Thorpe Karen, Rutter Michael, Greenwood Rosemary
School of Early Childhood, Queensland University of Technology, Brisbane, Australia.
J Child Psychol Psychiatry. 2003 Mar;44(3):342-55. doi: 10.1111/1469-7610.00126.
Twins tend to lag behind singletons in their language development, but the causes were unknown.
Ninety-six twin pairs from the Avon Longitudinal Study of Parents and Children (ALSPAC), for whom birth was after at least 33 weeks of gestation, were compared with 98 pairs of singletons, no more than 30 months apart in age. Parental qualities and family interaction were assessed through standardised questionnaires and interviews and both structured and unstructured observations in the home at 20 months and 36 months. The possible causal role of postnatal family influences was assessed through five criteria: i) the feature had to differ between twins and singletons; ii) individual differences in that feature had to relate to individual differences in language level within the sample of singletons and of twins; iii) the feature as measured at 20 months had to predict language as assessed at 36 months; iv) that had to apply after controlling for language level at 20 months; and v) introduction of the predictive feature into an overall model had to obliterate the twin-singleton difference in language level.
Patterns of parent-child interaction and communication met these five criteria. The maternal factors all concerned aspects of interaction that were broadly concerned with communication: encouraging the child to speak, providing elaborating comments, engaging in reading to the child and talking about the story and its illustrations. The HOME inventory findings provided similar findings with respect to responsiveness, involvement and level of experiences involved. Family features that might have been influential, but which were not, included parental depression, breast-feeding, family size, and style of sibling interaction.
Patterns of parent-child interaction and communication within the normal range have environmentally mediated effects on language and account for twin-singleton differences in language developmently. The results indicate the value of a natural experiment in testing competing causal hypotheses, and show the role of environmental factors as influences on language variations within the normal range, for both twins and singletons.
双胞胎在语言发展方面往往落后于单胎婴儿，但其原因尚不清楚。
将来自雅芳亲子纵向研究（ALSPAC）的96对双胞胎（其出生时孕周至少为33周）与98对单胎婴儿进行比较，这些单胎婴儿的年龄相差不超过30个月。通过标准化问卷和访谈以及在孩子20个月和36个月大时在其家中进行的结构化和非结构化观察来评估父母素质和家庭互动情况。通过五个标准评估产后家庭影响可能的因果作用：i）该特征在双胞胎和单胎婴儿之间必须存在差异；ii）该特征的个体差异必须与单胎婴儿和双胞胎样本中的语言水平个体差异相关；iii）20个月时测量的该特征必须能够预测36个月时评估的语言能力；iv）在控制20个月时的语言水平后这一点仍须成立；v）将预测特征引入总体模型必须消除双胞胎和单胎婴儿在语言水平上的差异。
亲子互动和交流模式符合这五个标准。母亲因素均涉及与交流广泛相关的互动方面：鼓励孩子说话、提供详细评论、给孩子读书并谈论故事及其插图。家庭观察量表（HOME）的调查结果在反应性、参与度和所涉及的体验水平方面提供了类似的结果。可能有影响但实际上没有影响的家庭特征包括父母抑郁、母乳喂养、家庭规模和兄弟姐妹互动方式。
正常范围内的亲子互动和交流模式对语言具有环境介导作用，并解释了双胞胎和单胎婴儿在语言发展上的差异。结果表明了自然实验在检验相互竞争的因果假设方面的价值，并显示了环境因素对双胞胎和单胎婴儿在正常范围内语言差异的影响作用。
