A Biography of Mary Ainsworth

Mary Ainsworth working with a child
JHU Sheridan Libraries/Gado Archive Photos/Getty Images

Mary Ainsworth was a developmental psychologist perhaps best known for her Strange Situation assessment and contributions to the area of attachment theory. Ainsworth elaborated on Bowlby's research on attachment and developed an approach to observing a child's attachment to a caregiver.

Based on her research, she identified three major styles of attachment that children have to their parents or caregivers. In a 2002 review ranking the most eminent psychologists of the twentieth century, Ainsworth was listed as the 97th most influential psychologist, based on the frequency of journal citation, introductory psychology textbook citation, and survey response.

Mary Ainsworth: At a Glance


Birth: December 1, 1913

Death: March 21, 1999

Best Known For: Research on attachment theory and the development of the "Strange Situation" assessment.


Early Life

Mary Ainsworth was born in Glendale, Ohio. When she was 15, she read William McDougall's book Character and the Conduct of Life, which inspired her lifelong interest in psychology.

She attended the University of Toronto in the honors psychology program. After earning her BA in 1935, her MA in 1936, and her PhD in 1939, she spent several years teaching at the University of Toronto before joining the Canadian Women's Army Corp in 1942.

The Strange Situation Assessment

In 1950, she married Leonard Ainsworth and moved to London. During her time in England, Ainsworth worked at the Tavistock Clinic with psychologist John Bowlby, where she researched maternal-infant attachments. After leaving this position, she spent time researching mother-child interactions in Uganda.

After returning to the U.S., Ainsworth took a position at John Hopkins University. She divorced in 1960 and underwent therapy that contributed to her interest in psychoanalytic theory.

While teaching at John Hopkins, she began working on creating an assessment to measure attachments between mothers and children. It was here that she developed her famous "Strange Situation" assessment, in which a researcher observes a child's reactions when a mother briefly leaves her child alone in an unfamiliar room.

According to Ainsworth, the way the child behaves during the separation and upon the mother's return can reveal important information about attachment.

In her study, children between the ages of 12 and 18 months were briefly left alone in a room while the researchers observed their reactions. They were observed when the parent and child were together, when a stranger entered the room, when the parent briefly left the room, and when the parent returned.

Attachment Theory

Based on her observations and research, Ainsworth concluded that there were three main styles of attachment:

  • Secure attachment: Securely attached children seek comfort when frightened and prefer parents to strangers.
  • Anxious-avoidant attachment: Anxiously attached children are wary of strangers, exhibit great distress when a parent leaves, but are not comforted by a parent's return.
  • Anxious-resistant attachment: Avoidantly attached children show little preference for parents over strangers and seek little comfort from their caregivers.

Since these initial findings, her work has spawned countless studies into the nature of attachment and the different attachment styles between children and caregivers.

In her letters to her mentor and fellow attachment researcher John Bowlby, Ainsworth noted that she also believed different sub-types might exist within the three primary attachment styles. She also suggested that there might be other attachment styles she had not observed in her research and believed that cross-cultural variations might exist.

Major Contributions to Psychology

Mary Ainsworth's research on attachment has played an important role in our understanding of child development. In addition to Ainsworth's three styles, other researchers identified a fourth style known as disorganized-insecure attachment. 

Ainsworth's work also inspired a great deal of research on the impact these early attachment styles continue to have throughout life.

While these styles change with time and experience, researchers believe that childhood attachment styles influence adult romantic attachments. Adults with a secure romantic attachment style tend to have lasting relationships and believe love is enduring. Those with an insecure romantic attachment style believe that love is more temporary.

While her work is not without controversies, such as the extent to which early attachment styles contribute to later behavior, her observations have inspired an enormous body of research on early childhood attachment.

A Word From Verywell

Mary Ainsworth was a significant figure in the field of developmental psychology. Her research and development of the Strange Situation Assessment helped psychologists further explore the importance of early childhood attachments in child development. Her work also inspired further exploration of how early relationships continue to shape interpersonal attachments throughout life.

Frequently Asked Questions

  • Who was Mary Ainsworth?

    Mary Ainsworth was a developmental psychologist who conducted groundbreaking research on attachment theory. She is best known for her "strange situation" experiment, which helped identify the different types of attachment between children and their caregivers. Ainsworth's work on attachment theory has had a lasting impact on our understanding of the importance of early relationships.

  • What did Mary Ainsworth study?

    Mary Ainsworth studied attachment theory, which suggests that young children form bonds with their caregivers. These bonds are essential for the child's development and well-being.

    Ainsworth's most famous study is the "strange situation" experiment. In this experiment, she observed how infants and toddlers responded when their mothers left them alone with a stranger.

    This study helped identify the different attachment types between children and their caregivers. It also showed the importance of early relationships for the child's development.

  • How did Mary Ainsworth influence psychology?

    Mary Ainsworth's work on attachment theory emphasized the importance of early relationships. Her research showed that early attachments critically impact a child's development and well-being. Her work also influenced other areas of psychology, such as parenting and child care, and inspired further research on how early attachment affects adult romantic relationships.

Was this page helpful?
10 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Main, M. Mary D. Salter Ainsworth: Tribute and portrait. Psychoanalytic Inquiry. 1999;19(5):682-736. doi:10.1080/07351699909534273

  2. Haggbloom SJ, Warnick R, Warnick JE, et al. The 100 most eminent psychologists of the 20th century. Review of General Psychology. 2002;6(2):139-152. doi:10.1037/1089-2680.6.2.139

  3. O’Connell AN, ed. Models of Achievement: Reflections of Eminent Women in Psychology, Vol 2. 1st ed. New York, NY: Erlbaum; 1988.

  4. Bretherton I. Mary Ainsworth: Insightful observer and courageious theoretician. In Kimble GA, Wertheimer M, American Psychological Association. Portraits of Pioneers in Psychology, Vol. 5. Hillsdale, NJ: Erlbaum; 1991.

  5. Cassidy J, Jones JD, Shaver PR. Contributions of attachment theory and research: a framework for future research, translation, and policyDev Psychopathol. 2013;25(4 Pt 2):1415-1434. doi:10.1017/S0954579413000692

  6. Ainsworth MD, Bell SM. Attachment, exploration, and separation: Illustrated by the behavior of one-year-olds in a strange situationChild Dev. 1970;41(1):49-67. doi:10.2307/1127388

  7. Cassidy J, Jones JD, Shaver PR. Contributions of attachment theory and research: a framework for future research, translation, and policy. Dev Psychopathol. 2013;25(4 Pt 2):1415-34. doi:10.1017/S0954579413000692

  8. Hong YR, Park JS. Impact of attachment, temperament and parenting on human development. Korean J Pediatr. 2012;55(12):449-54. doi:10.3345/kjp.2012.55.12.449

  9. Landa S, Duschinsky R. Letters from Ainsworth: contesting the 'organization' of attachmentJ Can Acad Child Adolesc Psychiatry. 2013;22(2):172-177.

  10. Duschinsky R. The emergence of the disorganized/disoriented (D) attachment classification, 1979-1982. Hist Psychol. 2015;18(1):32-46.doi: 10.1037/a0038524