Dependency network approach to the oral production of English- and Chinese-speaking healthy older adults

Linguistic research has increasingly focused on the language of older adults, although findings remain controversial on whether language skills decline with age. Additionally, extant studies only deal with certain aspects of language, such as lexis or syntax, and few have systematically investigated this topic. This paper assumed a holistic perspective and dependency network approach to explore healthy older adults' oral language at lexical, syntactic, and discourse levels. By constructing English and Chinese dependency treebanks, and corresponding dependency networks, of 100 healthy older adults and comparing them with those of all age groups, we found that 1) many parents appear before their dependents in the older adults' English treebank due to the massive use of articles before nouns; in the Chinese treebank, the reverse applies because of the large number of aspect markers; 2) the mean dependency distance (MDD) of English older treebank is longer than that of the all-age group. Furthermore, there are many compound and complex sentences in older adults' speech; the MDD of the Chinese treebank is shorter, while the syntactic structure conforms to grammatical rules; 3) the average degree ()s of both English and Chinese older adults' dependency networks are higher and clustering coefficient (C)s slightly lower, indicating strong connectivity of words in the two networks and coherence in participants' speech. In conclusion, there was no significant deterioration in the oral language of healthy older adults, although cross-language comparisons show very fine, detailed, and revealing differences between English and Chinese treebanks and networks.