Longitudinal studies of mother-child interactions for the third trimester of pregnancy to age 4 are described. The effort is aimed at analyzing early childhood data to determine stability of mother-infant interaction, correlations among mothers' character as defined by adaptive and maladaptive defenses, major conflicts, sense of reality, and capacity for empathy with her external behavior with her baby; and correlations of the patterns of mother-infant behavior with the child's own emerging behavior. Analysis of films identified two time periods (9 months and 14 months) during which hand and finger mannerisms appeared in stress situations. Results are compared to an earlier study in which autistic Ss developed hand and finger mannerisms as a clear and persistent symptom between 9-12 months of age. A review of the major indicators of psychological differentiation suggests that the same period in which finger mannerisms reappear may mark the demarcation of autistic from normal development. Analysis of the specific context in which the stereotypies occur is further analyzed, and questions relating the mannerisms to such conditions as schizophrenic regression and Tourette Syndrome are raised. (CL)