The effectiveness of online discussions depends on how learners interact with each other. Instructors should provide adaptive supports to learners with difficulty in sharing their opinions and questions with others. Social network analysis can provide insights into the dynamics of interactions in online discussions. This study explored how learners' achievement goals affect learners’ centrality in a social network. For this study, 107 undergraduates enrolled at a university in South Korea participated in the online discussion over a week. This study found that achievement goals influenced the time of first writing and the types of online discussion messages, which were grouped into active participation, critique-oriented, and idea-oriented clusters. Although achievement goals did not significantly influence in-degree centrality, the time of first writing and the message types had significant effects on it. For out degree centrality, mastery approach goals and the message types had significant effects. Learners of the active participation cluster showed higher in-degree and out-degree centrality than the others. This study implies that instructors should help learners experience more meaningful interactions in online discussions by enhancing mastery approach goals and providing scaffoldings for early participation and diverse types of messages.

Keywords : Online discussion, Achievement goals, Social network analysis, Centrality