Abstract：Abstract: The concept of node word was introduced into the study of lexical semantic collocation and corpus linguistics by the Neo-Firthian school. Due to the influence of research methods and research perspectives, previous studies on node words only emphasized their data meaning in processing, and lacked sufficient researches on their motivation, processing and functions in second language vocabulary acquisition. Owing to these, the role of node words in lexical semantic processing has not been fully understood and valued. On the basis of Sinclair’s extended unit theory and the usage-based theory of lexical semantic processing, this paper has studied the node word and node effect in terms of motivations, features and functions. The findings show that a node word could be holistically processed at semantic level, and its activation can be represented by the degree of semantic access and node effect in local discourse. Node effect has positive correlation with lexical processing and lexical acquisition. The pivotal role of node word in collocation and semantic network construction is beneficial to develop learner’s vocabulary knowledge. It is suggested that the concept and functions of node word should be further studied in lexical semantic processing, and more attentions should be directed to the roles of node word and node effect in the process of second language vocabulary acquisition.
Key words: cognitive processing; node word; node effect; lexical acquisition
