Abstract: Examined capacities for spatial reorientation in humans. In a series of experiments, young children (aged 18.1-24.1 mo) who were disoriented in a novel environment reoriented themselves in accord with the large-scale shape of the environment but not in accord with nongeometric properties of the environment such as the color of a wall, the patterning on a box, or the categorical identity of an object. Because children's failure to reorient by nongeometric information cannot be attributed to limits on their ability to detect, remember, or use that information for other purposes, this failure suggested that children's reorientation, at least in relatively novel environments, depended on a mechanism that is informationally encapsulated and task-specific: 2 hallmarks of modular cognitive processes. Parallel studies with rats suggest that children share this mechanism with at least some adult nonhuman mammals. In contrast, our own studies of human adults (aged 17-26 yrs), who readily solved our tasks by conjoining nongeometric and geometric information, indicated that the most striking limitations of this mechanism are overcome during human development.