Smolander Sini, Laasonen Marja, Arkkila Eva, Lahti-Nuuttila Pekka, Kunnari Sari
Department of Otorhinolaryngology and Phoniatrics, Head and Neck Surgery, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
Research Unit of Logopedics, University of Oulu, Oulu, Finland.
Int J Lang Commun Disord. 2021 Jan;56(1):72-89. doi: 10.1111/1460-6984.12583. Epub 2020 Nov 12.
Language exposure is known to be a key factor influencing bilingual vocabulary development in typically developing (TD) children. There is, however, a lack of knowledge in terms of exposure effects in children with developmental language disorder (DLD) and, especially, in interaction with age of onset (AoO) of second language acquisition.
In the Helsinki longitudinal SLI study (HelSLI), we investigated the receptive and expressive second language (L2) vocabulary performance and cross-sectional vocabulary development of sequentially bilingual children with TD and DLD in order to resolve whether the groups could be differentiated based on their vocabulary performance. More importantly, we examined the effects of AoO and exposure in the vocabulary performance of these two bilingual groups.
METHODS & PROCEDURES: A total of 70 children with DLD from a hospital clinic and 82 with TD from kindergartens were recruited. Children were 3-7 years old with different AoOs for the L2 and varying degrees of language exposure. Multiple regression analysis was used to compare the groups in two receptive and three expressive vocabulary tests while considering the effects of AoO and language exposure.
OUTCOMES & RESULTS: Children with TD outperformed children with DLD in both receptive and expressive vocabulary measures. Exposure predicted vocabulary but AoO did not. The effect of exposure was different in TD and DLD groups in receptive but not in expressive vocabulary. Additionally, the interaction of exposure and AoO was found for receptive vocabulary, but similarly in both groups. With increasing exposure, a difference in performance between the groups became more notable in receptive vocabulary compared with the expressive vocabulary.
CONCLUSIONS & IMPLICATIONS: Bilingual children with TD and DLD can be differentiated by using L2 vocabulary tests when exposure is taken into consideration. Non-significant AoO effects in 3-7 year olds suggest flexibility in terms of when to start L2 immersion. However, exposure is important, and especially children with DLD would need a substantial amount of it relative to their TD peers, so that they would not fall even further behind over time. Differences in benefiting from exposure in receptive mode might offer clinicians and kindergarten personnel an insight for evaluating challenges in bilingual development. Severe challenges in vocabulary development in the DLD group also call for both individually targeted small-group activities for learning words as well as strategies for strengthening vocabulary in various environments and everyday life situations. What this paper adds What is already known on the subject Language exposure is often found to explain more of the variation compared with AoO in early L2 vocabulary. On the other hand, it has been suggested by some researchers, but not all, that AoO effects would be found. Exposure and AoO might also interact differently depending on the task and whether the development is typical or disordered. Contrary to the clinical observation, diagnostic value of receptive vocabulary has often been questioned. What this paper adds to existing knowledge This study indicates that receptive vocabulary might be useful in differentiating bilingual TD and DLD. Language exposure effects differ between TD and DLD groups, but depending on task. Lower performance, but also slower cross-sectional development, is found in receptive vocabulary for children with DLD. Interaction between language exposure and AoO stresses the importance of taking both into consideration when studying bilingual development. What are the potential or actual clinical implications of this work? L2 vocabulary tests can be used in differentiating bilingual children with TD and DLD when exposure is taken into consideration. Difficulties using exposure and, hence, slower development in children with DLD suggest that especially receptive vocabulary might be diagnostic by the accumulating exposure. Investing in ways of supporting vocabulary development through small-group activities and in everyday situations of bilingual children at risk of DLD is highly recommended. This is important to prevent them from incrementally falling further behind their TD peers over time. A limited AoO effect suggests that families have more flexibility in terms of when to place their child in L2 immersion in their early years.
语言接触是影响发育正常（TD）儿童双语词汇发展的关键因素。然而，对于发育性语言障碍（DLD）儿童的接触效应，尤其是与第二语言习得的发病年龄（AoO）之间的相互作用，我们了解甚少。
在赫尔辛基纵向语言迟缓研究（HelSLI）中，我们调查了TD和DLD的顺序双语儿童的接受性和表达性第二语言（L2）词汇表现以及横断面词汇发展情况，以确定这两组儿童是否可以根据其词汇表现进行区分。更重要的是，我们研究了AoO和语言接触对这两组双语儿童词汇表现的影响。
我们招募了70名来自医院门诊的DLD儿童和82名来自幼儿园的TD儿童。这些儿童年龄在3至7岁之间，L2的AoO不同，语言接触程度也各不相同。在考虑AoO和语言接触影响的情况下，使用多元回归分析在两项接受性词汇测试和三项表达性词汇测试中对两组儿童进行比较。
在接受性和表达性词汇测试中，TD儿童的表现均优于DLD儿童。语言接触可预测词汇，但AoO则不然。在接受性词汇方面，TD组和DLD组的语言接触效果不同，但在表达性词汇方面则没有差异。此外，在接受性词汇方面发现了语言接触和AoO的相互作用，两组情况相似。随着语言接触的增加，与表达性词汇相比，两组在接受性词汇方面的表现差异变得更加明显。
在考虑语言接触的情况下，TD和DLD的双语儿童可以通过L2词汇测试进行区分。3至7岁儿童的AoO效应不显著，这表明在开始L2沉浸式学习的时间上具有灵活性。然而，语言接触很重要，尤其是DLD儿童相对于TD同龄人需要大量的语言接触，这样他们才不会随着时间的推移而进一步落后。在接受模式下从语言接触中受益的差异可能为临床医生和幼儿园工作人员评估双语发展中的挑战提供见解。DLD组在词汇发展方面面临的严峻挑战也需要针对个体的小组单词学习活动以及在各种环境和日常生活情境中强化词汇的策略。
在早期L2词汇方面，通常发现语言接触比AoO能解释更多的变异性。另一方面，一些（但并非所有）研究人员认为会发现AoO效应。根据任务以及发展是典型还是紊乱，语言接触和AoO的相互作用方式也可能不同。与临床观察相反，接受性词汇的诊断价值常常受到质疑。
本研究表明，接受性词汇可能有助于区分双语TD和DLD儿童。TD组和DLD组的语言接触效果不同，但取决于任务。DLD儿童在接受性词汇方面表现较差，横断面发展也较慢。语言接触和AoO之间的相互作用强调了在研究双语发展时同时考虑这两个因素的重要性。
这项工作的潜在或实际临床意义是什么？
在考虑语言接触的情况下，L2词汇测试可用于区分双语TD和DLD儿童。DLD儿童在利用语言接触方面存在困难，因此发展较慢，这表明尤其是接受性词汇可能通过累积接触具有诊断价值。强烈建议通过小组活动以及在有DLD风险的双语儿童的日常情境中支持词汇发展的方式。这对于防止他们随着时间的推移逐渐落后于TD同龄人非常重要。有限的AoO效应表明，家庭在孩子早年何时开始L2沉浸式学习方面具有更大的灵活性。
