The high rate of associated psychiatric symptoms (e.g., anxiety) in autism is a growing focus of interest and concern. It is unclear whether such symptoms exist as part of the core disorder of autism itself or as separate, co-morbid psychiatric conditions. Disentangling the source of such symptoms will have a tremendous impact on our understanding of autism, especially as it relates to treatment strategies. Psychophysiology methods that provide a non-verbal means of measuring psychiatric symptoms can reveal correlates of social, cognitive, and emotional processes in autism. These methods include event-related potentials (ERPs), electroencephalography (EEG), eye-tracking, galvanic skin response, and fear potentiated startle response. Dr. Murias' fellow will use these techniques to test whether anxiety-related symptoms in autism are associated with atypical physiological responses. These responses will be compared across four groups of adolescents: those with autism and anxiety, those with autism without anxiety, those that are typically-developing but with anxiety, and those that are typically-developing without anxiety. The study will also examine individual differences in anxiety severity to see if they correlate with individual differences in these psychophysiological responses. This design will allow the detection of anxiety-related signals, and determine if they are shared between autistic and typically-developing subjects. What this means for people with autism: These results will distinguish whether anxiety is a core autism symptom or a coexisting psychiatric condition, which will inform pharmaceutical and behavioral treatment strategies for autism.