Strange Situation
Psychologist Mary Ainsworth's 1970s lab procedure that first documented distinct attachment patterns in young children.
In the Strange Situation, a young child plays in an unfamiliar room while a caregiver leaves and returns a few times, and researchers observe how the child reacts to the separation and reunion. Ainsworth used those reactions to identify distinct attachment patterns in children for the first time.
The Strange Situation itself is a child-development research method, not something adults take. This site's attachment style test measures the related but separate adult-relationship framework that researchers later built on top of Ainsworth's original findings.