Procedure and measures
Children were followed from birth to 15 years of age. Complete
details about all procedures and measures are documented
on the Web site of the NICHD (2009) Study of Early
Child Care and Youth Development.
Control variable: maternal age of menarche. Each mother’s
report of her own age of menarche was used to partially
control for genetic effects on her children’s timing of puberty.
Primary predictor: infant-mother attachment security.
Infant-mother attachments in our sample were assessed as
secure or insecure using the Strange Situation procedure. At
15 months of age, infants were videotaped in the Strange Situation,
a separation-reunion procedure designed to evoke
attachment behavior (Ainsworth, Blehar, Waters, & Wall,
1978). When stressed in this procedure, secure infants establish
unambiguous psychological contact with their mothers on
reunion. This contact occurs either across a distance (e.g.,
smiling, vocalizing) or physically (e.g., approaching, reaching).
Although secure infants find comfort and solace in their
mothers’ arms if distressed, insecure infants avoid such