Humans form models of statistical regularities in sensory stimuli and make predictions from them. For example, participants expect regular patterns of auditory tones to continue, and generate phasic arousal and pupil dilation responses (PDRs) when such expectations are violated (Zhao et al., Nature Communications, 2019; Basgol, Cortex, 2024). In the current study, we conducted two experiments to examine whether these findings can be generalized to spatiotemporal visual patterns involving regular and random patterns of white dots appearing at different locations on a grid. In the first experiment (N=14), we used (a) transitions from a regular pattern to a random or another regular pattern (both violating the earlier regularity) or (b) transitions from a random to a regular pattern (realizing a new regularity). Participants were instructed to find blanks in patterns so they had to keep paying attention. In the second experiment (N=19), we used only regularity violations (condition (a)), and instructed participants to report if the white dot changed shape. We observed that violations, but not the emergence, of visual regularities evoked PDRs. Further analysis indicated that the dissimilarity between regularities before and after the transition was associated with their magnitudes.