Singletary Britt, Jiang Hui, Wilberforce Winifred Graham, Avelar Daniela, Strother-Garcia Kristina, Justice Laura M
Crane Center for Early Childhood Research & Policy, The Ohio State University, Columbus, Ohio, USA.
Infancy. 2025 Jul-Aug;30(4):e70036. doi: 10.1111/infa.70036.
Studies show children in low-income households have heightened risk of developing as late talkers (LTs). Scholars have attributed the cause of these differences to variability in child-directed and observed language input, parenting quality, attendance at childcare facilities, or some combination therein, as briefly reviewed. However, this study focuses on a sample entirely of families experiencing low income to explore differences within this group. This study explores growth trajectories for child vocabulary production from age 8-30 months in a racially-diverse low-income longitudinal sample in the U.S. (n = 199). Using multi-level multiple group models, we explore differences in growth trajectories for LTs and non-LT peers (identified: age 22-30 months) and identify the age at which vocabulary sizes begin to significantly differ, controlling for the effects of child age-at-test, sex, primary home language, and mother's education. Results show distinctly different trajectories, such that: (1) LTs experience relatively flat growth resulting in significantly smaller vocabulary sizes over time and (2) divergence occurs at ∼11 months. Future research is needed to fully understand how and why LT trajectories begin to differ so significantly at this age, and how we can better intervene earlier to reduce the likelihood of LT.
研究表明，低收入家庭的儿童发展为晚说话者（LTs）的风险更高。学者们已将这些差异的原因归结为儿童主导和观察到的语言输入、养育质量、在儿童保育机构的出勤率或其中的某种组合差异，简要回顾如下。然而，本研究关注的样本完全是低收入家庭，以探究该群体内部的差异。本研究在美国一个种族多样的低收入纵向样本（n = 199）中，探索了8至30个月大儿童词汇产出的增长轨迹。使用多层次多组模型，我们探究了晚说话者与非晚说话者同龄人（确定年龄为22至30个月）的增长轨迹差异，并确定了词汇量开始出现显著差异的年龄，同时控制了儿童测试时的年龄、性别、主要家庭语言和母亲教育程度的影响。结果显示出明显不同的轨迹，即：（1）晚说话者经历相对平稳的增长，随着时间推移词汇量显著较小；（2）差异在大约11个月时出现。需要未来的研究来充分理解晚说话者轨迹在这个年龄开始出现如此显著差异的方式和原因，以及我们如何能够更好地在早期进行干预以降低成为晚说话者的可能性。
