In this case study, the language and cognitive development of a 4-year 5-month old profoundly deaf girl and her normally hearing identical twin sister were investigated by videotaping the twins in their home interacting with each other, the investigator, and family members. Materials used with the children were designed to elicit spontaneous,…

Stability of child and mother characteristics and the predictability of children's cognitive competence and affective characteristics were investigated as part of a longitudinal study. At 2 years of age, 46 sets of male twins and their parents were observed in the home and were rated for attachment, independence, compliance and conscience on the…

This paper describes a study which examined the performance of 48 pairs of 18-month-old twins on the Mental Development Scale of the Bayley Scales of Infant Development to determine whether score differences would be found for the three subgroups of identical, fraternal same-sexed, and fraternal opposite-sexed twins. Of the 96 subjects, 46 (23…