This refers to a means of testing the attachment styles of toddlers developed by a team led by Mary Ainsworth.
When the mother-figure is absent, secure children become upset, then calm down, but are happier when the mother-figure returns. Avoidant children left with a strange person do not react strongly to the sudden absence of the primary caregiver with a substitute stranger and are not strongly moved by the return of the mother-figure.
Anxious toddlers do object in the same situation and are difficult to calm down when the mother-figure returns.
Ainsworth's colleague Mary Main later added the category of disorganized/disoriented attachment for children with more intense responses.
