Theory of distributed cognition unveils the answer to what constitute distributed cognition. However, how the distributed cognition in web-based learning environment spreads out still remains a black box. This study sought to deepen our understanding on how learners' knowledge disseminates online by examining the impacts of three kinds of communication, namely intra-action, interaction, and outeraction. This paper conducted a quasi-experimental study and invited 135 Taiwanese college students to help us explore our attempted research question. The results clearly demonstrated that intra-action has stronger relationship with learning outcomes than interaction or outeraction. In addition, considerable correlation was detected between intra-action and interaction. Subsequent interviews with learners indicated that considerable part of the positive relationship between intra-action and learning achievement may be due to cause-effect, namely, intra-action activities are perceived by learners as contributing to positive learning outcomes. In sum, this study contributes to the literature because (a) we extend previous research on distributed cognition by examining the impacts of three kinds of communication; (b) we suggest it is worthwhile for researchers to further study the impact of intra-action; (c) by distinguishing the three communications, we introduce one way that can measure status of the constituent elements of distributed cognition that exists in a distance learning environment. (Contains 6 tables and 5 figures.)