This research is tested on animals and humans. In accordance with this, adult relationships are also being studied. When exposed to a fairly normal stimuli the children with insecure attachment showed a dramatic increase in physiological reactions while the children with secure attachment showed no increase in cortisol. These children had more ability to cope with everyday situations. There were a variety of doctors collaborating on these studies and they even went a step further to test their data on monkeys and different cultures such as Rumania.
Researchers expose infants to a mild stress by separating then from their mothers for a few minutes.
Secure infants re establish positive contact with their mothers following the separation. Insecure infants either ignore and avoid their mothers or are not easily comforted by them with their return. It seems that equal numbers of children in this study showed each reaction. I have read a great deal about the strange situation and this is a more current study illustrating the same point except this one incorporating the minimal effect of child care on mother-infant attachment. This study was initiated by the National Institute of Child Health and Human Development.