Abstract
This multiple case study investigated the influence of extroversion and introversion in the acquisition of vocabulary in a second language. There were two child-subjects ages seven and eight who are extrovert and introvert, respectively. Their first language is Kalagan and they were exposed to Sinama through letting them involve directly in interactions in the language for twelve weeks; there was no teaching of vocabulary. Children’s utterances as well as their behavior were observed and documented using audio, video and/or anecdotal records. The naturalistic data taken from the recordings were the bases of analysis. The results show that the extrovert child was able to utilize more Sinama vocabularies in the course of interactions compared to the introvert child. However, he talked with less reflection making some words he uttered not appropriate in the context. On the other hand, the introvert child was able to comprehend more vocabularies compared to the extrovert child. Moreover, he carefully thought of the words to utter in conversation, making his words appropriate to the context. Thus, the results of the study suggest that these two psychological factors have a major influence on second language vocabulary acquisition processes, in which extroversion has positive influence on fluency, while introversion positively influences accuracy.
