Attachment and Health
John Bowlby and Mary Ainsworth developed attachment theory in the 1960s while investigating the effects of maternal separation on infant development. The development of the Strange Situation task in 1965 by Ainsworth and Wittig allowed researchers to systematically investigate the attachment system operating between children and their parents. The Strange Situation involves separating infant-parent dyads and observing infant behaviours upon reunion. Infant behaviour tended to follow patterns, leading to the development of three attachment categories: Secure, Anxious-Avoidant, and Anxious-Resistant. In 1990, Ainsworth added a new category, championed by Mary Main, called Disorganized/Disoriented attachment, characterized by its less reliable pattern of behaviour.
Attachment therapy
Attachment therapy prospered during the 1980s and '90s as a consequence of both the influx of older adopted orphans from Eastern European and third world countries and the inclusion of reactive attachment disorder in the 1980 Diagnostic and Statistical Manual of Mental Disorders which attachment therapists adopted as an alternative name for their existing unvalidated diagnosis of attachment disorder.