Selected studies of infant development concern biological rhythms, pattern preferences, sucking, and Negro-white comparisons. Sex, age, state, eye to eye contact, and human symbiosis are considered in mother-infant interaction. Included in pediatrics are child development and the relationship between pediatrics and psychiatry. Environmental influences on learning which are discussed are optimal environment, parental influence, and teacher appraisal; learning disturbances include reading disability and stimulus competition. Learning patterns and violence in disadvantaged children are described; and familial mental retardation, social class and mental illness, psychopathology, obstetric complications, and behavior problems are discussed. Also mentioned are depression, behavior therapy, emotional reactions, cryptorchism, home visits, social class and mental illness, a followup study of infantile psychosis, schizophrenic twins, perceptual and motor discrimination in psychotic and normal children, and psychosis of childhood. Neglected and abused children are also considered. (RP)