This research investigated the impact of the number of talkers with whom children engage in daily conversation on their language development. Two surveys were conducted in 2020, targeting two-year-olds growing up in Japanese monolingual families. Caregivers reported the number of talkers in three age groups and children’s productive vocabulary via questionnaires. The results demonstrated significant effects of variability in talkers in fifth grade or above in Study 1 (N = 50; male = 23; r = .372) and in adult talkers in Study 2 (N = 175; non-nursery going; male = 76; r = .184) on children’s vocabulary development, after controlling for language exposure time and demographic variables. Possible mediating factors are discussed. This research extends previous findings from immigrant bilingual children to monolingual speakers in Japan, suggesting the potential contribution of available talkers other than caregivers in conversational environments.

中文翻译：

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说话者的变异性对两岁儿童语言发展的影响

这项研究调查了与孩子进行日常对话的谈话者数量对其语言发展的影响。2020 年进行了两项调查，针对的是在日语单语家庭中长大的两岁儿童。护理人员通过问卷调查报告了三个年龄段的说话者数量以及儿童的有效词汇量。研究 1 的结果表明，五年级或以上的谈话者的变异性具有显着影响（氮= 50；男 = 23；r= .372) 以及研究 2 中的成人说话者 (氮= 175；非托儿所；男 = 76；r= .184) 在控制语言接触时间和人口统计变量后对儿童词汇发展的影响。讨论了可能的中介因素。这项研究将之前的研究结果从移民双语儿童扩展到日本的单语使用者，表明在对话环境中除了看护者之外的可用谈话者的潜在贡献。