本研究采用交叉聚合设计,从词汇量角度考察了两岁左右汉语婴儿是否存在＂名词优势＂现象。在前测中,110名18、24和30个月龄的儿童接受了PCDI量表和父母问卷调查;6个月后,18个月和24个月组接受了PCDI量表的再测。本研究将＂名词优势效应＂定义为＂（名词得分-动词得分）/词汇总分＂（以k值表示）,将名词得分大于动词得分者定义为＂名词优势者＂。结果发现：（1）从各年龄组均值来看,18个月组名词优势效应较小（k=.07）,24及30个月组名词优势效应显著增大（k=.11~.19）。（2）从个体水平来看,18个月组名词优势者和动词优势者约各占50%（p〉.05）,而24、30个月组中81~100%的儿童都是名词优势者。该结果提示,以往不同研究之间的分歧可能是由于名词优势是随年龄而动态变化的。

Most previous studies found that nouns were acquired predominantly by infants in many languages, thus the noun bias was considered to be universal in children’s early vocabulary acquisition. On the contrary, verbs were more difficult for children to learn, as they were less concrete and more relational than nouns. However, whether Mandarin Chinese is a verb-friendly language for children or not is still in hot debate. Evidences from natural observations and laboratory investigations were controversial. Researches that used vocabulary checklist found that Mandarin-speaking infants learnt many more verbs than their English-speaking peers did（Tardif, 1996）. In the meanwhile, some experimental studies found that Chinese children met more difficulties in verb learning tasks than English and Japanese children did even in preschool years（Imai, et al., 2008）. To further explore the noun / verb bias issue in Mandarin-speaking infants, it is proposed that the ratio of nouns and verbs should be carefully examined in the present study, as the ratio of nouns and verbs might vary with children’s age.In this study, the Mandarin-speaking infants’ expressive vocabulary size was examined to explore the ratio of nouns and verbs in a 6-month longitudinal study. In the first investigation, a sample of 110 infants were divided into three age groups, 18-, 24- and 30-month olds. All infants were tested using PCDI（Chinese Communicative Development Inventory- Putonghua Version） and a self-designed questionnaire for parents. The 18- and 24- month olds were re-tested after 6 months using PCDI. In the present study, the Noun Bias Effect was defined as ＂（noun vocabulary size- verb vocabulary size）/whole vocabulary size＂, the result of this calculation was labeled as k. The results indicated that the noun bias effect was small in the 18-month old group（k =.07）, but it soon enlarged in the 24- and 30- month olds（k =.11~.19）. At the individual level, we defined the Noun Bias Infants as infants that learned more nouns than verbs. The results showed that the noun bias infants and the verb bias infants each constituted 50% of the whole in the 18-month old group（p 〉.05）. However, with the increase of age, most（81~100%） of the infants in the 24- and 30- month old groups showed noun bias. In summary, the results in the present study indicated that the noun bias effect increased with age in Mandarin-speaking infants. Verb bias infants were more likely to be found in infants who were less than 18-month old, and noun bias infants were more predominant in children of 24- month old or older. It was suggested that previous divergence in the noun / verb bias among Mandarin-speaking infants might result from the change of noun bias itself. Future studies may focus more on how and why noun bias changes with age in early word learners.