We investigated age-related decline in adult learning of Dutch as an additional language (Ln) in speaking, writing, listening, and reading proficiency test scores for 56,024 adult immigrants with 50 L1s who came to the Netherlands for study or work. Performance for all four language skills turned out to decline monotonically after an age of arrival of about 25 years, similar to developmental trajectories observed in earlier aging research on additional language learning and in aging research on cognitive abilities. Also, linguistic dissimilarity increased age-related decline across all four language skills, but speaking in particular. We measured linguistic dissimilarity between first languages (L1s = 50) and Dutch (Ln) for morphology, vocabulary, and phonology. Our conclusion is that the L1 language background influences the effects of age-related decline in adult language learning, and that the constraints involved reflect both biological (language learning ability) and experience-based (acquired L1 proficiency) cognitive resources.

我们调查了 56,024 名来荷兰学习或工作的 L1 成绩为 50 的成年移民，荷兰语作为附加语言 (L n ) 在口语、写作、听力和阅读能力测试分数方面的成人学习下降与年龄相关。所有四种语言技能的表现在大约 25 岁之后单调下降，类似于早期关于额外语言学习的老化研究和认知能力的老化研究中观察到的发展轨迹。此外，语言差异加剧了所有四种语言技能与年龄相关的衰退，尤其是口语。我们测量了母语 (L1s = 50) 和荷兰语 (L n) 用于词法、词汇和音系。我们的结论是，L1 语言背景会影响成人语言学习中与年龄相关的衰退的影响，并且所涉及的限制反映了生物学（语言学习能力）和基于经验（获得的 L1 熟练程度）的认知资源。