Project Summary Infants’ early motor experiences (e.g., grasping, crawling, walking) are consistently related to later achievements and abilities, including their ability to understand and learn from others and even their language development. However, the mechanisms by which early motor experience is related to later achievements are not fully understood. Parents’ perceptions of their child’s mental and cognitive abilities increase with the child’s development. Witnessing the increased capability of their child’s engagement with the environment may result in increased perception of their child as capable of more advanced thinking, planning, and acting. This proposed shift in perception could then impact their interactions with their child. In fact, mothers who attribute greater mental abilities to their infants tend to exhibit more sensitive parenting behavior, and parents provide differential input depending on their child’s motor skills. Thus, the link between early motor experiences and subsequent development may be, in part, explained by changes in parents’ perceptions of and interactions with their child. In the proposed project we will examine how parents’ perceptions are related to their parenting behavior, and the potential for parents’ perceptions of their children to mediate the association between infants’ early motor experiences and subsequent development. In Study 1, we will first explore whether a training paradigm that provides infants with specific motor experiences outside of their current repertoire, and that has been shown to increase infants’ motor skill (i.e., reaching and object exploration), also impacts parents’ perceptions about their child. We expect that changes in infants’ motor skills will be related to changes in parents’ perceptions, and that individual differences in parents’ perceptions will mediate the relation between early motor experiences and later skills. In Study 2, we will manipulate parents’ perceptions of their child – inducing a perspective that either over estimates or under estimates their child’s current capacity for understanding their own and others’ thoughts, emotions, and agency – and we will then examine the relation between these different perceptions of their child and their behavior in interactions with their child. We expect that those parents induced to over-estimate their child’s ability will show more sensitive and stimulating behavior as compared to those induced to under-estimate their child’s ability. This project has the potential to advance our understanding of a foundational developmental cascade, to provide insight into how parent–child transactional processes support development, and to inform targeted interventions for infants and families whom might benefit from additional support.