Understanding the relationship between seeing and knowing is fundamental to social cognition. While research demonstrates that even infants grasp basic aspects of this relationship, prior work often treats perceptual access and knowledge as equivalent (e.g., "if you see it, you know it"). In reality, their connection is richer: more complex objects require longer to encode, and agents’ looking patterns often reveal how well they have encoded something and how much they want it. Across three experiments, we investigated whether children understand these nuances. In Experiment 1, we found that by age six, children expect more objects to require longer looking times. In Experiment 2, children inferred that agents who looked longer were more likely to form accurate representations of what they observed. In Experiment 3, children reasoned that agents who looked longer at an object were more likely to want it. Together, these findings suggest that by age six, children develop an intuitive theory of attention, enabling them to make sophisticated inferences about others' mental states based on looking behaviors.