<p>From the preverbal period, infants can distinguish different informants in social interactions and adjust their engagement accordingly. Yet little is known about whether these informant-based adaptations take shape during infants’ initial knowledge acquisition, before their manifestation in behaviours. To address this question, we conducted two gaze-contingent experiments to examine how infants organize their learning process according to the identities of informants in social interactions. In each experiment, infants were randomly assigned to learn two kinds of knowledge (e.g., Experiment 1: shape of “Chimo” and shape of “Wasa”; Experiment 2: shape of “Chimo” and color of “Heku”) either from different informants or from the same informant. Infants’ attention to the informant and pupil dilation patterns provided evidence that they could not only distinguish between different informants but also recognize the change in the learning contents. Based on these cognitive sensitivities, the infants’ gaze-selection results showed that their learning outcomes varied significantly depending on whether the same or different informants. These findings provide new insights into infants’ adaptive engagement in social interaction by demonstrating how they dynamically organize their learning processes in identifying the informants.</p>