Abstract: Most languages of the world have a high proportion of morphologically complex words that are composed of two or more morphemes. When processing morphologically complex words, readers can choose to access the whole word meaning directly from the mental lexicon, or to use morphological rules to construct the word semantics. There is a general consensus that native speakers can access the whole word meaning by combing morphemes, however, despite increasing amount of second language research, the morphologically complex word processing mechanism for L2 learners is still in debate. Based on Complementary Learning Systems account and Episodic L2 Hypothesis, the processing mechanism of L2 morphologically complex words is proposed. Future research needs to explore the influences of morphological family size on the processing of L2 morphologically complex words, as well as reveal the neural mechanism underlying L2 morphologically complex words.

Key words: second language learner, morphologically complex words, processing mechanism, morphological rule