and less commonly, motility, sensory modulation, and attention. One video study found that a combination of nineteen social and sensory items differentiated children (6-48 months) with autism from those with mental retardation as well as those with typical development. However, few of the autistic sebjects were under two years of age, which provided limited information on the usefulness of some of the items during the infancy period. The purposes of this study were to (a) explore the usefulness of sensory-motor variables in addition to social markers of autism during the infancy period; (b) identify variables that may indicate differences at nine to twelve months of age-earlier than previously accomplished using retrospective video analysis; and (c) discriminate between groups of children with autism, developmental disabilities, and typical development with respect to these variables (Loesche, 1990).Studying the pattern of intact abilities and impairments shown by infants with autism in the early emerging social-communicative abilities should tell us which behaviors are functionally related to the later emerging skills, which previous research has demonstrated are impaired in school-age children with autism. This type of study will have implications for our understanding of the abnormal development of social communication in autism and will further our understanding of the developmental trajectories of empathy, play, joint attention, and imitation in the normal case. Indeed, it is apparent that in many of these areas-such as the relationship between functional and pretend play or the relationship between basic level imitation and more complex imitation-there are significant gaps in our understanding of normal development (Ehlers and Gillberg, 1998)....
