The strange situation is a standardized procedure devised by Mary Ainsworth in the 1970s to observe attachment security in children within the context of caregiver relationships. It applies to infants between the age of nine and 18 months.
The procedure involves series of eight episodes lasting approximately 3 minutes each, whereby a mother, child and stranger are introduced, separated and reunited.
John Bowlby (1969) believed that attachment was an all or nothing process. However, research has shown that there are individual differences in attachment quality. Indeed, one of the primary paradigms in attachment theory is that of the security of an individual’s attachment (Ainsworth & Bell, 1970).
Ainsworth (1970) identified three main attachment styles, secure (type B), insecure avoidant (type A) and insecure ambivalent/resistant (type C). She concluded that these attachment styles were the result of early interactions with the mother.
A fourth attachment style known as disorganized was later identified (Main, & Solomon, 1990).
Main, M., & Solomon, J. (1990). Procedures for identifying infants as disorganized/disoriented during the Ainsworth Strange Situation. In M.T. Greenberg, D. Cicchetti & E.M. Cummings (Eds.), Attachment in the Preschool Years (pp. 121–160). Chicago, University of Chicago Press.