This study aimed to investigate the dynamic patterns of two concepts of silence explicated as a communication strategy and impediment in a task-based instruction. A novel approach, Retrodictive Qualitative Modeling (RQM) tied in a Dynamic System Theory (DST), was utilized to identify learners' archetypes, to highlight the dynamic patterns underlying their silence, and to unveil the factors affecting the two concepts as dynamic signatures. Of eighteen learners of English department, we took three participants relying on their salient archetypes. Those participants were nominated based on the Focus Group Discussion (FGD) encompassing three lecturers. Furthermore, a stimulated recall interview was carried out on the three participants to get overarching factors affecting their silence. The results revealed twofold: (1) the participants' dynamic patterns of classroom trajectory explicating the variability of elements underlying the learners' silence vary across the learners' archetypes, (2) signature dynamics modeled manifest and distinguish the two concepts of silence. The implication of this study entails the EFL lecturers to have a background knowledge in distinguishing the two concepts of silence that encompass dynamic and fluctuative signature dynamics of motivation, cognition, English proficiency, positive and negative emotions interacting with the classroom contexts. Likewise, further study might provide more overarching factors underlying those two concepts of silence to provide a finer-grained result delineating such concepts.