THE DEVELOPMENT OF MULTIMODAL SOCIAL COMMUNICATION IN INFANTS AT HIGH RISK FOR AUTISM SPECTRUM DISORDERS

In addition to impairments in gaze, facial expression, gesture, and sound, children with autism spectrum disorders (ASD) have difficulty producing these behaviors in coordination. Two studies were designed to evaluate the extent to which delayed and/or atypical development in the production or coordination of social communication behaviors can identify children eventually diagnosed with ASD. This research was grounded in Dynamic Systems Theory (DST), which proposes that changes in development depend on the interaction of multiple subsystems within the child, the environment, and the demands of the task; and that instability in one component can translate into varied developmental courses. A prospective longitudinal design was used to compare 9 infants at high familial risk for ASD (HR) later diagnosed with ASD, with 13 HR infants with language delay, 28 HR infants with no diagnosis, and 30 low risk (LR) infants. Participants were observed at home during naturalistic play with a primary caregiver at 8, 10, 12, 14, and 18 months. Frequencies of gestures, words, non-word vocalizations, eye contact, and smiles, and instances in which behaviors overlapped in time, were coded from videotape. Study 1 revealed that, while all infants demonstrated similar levels of communicative behavior at 8 months, ASD infants exhibited significantly slower growth in coordinations involving pre-speech vocalizations and those involving gestures used for joint attention than all other infants, even those exhibiting language delays. Study 2 demonstrated that information gathered on social communication skills during a natural setting improved prediction of diagnostic outcome when combined with standardized assessments and parent report; and the setting, method of measurement, and frequency of assessment were important factors in determining risk. Across both studies, variability was detected between and within infants. Results suggest that behavioral signs of ASD emerge over time in specific areas of communication. Disruption in the coordination of pre-speech vocalizations may result in negative cascading effects that have important implications for later social and linguistic development. Findings emphasize the importance of examining a wide range of communicative behavior in HR infants across contexts repeatedly over time and that DST offers a valuable framework with which to better understand their development