The specific aims of the project are (1) to determine the types of impairments of emotional expression and perception that are found in autism, and (2) to investigate the neuropsychological bases of these impairments. Measures will be taken on three groups of subjects: autistic children ranging from 6 to 18 years of age, and developmentally-matched normal and mentally retarded children. These three groups will be compared in terms of their ability to perceptually discriminate and categorize facial expressions, and in terms of their spontaneous expression of various emotions. Measures of spontaneous emotional behavior will be taken in both a controlled laboratory setting and in naturalistic school situations. Parents will also provide information about their child's emotional behavior in a questionnaire The above measures will be used to investigate whether individual differences in affective and social ability are related to specific patterns of frontal and parietal lobe functioning. Electroencephalographic (EEG) recordings of right and left frontal and parietal activity will be taken in response to a variety of affective and cognitive stimuli. EEG will be subjected to power spectrum analysis to yield measures of alpha band power frequency (8-13 Hz). Measures of right and left parietal and frontal integrated alpha will be used to infer differential cortical activation during affective and cognitive processing. Comparisons of patterns of brain activity will be made among autistic, and matched mentally retarded and normal subjects. Specific predictions regarding the pattern of brain dysfunction expected in autistic subjects are based on current neuropsychological models of emotion. The long term objectives of the research program are to shed light on the neuropsychological bases of early infantile autism and to use this information to develop more effective diagnostic and treatment methods for autistic persons.