This study investigates patterns of topical migration, specifically interactional dynamics of conceptual drifting and metacognition as counteracting forces, in interactive information retrieval. “Think aloud” sessions of exploratory search conducted by five graduate students were recorded, and the audio recordings were first coded into semi- structured notes and then converted into flow graphs for temporal analysis. The study finds that conceptual drifting, driven by the searcher's attempts to find more relevant results, unfolds as sequences of conceptual switching instances, with each sequence centering on a major concept (a focal point). As the search flow moves from one focal point to the next, it forms second-order patterns of conceptual drifting. Awareness of conceptual drifting typically occurs right after the changing of focal point, followed by metacognitive efforts of referencing the original search question or repeating the initial search. Metacognitive behaviors are found to be closely correlated to occurrences of conceptual switching. As more instances of conceptual switching occur, the searcher grows more likely to become aware of the shifting of focus and exercise mental efforts to regain control of the search process.