Although originally designed for 1-year-old children, Ainsworth’s strange situation has been adapted to measure the attachment and exploratory behavior of children between the ages of 2-4½ years-old. A fundamental feature of the strange situation is that the situation the child is placed in must elicit stress. If the strange situation fails to stress the child, it cannot serve as an adequate environment for the measurement of attachment. The preschool strange situation features several alterations to facilitate the creation of stress in older children. These modifications include a slightly longer separation, changes in the role and/or gender of the stranger, and changes in the instructions to the caregiver. Some versions of the preschool strange situations omit the stranger altogether, thus leaving the child alone in the room throughout both separations. The coding system used to interpret the attachment style expressed by the child has also been modified. Rather than focusing entirely on the expression of specific behaviors and emotions, the revised coding system assesses ways in which a variety of behaviors, such as talking, are organized to maintain and negotiate proximity and contact. Cassidy, Marvin and the MacArthur Working group published a version of the Strange Situation procedure designed for children within the age group of 3- to 4-years-old. In addition to categorizing a child’s attachment as secure, insecure/avoidant, insecure/ambivalent, and insecure/disorganized, the measure includes a seven-point avoidance scale and nine-point security scale.