Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


This study was a comprehensive descriptive comparison of the early social behavior of twins and singletons in a playgroup situation. Eight pairs of same-sex female twins and 16 age-matched female singleton children, ages 17 to 43 months, participated as subjects. Playgroups composed of one pair of twins and two same-age unfamiliar singletons met for two free play sessions with their mothers present. A wide range of observational measures were recorded using a behavior categorization system. Twin-singleton comparisons were made between the four younger playgroups (mean age two years) and four older playgroups (mean age three years). Twins and singletons were compared both as initiators and as objects of social contact and interaction. The playgroup situation afforded study of twin-singleton differences in both mother-directed and child-directed social behavior, as well as the role of twin-cotwin social contacts in these areas. Results indicated twins and singletons differed in both their mother-directed and child-directed social behavior. These differences were most evident in comparing younger versus older playgroups. There was little indication of twin-singleton differences at the older age level. Observational data suggested twinship afforded twins security away from their mothers in a novel play setting, thereby increasing their availability for social contacts with singleton peers. Results did not support previous proposals that twins' close relationship with each other isolates them from social contacts with other playmates or reduces their interaction with their mothers.