Mary Ainsworth, building on her Uganda and Baltimore observational studies of mother-infant pairs, designed the Strange Situation as a standardized twenty-minute laboratory procedure to observe how one- and two-year-olds use a caregiver as a secure base and respond to brief separations and reunions. Roughly one hundred Baltimore infants and their mothers were observed through eight short episodes in which a stranger and the mother left and re-entered the room in a set sequence. From how an infant explored, sought comfort, and greeted the returning mother, Ainsworth classified attachment into secure, insecure-avoidant, and insecure-resistant (ambivalent) patterns, published in full in Patterns of Attachment (1978) with Blehar, Waters, and Wall. A fourth category, disorganized attachment, was added later by Main and Solomon in 1990. The procedure became the standard research instrument for testing John Bowlby's attachment theory and remains the most widely used method for classifying infant attachment.
Facts
Key FindingSourced to the subject's own accountAbout 70 percent of the Baltimore infants were classified secure, 15 percent insecure-avoidant, and 15 percent insecure-resistant, establishing three attachment patterns from how infants used a caregiver as a secure base. 1 Study YearSourced to the subject's own account Cross-Tradition Connections
Associated With
The Strange Situation is the standard research instrument for testing and operationalizing Bowlby's attachment theory.
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Sources
1. SimplyPsychology: Mary Ainsworth
Simply PsychologyMary Ainsworth Strange Situation Experiment, procedure sectionQuote, Mary Ainsworth Strange Situation Experiment, procedure section
The infant's behavior was observed during eight pre-determined episodes, most lasting about three minutes each.
1. SimplyPsychology: Mary Ainsworth
Simply PsychologyMary Ainsworth Strange Situation Experiment, findings sectionQuote, Mary Ainsworth Strange Situation Experiment, findings section
Ainsworth and her colleagues (1978) identified three main attachment styles, secure (type B), insecure avoidant (type A), and insecure ambivalent/resistant (type C).
1. SimplyPsychology: Mary Ainsworth
Simply PsychologyMary Ainsworth Strange Situation Experiment, timeline sectionQuote, Mary Ainsworth Strange Situation Experiment, timeline section
she and Barbara Wittig designed the Strange Situation (Ainsworth & Wittig, 1969).
1. SimplyPsychology: Mary Ainsworth
Simply PsychologyAssociated With: Attachment Theory, Mary Ainsworth Strange Situation Experiment, biography sectionQuote, Associated With: Attachment Theory, Mary Ainsworth Strange Situation Experiment, biography section
In late 1950, Ainsworth and her husband Leonard moved to London so he could complete his doctorate at University College.
Open Questions (1 open question)
Are Ainsworth's Strange Situation attachment classifications culturally universal, or do they reflect Western caregiving norms?
Attachment theory's secure/insecure classifications were developed and normed on a Western, mostly American middle-class sample, and the social milieux and caregiving arrangements the theory assumes vary widely across cultures, so it remains disputed whether the same classifications and their developmental meaning transfer to societies with different childrearing practices.
What would resolve this Attachment measures independently developed and validated within non-Western caregiving contexts, compared against the Strange Situation's own classifications and outcomes.
Wikipedia: Attachment Theory
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