While young infants appear competent in some task contexts, older toddlers often show difficulty with the same concepts. They apparently fail to understand something that infants are competent of. Such discrepancy in performance is puzzling, but only if task performance is taken to reflect knowledge or competency. The current study makes a different assumption: Namely that task performance reflects the immediate constraints of the task. We hypothesize that low performance in a conceptually easy task comes from a difficulty with spatially integrating relevant pieces of information. To test this hypothesis, we manipulated the degree of necessary spatial integration in a task that was originally taken to demonstrate toddlers difficulty with the concept of object solidity. Indeed, toddlers performed better when task constraints were present that minimized the degree to which spatial integration was required. The results point to an important problem in research that seeks to isolate a childs knowledge.