<p>This study introduces the Epistemic Integration Matrix (EIM) as a design-oriented framework linking theorized short-term epistemic triggers (doubt and emotion) with longer-term belief development to examine how students engage in socioscientific issue (SSI) web searches. Participants were 146 Taiwanese sixth graders who completed structured searches in which informational positions (positive, negative, conflicting) were systematically manipulated. Behavioral traces—breadth (pages viewed), depth (time on task), and immersion (dwell time per page)—were collected as indicators of volitional engagement. Linear mixed-effect models showed that negative and conflicting framings broadened exploration, with conflict further deepening sustained attention, whereas immersion effects were weak. Moderation analyses highlighted justification and knowing as decisive factors: students with more sophisticated epistemic beliefs sustained longer engagement under negative framing, while less-developed peers showed flat responses. Development and knowledge also reached significance but less consistently. These findings suggest that selected epistemic dimensions shape patterns of volitional persistence, supporting the EIM as a useful explanatory lens and a design scaffold for SSI inquiry platforms in elementary education.</p>