralinguistic factors, second language (L2) attrition, and heritage languages. The chapters summarize current research and draw on insights from related fields such as child language development, language contact, language change, pathological developments, and second language acquisition.

This study investigates the spoken performance of UK based adult heritage speakers (HSs) and first generation immigrants (LBs) of Turkish descent regarding the distribution of evidentiality encoded in the past tense system of Turkish. Additionally, we trace the effect of input quality and quantity on the development of the heritage language (HL). The analyses suggest that the ability to differentiate between different evidential structures is unstable in HL grammars. There are no signs of qualitatively modified input available to the HSs through the LBs. This performance is instead linked to the amount of input, which has been found to be insufficient to compensate for the detrimental effects of early bilingualism on the HL. Findings are discussed within the premises of available approaches to heritage language bilingualism.