This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Autism Spectrum Disorder (ASD) is estimated to affect approximately 1 out of every 166 children around the world, with a prevalence rate that makes it the most common developmental disability. Conservative estimates report that in the US over 400,000 people have some forms of ASD. The symptoms start to appear early in life and result in a lifelong disability with no cure at present. However, significant improvements occur with early intervention and there is some degree of success at returning to normality upon very early intensive behavioral treatment. Common to all the children with ASD are deficits in social responsiveness and communication. Notably, none of these children can properly interact with and function in their world. They cannot engage in imaginative, make-believe play and fail to initiate and sustain conversations with other children. The causes are unknown but growing evidence suggests that abnormal brain development influenced by their environment is in great part responsible for the symptoms. At present there are no non-invasive techniques to measure their behaviors, eye motions and facial expressions. There are no objective indexes of performance in the current screening batteries that can be used for diagnosis, therapy and to longitudinally track their progress. There are no classifications of ASD individuals into subgroups according to sensory motor deficits manifested in natural intentional motions of every day life tasks. This project will provide a set of non-intrusive data-capture techniques and a theoretical framework to define, simulate and empirically quantify key aspects of the social interaction problem. The research will use a geometric characterization of sensory-motor integration to investigate the roles of reference frames in steering the system to the most adequate source of sensory input in a given situation. The basic idea underlying the formal theoretical formulation is that the ASD system is impaired at forming sensory maps so it cannot intentionally switch perspectives between internally- and externally- based sources of sensory input; it cannot align sensory maps with information regarding disparate sensory processing times and generally it cannot integrate sensory processing delays from different internal-external modalities with additional sensory motor feedback delays. As a consequence the ASD system cannot have proper body awareness; lacks the ability to cast the same scenario from different perspectives; lacks the ability to decouple the physical reality from the mental representation of it, the ability to abstract; and can mostly react but not predict or anticipate its own actions, let alone the actions or the intentions of others. The theory generates a number of concrete testable predictions that will be addressed in a collaborative effort between Psychology and Computer Science at Rutgers University. A set of psychophysical experiments evaluating the different hypotheses will be carried on in children with ASD and in normally developing peers from the University's Douglass Developmental Disability Center. The research will assess several objective indexes of performance during intentional acts embedded in every day life activities and will manipulate the sources of sensory guidance to assess potential improvements in performance each day. Since such geometric indexes are independent of the movement dynamics, and of the degree of novelty or automaticity at performing the task, it is possible to address natural, unconstrained voluntary behavior and objectively quantify how the various hypothesized critical ingredients for normal social interaction break down in ASD. Even if the novel hypotheses fail, the research will be instrumental in (1) developing and standardizing non-invasive recording techniques for other Developmental Disabilities researchers to use; (2) assessing a number of currently unexplored questions and (3) providing new experimental paradigms to systematically study these problems in the ASD population. This research project will contribute to significantly advance our understanding of general brain mechanisms to control behavior, to interact with and to communicate in social environments. The project will cross over multiple fields including Clinical and Developmental Psychology, Special Education, Occupational Therapy, Computer Science and Applied Mathematics to tackle a problem of epidemic proportions according to the CDC. The measurements taken in this study will be properly scaled to young infants in order to create an objective diagnosis tool that will help society start intensive behavioral treatment before three years of age. This is important because of the high incidence and prevalence of ASD and the lack of objective screening measures for early detection and intervention. Furthermore, this project will cluster ASD children according to the areas of sensory motor deficits, superior perceptual capabilities and learning capacity within different school-age groups. This will provide a more complete picture of the phenomena with new insights into its longitudinal evolution in the developing human brain.