Psychology › Development & attachment › Attachment theory (John Bowlby)
Ainsworth's Strange Situation and attachment styles
1970; 1978· Finding or experiment
Well replicatedStrong, repeated evidence.
Mary Ainsworth's 20-minute lab test of how toddlers react to brief separations from a parent, revealing attachment styles.
See it on the Psychology map →What it says
A child of about 12 to 18 months plays in an unfamiliar room with a parent; a stranger enters; the parent leaves twice and returns. The reunion is key. Secure infants, about two-thirds in most samples, seek comfort and settle. Avoidant infants ignore the parent; resistant ones cling but stay upset. In 1986 Mary Main and Judith Solomon added 'disorganized', more common where care is frightening or chaotic. Sensitive, responsive parenting at home predicted security.
Why it matters
It made attachment measurable, enabling decades of research on caregiving, daycare and later outcomes; it remains the standard laboratory tool for infant attachment.
The evidence
Status: well replicated as a measure. A 1988 review of nearly 2,000 tests in eight countries found secure attachment most common everywhere, though avoidant shares were higher in Germany and resistant ones in Japan.
Open questions
How much results reflect a baby's inborn temperament rather than parenting, and whether a procedure built on American norms fits cultures where separations are rare.
Connections (3)
▸Ainsworth's Strange Situation and attachment styles measures Attachment theory (John Bowlby)Well replicated
The connection
Bowlby's theory predicted that a securely attached baby uses the parent as a base for exploring and a haven when stressed, but gave no way to measure it. Ainsworth's lab test supplies mild, rising stress (an unfamiliar room, a stranger, two brief separations) and codes how the baby seeks the parent at reunion, sorting babies into attachment styles.
Who showed it and when
Mary Ainsworth at Johns Hopkins University, Baltimore, 1970, building on her home observations in Uganda (1954–55) and Baltimore; full account in Patterns of Attachment (1978).
The evidence
Home observations of sensitive parenting predicted the lab results; trained coders agree well on classifications, and the test has been used in thousands of studies.
Open questions
Whether a short lab test captures a lasting bond; classifications can change over months, especially when family circumstances change.
▸Ainsworth's Strange Situation and attachment styles is partly confounded with Temperament in infantsMixed evidence
The connection
The Strange Situation classifies babies by how they react when a parent leaves and returns. Critics such as Jerome Kagan argued these reactions partly reflect inborn temperament, how easily a baby gets upset, rather than the quality of care. Studies suggest temperament affects how much babies cry more than whether they are classed as securely attached.
Who showed it and when
Debated from the early 1980s by Kagan at Harvard and attachment researchers; tested in many infant studies through the 2010s.
How solid is it?
Babies often have different attachment classifications with mother and father, which temperament alone cannot explain; meta-analyses find only weak links between temperament and security.
Open questions
How temperament and caregiving interact: some argue easily upset babies are the most affected by the quality of care they receive.
▸Close relationships: adult attachment and marriage adapted the categories of Ainsworth's Strange Situation and attachment stylesMixed evidence
The connection
Hazan and Shaver turned Ainsworth's three infant types into three short descriptions of adult romance, secure, avoidant and anxious-ambivalent, and asked adults to pick one. The shares came out close to infant ones: about 56% secure, 25% avoidant, 19% anxious. Later researchers replaced the types with two scales, anxiety and avoidance.
Who showed it and when
Hazan and Shaver's 1987 newspaper survey in Denver; Kim Bartholomew proposed four types in 1991; Kelly Brennan's team built the two-scale measure in 1998.
How solid is it?
The similar percentages are documented, but matching shares do not prove the same people kept the same style from infancy.
Open questions
Whether adult romantic styles really are the infant patterns grown up, or a separate thing that borrows the vocabulary.