Question on “mind” has been a confusing yet fascinating topic to linguists and psychologists for several decades. Some psychologist put forward a Modular Theory that the human mind consists of two distinct parts --- peripheral modules (input and output modules) and central cognition. However, others believe that the mind is almost entirely modular. Anyway, the mind may be modular with many specific modules --- modules of five senses, modules of language, central modules and so on.
Among them, central modules are powerful in taking input and generating output but language modules can be caught up in both input and output processes. Thus interaction between modules or in particular between language modules can facilitate other module to produce certain action or language.
Language modules are actually composed of lexical, syntactic, semantic, and pragmatic sub-modules etc. In speech, semantic module may render central cognition part of or the whole idea whereas syntactic module may integrate the idea into a few complete and grammatical sentences. In classroom activities, syntactic module interacts with semantic module with the help of other modules. These two modules come to be prominent since they occupy most part of the mind while thinking. That’s why these two modules are often considered in studies, which can help produce good effect of language teaching and learning. So mysterious is the working mechanism of the modules that it deserves inflecting, discussing and studying. Therefore, this issue aims to draw readers’ attention and interest in the effect of the classic theory on language teaching and learning. There are still many relative questions to deal with. How do central modules work with peripheral modules? How do language modules function in thinking, speaking, and learning? What modules may get involved in language production? In what way can instructors help learners memorize words and expressions? Can syntactic module hinder the processes of such difficult grammar as unreal conditions and relative clauses in English? Can semantic module work well without any participation of syntactic module? Is modularized knowledge conducive to learning a second language? How do language learners establish a good habit of speaking in a second language? If confused by these questions, come to focus on them. And any attempt to solve them is desirable.