Infants build expectations about repeated stimuli and show signs of surprise when their expectations are violated. This talk presents evidence from two studies investigating infants’ pupil dilation responses (PDR) during expectation violation in categorical versus non-categorical learning contexts. PDR to deviating trials should be related to the conceptual (or spatial) distance to the expectation. In Study 1 (N = 45, age = 14 months), infants learned about either individual objects or object categories—a form of learning linked to early language development. During test trials, infants viewed novel objects that were either from the same or a different category. PDRs revealed that infants showed stronger dilation to different-category test events than to standard control events, but not to same-category test events, and only after category learning—not after object learning—indicating category-based expectations and surprise (cluster-mass t = 902.90, Monte Carlo p = .004). In Study 2, infants repeatedly saw a stimulus appear at a location before it reappeared at the same, a deviating 90°, or 180° location. In the first two Experiments (N = 53 and N = 50), infants did not show significant PDR differences across test locations. In an additional Experiment investigating the categorical counterpart, infants learned about distributions of locations (data collection is ongoing, N ≈ 48). Together, these studies suggest that infants’ surprise responses—indexed by pupil dilation—depend on the type of regularity learned. Implications for different expectation violation dynamics between categorical and non-categorial contexts in infancy will be discussed.