In this study, Dr. Belmonte and colleagues will test the hypothesis that the range of symptoms seen in autism can be explained by abnormally strong short-range connections within brain regions, and abnormally weak long-range connections between brain regions. These researchers hypothesize that social and communicative deficits seen in autism are due to weakening of the long-range connections between brain regions, which are necessary to coordinate the activities of these regions. This study will use electroencephalography (EEG) to measure brain activity in autistic children and their siblings, as well as a control group of normal children. Brain activity will be measured both within and between brain regions while the subjects play video games with embedded tests for both high-level and low-level functions, such as attention, executive function, perception, and social cognition. Computational analysis of the activity measured will allow researchers to determine the relative strength of neural connections in different subjects while performing different types of tasks. This research will evaluate a unified hypothesis of brain dysfunction in autism, which may lead to a better understanding of the neural pathways underlying the symptoms of autism.