Understanding the regularities in the learning environment, how they differ among individuals, and how individuals through their own behaviors create those differences are essential to understanding typical and atypical courses of development, to developing remediation and intervention procedures. The proposed research develops a new method to study the dynamic visual environment of infants and toddlers, from the first-person view. Progress has been limited by several technical problems including: (1) recording devices that will be tolerated by young children and (2) the number of independent degrees of freedom in eye, head, and body movements. We believe we can solve these technical problems. The research has three specific aims within the goal of studying active vision in children 10 to 36 months of age: (1) to develop a system through which one can measure the dynamic first-person visual field (via a small camera on the head of the child), the direction of eye gaze in that field (via additional cameras and software that track eye position), and also head, hand and body movements (via position sensors placed on the head, shoulders and hands); (2) to determine the spatial and temporal resolution of the head-camera image relative to the child's perceptual field; (3) to demonstrate the utility and functionality of the system in two different task contexts - mother-infant toy play at a table and free play with ambulatory movements. This new method promises fundamental new insights about the learning environment and the development of dynamic visual processes in the context of a 3-dimensional physical and social world, the context in which children build social, language and cognitive skills. The proposed new method has significant biomedical relevance for the early detection of attentional disorders, for studying their cascading consequences in social, cognitive and linguistic development, and for developing new therapies and interventions that generalize to the complex natural environment [unreadable] [unreadable] [unreadable]