Ainsworth, Mary Dinsmore Salter

Psychologists and Their Theories for Students. Editor: Kristine Krapp. Volume 1, Gale, 2005.

Brief Overview

If John Bowlby was the father of attachment theory, Mary Ainsworth could certainly be considered its mother. Together the two started a rich field of study that has changed the face of developmental psychology and profoundly influenced theories of parenting.

In brief, attachment theory is based on the concept that all infants have a fundamental need to develop a close relationship, or attachment, to their mother (or primary caregiver). They initiate attempts at attachment through attachment behaviors such as smiling at, hugging, and moving toward their caregiver. If the mother or caregiver answers consistently and appropriately with sensitive and responsive behavior such as comforting, holding, hugging, and stroking, the attachment bond is strengthened and secure. When responses are inconsistent, insensitive, or inappropriate, an insecure attachment is formed.

Although it was Ainsworth’s London colleague John Bowlby who first theorized that there was something beyond the mother-infant bond than a fulfillment of basic physical needs (i.e., food and shelter), Ainsworth provided attachment theory with both the empirical data and the psychological scales and methods for validating Bowlby’s hypotheses. She also further refined attachment theory with concepts such as mother as secure base and organizations of attachment.

Ainsworth pioneered the concept of longitudinal, systematic, yet naturalistic observation in the home.

Her field studies of mother-infant dyads and narrative data collection, first in Uganda and later in Baltimore, were unprecedented, although they were at first frequently criticized as having too “unscientific” a tone. Ainsworth’s “strange situation” laboratory procedure is still used in developmental research today.

The “strange situation” technique involves a series of separations and reunions between an infant and his or her mother, which take place in a laboratory setting. A stranger is also introduced at several points in the protocol. As with all of Ainsworth’s clinical studies, observers carefully monitor and transcribe how the procedure unfolds. The infant’s reaction to the separation and behavior towards his or her mother upon reunion provides a framework for determining the type of attachment he or she has to the mother. Ainsworth had determined three main categories of infant attachment: secure, insecure-avoidant, and insecure-resistant.

Finally, throughout Ainsworth’s lengthy academic and teaching career, she mentored dozens of students who would go on to make significant contributions to broadening the field of attachment theory in their own right. One of these, student Mary Main, summed up what made Ainsworth such a remarkable mentor:

First, she required rather than simply recommended independence on the part of her students, meaning that rather than utilizing her already-collected data for a thesis, each student had to design and carry out a complete project, bringing in their own research participants and drawing their own new conclusions. Second, she believed that a person’s academic life was not the whole of their life, but only a portion … Third, she wrote our better ideas down in an endeavor not to become confused later and think that she herself had come up with them. Fourth, she worked very hard on helping us with our work.

Her love of both teaching and research kept Ainsworth working well past her official retirement at age 80. She was a co-recipient of the APA’s first mentoring award in 1998, the same year she was also honored with one of the APA’s highest recognitions—the Gold Medal Award for Life Achievement in the Science of Psychology.

Principal Publications

  • “The Effects of Maternal Deprivation: A review of findings and controversy in the context of research strategy.” Deprivation of Maternal Care: A Reassessment of its Effects. World Health Organization, Public Health Papers 14 (1962): 97-165.
  • With J. Bowlby. Child Care and the Growth of Love, 2nd ed. London: Penguin, 1965.
  • Infancy in Uganda: Infant Care and the Growth of Love. Baltimore: Johns Hopkins University Press, 1967.
  • With S. M. Bell. “Attachment, Exploration, and Separation: Illustrated by the behavior of one-year-olds in a strange situation.” Child Development 41: 49-67, 1970.
  • With M. C. Blehar, E. Waters, and S. Walls. Patterns of Attachment: A Psychological Study of the Strange Situation. Hillsdale, NJ: Lawrence Erlbaum, 1978.
  • “Attachments Beyond Infancy.” American Psychologist 44 (1989): 709-16.
  • With J. Bowlby. “An Ethological Approach to Personality Development.” American Psychologist 46 (1991): 331-41.


Mary Dinsmore Salter Ainsworth was born in Glendale, Ohio, in 1913, the oldest of three daughters of Charles and Mary Salter. Ainsworth showed a talent for academics early in life, reportedly learning to read at the age of three. The Salters valued education; both Charles and Mary were graduates of Dickinson College in Pennsylvania. Ainsworth recalls the weekly visits the family took to the library and the high academic expectations her parents had for all three of their girls to attend college.

Charles Morgan Salter was employed by a Cincinnati-based manufacturing firm, and when Ainsworth was five the family moved to Toronto after his company relocated him to a branch office. Her father eventually became branch President of Aluminum Goods, Ltd., and in 1931 Ainsworth and her parents became naturalized Canadian citizens.

Mary Main, a behavioral psychologist and student of Ainsworth’s, recounts that Ainsworth described a contentious relationship with her mother that was characterized by her mother’s interference in personal matters and jealousy of the closeness she had with her father. Ainsworth herself never commented publicly on any disharmony within the family, stating they were “a close-knit family, with a not unusual mixture of warmth and tensions and deficiencies.”

Ainsworth excelled in school and entered the University of Toronto in 1929 at the age of 16, entering the psychology program in her second year. In an autobiographical essay published in the 1983 book Models of Achievement: Reflections of Eminent Women in Psychology, Ainsworth recalls her first realization that she wanted to enter the field of psychology:

When I was 15 and in my final year in high school, one of the books brought home was William McDougall’s Character and the Conduct of Life (1927), which I read with great excitement. It had not previously occurred to me that one might look within oneself for some explanation of how one felt and behaved, rather than feeling entirely at the mercy of external forces. What a vista that opened up! I decided thereupon to become a psychologist.

Remaining at the University of Toronto for graduate school, Ainsworth earned her master’s degree in 1936 and her Ph.D. in 1939. She worked as a teaching assistant to Professor Edward Bott, head of the Psychology Department and one of Ainsworth’s mentors. Later, she would cite Bott as the influence who helped her develop the attitude that science is a “state of mind.”

Another influential mentor during her graduate years was Professor William Blatz, who had developed a personality theory called security theory. Security theory was based on the idea that children who feel secure in their dependence on their parents are better equipped to adjust and cope with experiences in the outside world, because they are assured that their parent(s) will always be there for them. Those who are insecure in the parent-child relationship will not be as willing to act independently of their parents and explore the world around them.

As children grow into adults, the relationship evolves and the person(s) with whom they find security changes; children become less dependent on their parents and more on their peers, until as adults they become securely dependent on a spouse or partner. The concept of security theory would help to shape Ainsworth’s later work in attachment theory in several important ways. With Blatz’s guidance and urging, Ainsworth wrote her doctoral dissertation, “An Evaluation of Adjustment Based on the Concept of Security,” which involved creating and testing new psychometric scales (or tests) for young adults that quantitatively evaluated their relationships with their parents and peers.

Ainsworth also credits Professor Sperrin Chant with shaping her future destiny as both a psychologist and later a teacher and mentor for her own students. Chant oversaw her master’s thesis, an investigation into emotions and galvanic skin response (GSR). GSR is a measurement of the electrical properties of the skin, which change in response to stress and anxiety. It is one of the same technologies used in today’s polygraph, or lie detector test. Ainsworth also coauthored a 1937 article with Chant on the topic in the Journal of Educational Psychology entitled “The Measurement of Attitude Toward War and the Galvanic Skin Response.”

After completing her doctoral dissertation and graduating with a Ph.D., Ainsworth continued on at the University of Toronto as a lecturer beginning in the fall of 1939. Shortly thereafter with the advent of World War II, many of her Toronto colleagues and mentors left the University to assist in the war effort. Ainsworth herself joined them in 1942, enlisting in the Canadian Women’s Army Corps. She first served as an army examiner in Kitchener, Ontario, using her background in psychology and personality development to work in personnel selection, which involved interviewing and assessing recruits and recommending a placement based on the results. After several months in Kitchener, Ainsworth transferred to Ottawa, where she attained the rank of major in less than a year. She also spent several months abroad working with the personnel service of the British Army.

At the conclusion of the war, Ainsworth was tapped for a post at the Department of Veteran’s Affairs. She served as the Superintendent for Women’s Rehabilitation for about a year, and then, longing to return to her alma mater and tiring of the heavy load of administrative work her position required, she accepted a post as assistant professor at the University of Toronto, teaching introductory psychology and experimental psychology to undergrad students.

In preparation for teaching a graduate-level course on personality assessments, Ainsworth began to study psychometric and neuropsychiatric tests—including the Rorschach (i.e., ‘inkblot test’) and the thematic apperception test (TAT)—in earnest, taking several workshops and volunteering her clinical services at the local Department of Veterans Affairs hospital. She took several workshops with well-known psychologist Bruno Klopfer, who had developed a scoring and administration technique for the Rorschach. Ainsworth would later collaborate with Klopfer on the revision of his book on the subject, Developments in the Rorschach Technique: Vol. 1.

Over the next several years Ainsworth taught and, along with mentor William Blatz, co-directed a research team developing psychological testing scales associated with Blatz’s security theory. In 1950, she married one of the graduate students on that team, Leonard Ainsworth, and the newlyweds moved to London, where Leonard had been accepted at University College to do his doctoral work after receiving his master’s degree at Toronto.

A former colleague of Ainsworth’s from her days in the Canadian armed services told her about a research position at London’s Tavistock Clinic under Dr. John Bowlby, who was investigating the impact of early separation from one’s mother on childhood personality development (see sidebar). Ainsworth was hired, marking the beginning of a lifelong professional association with Bowlby, and worked at Tavistock through the end of 1953 while her husband Leonard completed his Ph.D.

The Ainsworths moved to Africa in 1954 after Leonard was hired as a research psychologist at the East African Institute of Social Research in Kampala, Uganda. It was here where Ainsworth performed observational studies on infant-mother interaction and gathered the data that would later become her landmark book Infancy in Uganda.

In 1955 Leonard Ainsworth landed a position in Baltimore, Maryland as a forensic psychologist, and Ainsworth quickly found an appointment as a lecturer at Johns Hopkins and a part-time clinical psychologist at Sheppard and Enoch Pratt Hospital.

Mary and Leonard Ainsworth divorced in 1960. Ainsworth continued to work in earnest, but as a result of what she called “a depressive reaction to divorce,” she also entered long-term personal psychoanalysis. Retrospectively, Ainsworth credits her eight years of psychoanalysis as improving her productivity and exposing her to Freudian theory that expanded her knowledge and understanding as a psychologist.

Looking for an opportunity to delve back into research, Ainsworth shifted focus at Johns Hopkins, leaving the part-time clinical work at the hospital in 1961 and becoming first an associate professor and then a full professor in developmental psychology. In 1962 Ainsworth embarked on what is perhaps her most significant and influential contribution to developmental psychology—short-term longitudinal research into the development of infant-mother attachment sometimes referred to as “the Baltimore study.”

Ainsworth and her research team went into the homes of 26 area women and observed their interaction with their infants in approximate four-hour blocks every three weeks, totaling up to 80 hours on observation over the first year of life. The method built on her previous work in Uganda. In fact, the Baltimore study was designed as a “replication” study for the Uganda work, to validate its findings. But the experience would prove to broaden the scope of that study and ultimately spur Ainsworth to develop one of attachment theory’s most useful clinical tools—the “strange situation” technique.

Although her observations of the maternal-infant relationship were quite astute, Ainsworth herself never had any children of her own. This was more a factor of timing than anything else; she often spoke of her wish to have become a mother herself, but she married late (at age 37) and divorced a decade later. Ainsworth never remarried, and according to student Mary Main, her next serious relationship didn’t occur until she was in her 80s.

After over a decade at Johns Hopkins, Ainsworth was nearing the usual retirement age at that institution (60) but was as professionally productive as ever. After investigating her options, she moved on to the University of Virginia in the fall of 1975 as a visiting professor. There she helped to develop the University’s psychology training program, which gave students the opportunity to do clinical casework under supervision. The Mary D. Ainsworth Psychological Clinic continues to provide mental health services to the University of Virginia community today.

Ainsworth retired in the capacity of professor emeritus in 1984, but remained active in research until the early 1990s, coauthoring several more papers with Bowlby and others and providing the assistance of her own insight and opinions on the attachment research of her former students and colleagues. She was awarded two of the APA’s highest honors in 1998—the Mentor Award in Developmental Psychology and the Gold Medal Award for Life Achievement in the Science of Psychology. Ainsworth lived the remainder of her life in Charlottesville, Virginia, where she died in 1999 after a lengthy illness following a stroke.

In addition to the APA awards, Ainsworth was bestowed with numerous honors, awards, and official appointments throughout her career, including: Distinguished Contribution Award, Maryland Psychological Association (1973); President of the Society for Research in Child Development (1977-79); Distinguished Scientific Contribution Award, Virginia Psychological Association (1983); Distinguished Scientific Contribution Award, Division 12, APA (1984); G. Stanley Hall Award, Division 7, APA (1984); Salmon Lecturer, Salmon Committee on Psychiatry and Mental Hygiene, New York Academy of Medicine (1984); William T. Grant Lecturer in Behavioral Pediatrics, Society for Behavioral Pediatrics (1985); Award for Distinguished Contributions to Child Development Research, Society for Research in Child Development (1985); Award for Distinguished Professional Contribution to Knowledge, APA (1987); C. Anderson Aldrich Award in Child Development, American Academy of Pediatrics (1987); Distinctive Achievement Award, Virginia Association for Infant Mental Health (1989); Honorary Fellowship, Royal College of Psychiatrists (1989); Distinguished Scientific Contribution Award, APA (1989); American Academy of Arts and Sciences (1992); Distinguished Professional Contribution Award, Division 12, APA (1994); and International Society for the Study of Personal Relationships Distinguished Career Award (1996).


Mary Ainsworth’s work in attachment theory had its roots in her research with John Bowlby at Tavistock. Bowlby and another colleague, James Robertson, first introduced her to the naturalistic method of observation and descriptive statistics that would later become her trademark.

Before Bowlby, the prevailing view among psychologists and psychoanalysts was that infants bonded with their mothers simply because the mother fed the child and met his or her physical needs. Bowlby was also a maverick in his belief that evolutionary and ethological theory both influenced personality development and the attachment process (see sidebar). Ethology, or the study of animal (and human) behavior and adaptation in natural surroundings, particularly influenced Ainsworth’s work. While Ainsworth initially questioned the place of ethology in attachment formation, she later came to embrace the idea. Bowlby’s theory of attachment was based on the idea that a child’s development is tied closely to the bond he or she has with the mother, which was ultimately either a secure or an insecure one. From an ethological standpoint, attachment was necessary for infant survival—the mother being the source of the infant’s food, security, and shelter.

Ainsworth took Bowlby’s theories and put them to the empirical test, using innovative new field and laboratory techniques to do so. Along the way, she refined attachment theory further and contributed the concept of infant defense systems, mother as secure base, and organizations or patterns of attachment.

Patterns of Attachment

Main points Central to Ainsworth’s work on attachment is the concept of mother as “a secure base.” As early as 1940, influenced by mentor William Blatz and his security theory, she wrote about the essential role of family security to provide a secure base for individual growth. Later, in her writings on the Uganda home studies, she describes infants using their mothers as a secure base for their own exploration. The secure child is able to leave his or her mother’s side and investigate surroundings because he or she knows through experience that the mother is there if needed.

Ainsworth’s home studies of mother-infant dyads (i.e., couples) first in Uganda and then in Baltimore were unique in that they were longitudinal (i.e., long-term; nine months for Uganda and 12 months for Baltimore), and used carefully compiled narrative data gathered by trained observers over a substantial amount of home visit time (i.e., an average of 72 hours over one year in Baltimore).

Ainsworth’s Uganda studies found three classifications or patterns of infant attachment—secure, insecure, or non-attached. Later, in her Baltimore replication studies, she refined the classifications based on additional data from the “strange situation” laboratory procedure, resulting in three categories—secure, avoidant (also called anxious-avoidant or insecure-avoidant), and resistant (also called anxious-resistant or insecure-ambivalent/resistant).

Avoidant infants (a.k.a. Group A) became focused on exploration to the exclusion of all else (including mother) in the strange situation environment. At home, however, they were anxious and often angry, and wouldn’t tolerate separation from their mother, who rejected their advances through her words and actions. Ainsworth explained that the seemingly incongruous exploratory behavior of avoidant infants in the strange situation setting was a defensive (or adaptive) reaction to their life experience of their mother’s rejection. She outlined specific qualities of maternal behavior that were associated with avoidant attachments—rejection, physical rejection (i.e., pulling away from kisses or hugs), submerged anger (i.e., holding anger in), and a lack of awareness of infant cues.

Secure infants (a.k.a. Group B) were those with the strongest mother-infant attachment. They considered their mother what Ainsworth called a secure base, meaning that they would return to her for reassurance and comfort while they explored both familiar and unfamiliar environments. They were happy and responsive to her, and did not become upset during brief separations in the home environment. However, they did experience separation anxiety when put in the strange situation environment, but they were easily calmed and reinvolved in exploration once the mother returned.

Resistant infants (a.k.a. Group C) tended to cling to their mothers and become overly preoccupied with her whereabouts in the strange situation environment. They also avoided exploration in her absence. Ainsworth theorized this was due to the mother’s insensitive and inconsistent reactions to the child at home. These children either became unusually distant and detached (i.e., ambivalent) or expressed anger (i.e., resistant) in the home environment.

Ainsworth saw all of these attachment patterns as the result of defensive behaviors formed through the child’s life experience with the mother (or other attachment figure). She developed a series of scales that rated maternal behavior in four areas: sensitivity vs. insensitivity to infant signals, cooperation vs. interference with ongoing behavior, psychological and physical availability vs. neglect, and acceptance vs. rejection of infant’s needs. Based on these scales, secure infants had mothers who scored high in sensitivity, cooperation, availability, and acceptance.

Explanation In Infancy in Uganda, Ainsworth first describes attachment behaviors in infants that are cues for maternal response. They include smiling, crying, adjusting posture, suckling, looking at the mother, listening to the mother, vocalizing in response to her voice, “scrambling” (i.e., climbing) over her, moving nearer, following her, and clinging to her. Ainsworth is quite clear in explaining that these behaviors are not signs of attachment in and of themselves:

They are the patterns of behavior through which attachment grows. The baby is not attached to anyone at first. He does not somehow become attached and then show it by smiling at the loved person and crying when she leaves him. He gradually becomes attached.

In other words, secure attachment isn’t inherent at birth, but develops through an interplay of infant cues and maternal response.

In everyday encounters with new experiences, the mother acts as what Ainsworth called the secure base for the child. For children with a secure attachment, the mother serves as a provider of safety and comfort, whom the child can turn to for help in situations where he or she feels in danger (such as when the stranger enters in the strange situation protocol.) Having access to a secure base also allows the infant to engage in exploratory behavior, with the knowledge that his or her mother will be there to help if needed. Again, whether or not the child perceives the mother as a secure base depends on their interaction and whether the child’s attachment behavior is responded to. Ainsworth believed the first year of life was most crucial in this relationship.

Infants who do not have a secure base, and therefore don’t have a strong and secure attachment with their mother or primary caregiver, won’t explore their surroundings as readily as secure children and therefore miss out on important cognitive stimuli, or “hands on” learning experiences. Insecure attachment in infancy has been linked to later problems in childhood and adolescence, including conduct disorder, anxiety disorders, and reactive attachment disorder. In addition, stress associated with insecure attachments has been shown to negatively impact neurological development of the limbic system of the brain and can also trigger the chronic release of potentially damaging stress hormones.

Ainsworth’s patterns or classifications of attachment were developed from two main data sources—home visits to the mother-infant study subjects, and a laboratory-based procedure she developed known as the strange situation method.

The strange situation protocol measured infant attachment behavior by exposing an infant to a series of separations and reunions from its mother, performed in a laboratory. It was originally designed for children up to one year of age, although later refinements pushed the age limit to 18 months.

In the procedure, a mother and baby are brought into a room that contains a variety of new toys. Over a period of approximately 20 minutes, the child is periodically separated from the mother, left with a stranger, and then reunited with his mother. Observers gauge the infant’s interest in the toys, reaction to separation and reunion, and interaction with the stranger.

The strange situation technique uses the following protocol:

  • Mother, baby, and observer enter the room (30 seconds).
  • Observer leaves and mother lets baby explore toys and surroundings (three minutes).
  • Stranger enters the room quietly, converses with the mother, and then approaches the baby while the mother leaves (three minutes).
  • Stranger remains with the baby (three minutes).
  • Mother enters and stranger leaves, mother interests baby in the toys again (three minutes).
  • Mother says goodbye to baby and leaves baby alone (three minutes).
  • Stranger enters and visits with baby (three minutes).
  • Mother returns and picks baby up and stranger leaves quietly (three minutes).

How the child deals with the separations, his or her response to the stranger and the mother, and his or her willingness to explore the unfamiliar surroundings and use mother as a secure base are observed, and provide insight into the relationship between mother and child and their pattern of attachment.

Ainsworth devised a scoring system that examined six dimensions of behavior in the infant:

  • Proximity-seeking and contact-seeking behavior. Child moves close to the mother or seeks physical contact with her (i.e., grabbing her hand).
  • Contact-maintaining behavior. Clinging, getting back up on lap after being set down.
  • Avoidance. Ignoring mother and/or stranger.
  • Resistance. Squirming away from, hitting, pushing away adult-initiated contact.
  • Searching. Looking around for the mother, approaching the door after she leaves the room, staring or approaching her empty chair.
  • Distance interaction. Smiling across the room, vocalizing to the mother or stranger.

Based on the scoring criteria from these measurements, infant attachments are categorized as avoidant, secure, or resistant.

While Ainsworth performed some of the Baltimore home visits herself, she also sent many graduate and undergrad students out as trained observers. She required her students to make an advance visit to mother-infant pairs to clearly explain the nature of the research, and obtain informed consent. All observers were carefully trained to recognize and document attachment behaviors. Throughout her career, Ainsworth believed in the absolute value of this type of home-visit field work, and expressed disdain for strange situation studies that didn’t include an account of additional home observation.

Examples In her narratives of the Uganda mother-child pairs, Ainsworth offered some illustrative cases of secure and insecure attachment relationships. William was one memorable example of a securely attached child.

William was the youngest of 10 children, and there was also a foster child. The mother, single-handed, had reared all of these children, grown their food and prepared it, made many of their clothes, and looked after a large mud and wattle house, which was tastefully decorated and graced by a flower garden. She was a relaxed, serene person, who could talk to us in an unhurried way, devote time to playful, intimate interchange with William, and also concern herself with the other children according to their needs… She used a wheelbarrow as a pram, and there lay William, nested amid snowy white cotton cloths. The wheelbarrow could be moved from place to place—out to the garden where his mother worked, or under the shade tree where the other children were playing, and never out of the earshot of some responsible person.

In contrast, Ainsworth offers this description of an insecure infant.

Sulaimani’s mother was a slip of a girl, still in her teens. This was her first baby, and both she and he were unhappy. She had to do most of the garden work, but had no satisfactory arrangement for Sulaimani’s care while she was gone. He cried so much that his mother was at her wit’s end, and could not behave consistently. Sometimes she was tender and indulgent, and sometimes she was rough and angry in the way she picked him up, slung him over her back, and rocked him. Sometimes she just let him cry and cry.

Mothers who form secure attachments with their infants tend to be at ease and secure in their own life relationships. Long-term research has indicated that those infants who start life with secure attachments are more likely to perpetuate the behavior when they have children of their own. Conversely, those with insecure attachments in childhood often grow up to form insecure attachments with their children unless they are able to develop healthier attachment relationships later in life and in adulthood.

Historical Context

The very fact that Mary Ainsworth entered the University of Toronto at age 16 was a testament to her remarkable will and intelligence. For it wasn’t until that year (1929) that Canada would recognize women officially and by law as “persons” and grant them the right to serve in the Senate. Fortunately Ainsworth had chosen a more progressive institution for her studies; the University of Toronto’s Psychology Department was known for its large number of female graduate students and equal treatment of both genders. While the University opened its doors to women many years earlier (1884), all of its facilities would not be fully accessible to women until as late as the 1970s.

The advent of World War II did allow a number of prominent women in psychology the opportunity to move into important and high-profile academic and clinical positions as men left to contribute to the war effort. Although Ainsworth initially stayed at the University of Toronto and continued her work there, she soon followed the path of her male colleagues. Interestingly, her future colleague John Bowlby was doing the same type of work for the armed forces overseas. Both did active duty in the field of personnel selection during World War II. Ainsworth credits her work with the Canadian Women’s Army Corps during the war as providing her with practical skills in both administration and clinical psychology (e.g., test administration, clinical interviews) that would serve her well later in her career.

The war also set the stage for John Bowlby’s initial work in attachment and separation theory that would later inspire Ainsworth to delve deeper into maternal-infant separation. During the incessant bombing of the Battle of Britain, children from London and other urban centers were evacuated and sent to the safety of estates in the countryside, where they were cared for by healthcare professionals and childcare experts. Bowlby studied the impact of this sudden parental separation on the children (particularly the younger ones), many of whom had become withdrawn and depressed and had ceased to engage in play and other natural childhood behaviors. Soon after his focus turned to the plight of children in hospitals, at which point Ainsworth would join his research team at Tavistock.

Climbing the academic ladder at a time when women generally had a significant disadvantage in terms of pay and opportunity to their male counterparts, Ainsworth herself minimizes the significance of her accomplishments in academics, saying that the only time in her career that she ever experienced gender discrimination was when the senate of Queens University vetoed her nomination as head of their psychology department based on her sex (a position she wasn’t especially keen on accepting to begin with).

However, Ainsworth student Mary Main recounts that Ainsworth was the first woman to break the “men only” rule for dining in the Johns Hopkins Club:

Without fanfare, she succeeded in integrating this facility simply by—wearing, as she later reported, her best suit and a rose corsage—sitting alone one day at a center table until she was, very eventually, waited on. After that, as she knew, the precedent had been set, and she began taking her many female graduate students to dinner there.

Ainsworth also took the initiative for breaking down gender barriers in regards to salary at that institution.

Attachment theory was coming into its own in the 1960s and ’70s, coinciding with the women’s liberation movement. Ainsworth and Bowlby both faced criticism on their emphasis of mother as primary caregiver from those who believed that women had been relegated to that role for far too long. Ainsworth herself had this to say about the theoretical impact of her work on the women’s movement:

By some it has been viewed as a stroke against women’s liberation, since it has highlighted the importance of sensitive responsiveness to infant behavioral cues on the part of the mother figure and the desirability of continuity of the infant’s relationship with that figure, unbroken by separations that are unduly long or frequent. It has been assumed that I believe in full-time mothering during the child’s earliest years, and indeed this does seem to be the most usual way of ensuring adequate responsiveness and continuity. I acknowledge that satisfactory supplementary mothering arrangements can and have been made by a not inconsiderable few. Had I myself had the children for whom I vainly longed, I like to believe that I could have arrived at some satisfactory combination of mothering and a career, but I do not believe that there is any universal, easy, ready-made solution to the problem.

Critical Response

The field observation techniques of Mary Ainsworth were perhaps the most unorthodox, and thus most criticized, aspect of her research among contemporaries. In fact, after her Baltimore study, Ainsworth had difficulty getting a grant for another longitudinal study of the same type because most funding entities considered her original sample size too small and her clinically focused interview technique too far afield.

Ainsworth was also initially taken to task for “non-objective” language in case reports describing mother-infant interaction. Descriptive terms such as “sensitive” and “tender” were considered too subjective by many scientists, who believed that there was only value in concrete, measurable phenomena.

Unlike other research psychologists of her era, Ainsworth looked at all of her observational data in context in order to uncover its meaning, and sought to identify relationship patterns. That is, instead of counting the number of infant smiles and steps towards the mother and using this “frequency” data as a barometer of the level and nature of attachment, she analyzed all of the situational information with each event (e.g., maternal and infant mood, physical surroundings, and larger issues such as cultural and social influences). Student Mary Main points out that this tendency was likely a result of the value Ainsworth placed on psychoanalysis. In Ainsworth’s own words from Patterns of Attachment:

We do not consider measures of the strength of proximity and contact seeking—let alone measures of the frequency of smiling, vocalization, or looking—as measures of the strength of attachment. The very fact that there is such a shift in the nature and intensity of attachment behavior under different conditions and levels of activation suggests that the strength of attachment behavior reflects the situational intensity of activation rather than some postulated underlying strength of the bond between infant and attachment figure. We … have had difficulty in convincing others—so ingrained in various current psychological paradigms is the notion that any construct such as attachment must have a high-low dimension of strength or intensity.

Ainsworth also made a point of seeking out answers for those cases that did not “fit the pattern” that the rest of the group fell into, a tendency that was out of character for the research psychology field at the time. When a number of her mother-infant dyads in her Baltimore study group did not neatly fit preconceived behavioral patterns, she continued to analyze and re-analyze the data until she could construct sub-categorizations that explained every case in her study sample. This commitment to accounting for individual differences instead of going with the group trends was considered peculiar by some of her contemporaries.

Behavioral learning theorists also took issue with Ainsworth’s conclusion, gathered from the Baltimore data, that mothers who responded sensitively to their children’s cries in the first few months of life had a better and more secure relationship with the infant throughout the first year. They believed that attending to a crying child only served to reinforce the crying behavior and perpetuate it. Ultimately, Ainsworth’s findings would have a major impact on parenting theory and parental attitudes towards letting an infant “cry it out” versus responding to their needs.

Among more modern theorists, developmental psychologist Jerome Kagan is a vocal opponent of attachment theory. Kagan endorses the temperament view of mother-infant interaction, espousing that a secure or insecure attachment is not the product of maternal attention, but instead of genetic predisposition that forms infant temperament or personality. In other words, babies are born already pre-coded for the type of attachments they will form.

Although researchers have brought Ainsworth’s strange situation protocol to Germany, Israel, and other countries, several studies have demonstrated that the strange situation does not necessarily apply across all cultures. This may be due to differences in parenting styles and family values, or (perhaps more accurately) attributable to the fact that the attachment classifications resulting from the test may reflect a Western bias.

Theories in Action

Ainsworth’s strange situation technique is still used in child development research today. Research on her classifications of secure and insecure attachments has been carried out with older children, adolescents, and adults.


As a teacher, Ainsworth drew a remarkable number of talented graduate and undergrad students into her orbit, many of whom have gone on to make substantial contributions to the field of attachment research themselves—including Sylvia Bell, Mary Blahar, Inge Bretherton, Jude Cassidy, Patricia Crittenden, Alicia Lieberman, Mary Main, Robert Marvin, and Everett Waters, to name just a few.

Ainsworth’s students and colleagues went on to refine her organizations of attachment. After conducting their own longitudinal studies on Bay Area infant-mother dyads, Berkeley professors Mary Main and Judith Solomon added a fourth classification—disorganized/disoriented—to Ainsworth’s original three. The disorganized category, also called class D, represents those infants that have conflicted reactions to their mother (such as reaching out and then pushing away). Disorganized attachment is thought to be a result of maternal behavior that is inconsistent (i.e., sometimes loving, sometimes threatening).

Ainsworth’s students also went on to broaden the field of attachment research in other ways. Marvin performed the first study of attachment in preschoolaged children; Pat Crittenden designed the Preschool Assessment of Attachment (PAA); Main researched the strange situation technique with fathers; Waters developed a Q-sort for home observations; and Blehar did work on attachment and daycare.

Main also developed the Adult Attachment Interview, which asks parents to recall interactions with their own parents. Studies have shown that an infant’s performance on the strange situation test is highly correlated with the parent’s personality and family relationships in childhood as recalled on the AAI.

Other research has studied dimensions of maternal-infant attachment throughout the lifespan. Klaus and Karin Grossman of the University of Regensburg, colleagues and friends of Ainsworth, embarked on a replication study of Ainsworth’s Baltimore project in 1975. Their longitudinal study of mother-infant pairs from Bielefeld, Northern Germany, confirmed many of Ainsworth’s findings, as did a second longitudinal study of Regensburg infants who were followed up on as six-year-olds. The Grossmans also performed follow-up studies on their original Bielefeld children as young adults, analyzing their behavior and language and gathering narrative data on their adult relationships to determine how their early attachments impacted them in the long term.

Interestingly, the Grossman study is most well known for its finding that half of the infants in the sample were classified as “avoidant,” and two-thirds of the infant subjects were insecurely attached. The Grossmans attributed this to the fact that German culture values independence at an early age (see Japanese attachment theory sidebar).

Other noted international psychologists that contributed to attachment theory included the temperament researcher Joan Stevenson-Hinde, Avi Sagi (who studied infant attachment in the communal childcare environment of the kibbutz), and adult attachment researcher Philip Shaver. All consulted with Ainsworth during their career, and she offered her feedback and insights on their attachment research directions.

Another fertile testing ground for attachment research is the University of Minnesota, where researchers embarked on the Parent-Child Interaction Project, a long-term study beginning in 1975 following high-risk (e.g., chaotic home life, low socioeconomic status, no supportive partner) mothers and their infants from birth to adulthood and has contributed a rich body of research on how infant attachment affects relationships later in life. Long-term University of Minnesota studies on these women and their children has found that “anxiously attached” infants frequently grew up to have behavioral and emotional problems, and those that were securely attached had a better quality of social interaction with their peers and better skills at forming friendships, more empathy, and higher self-esteem and self-reliance.

New focuses of attachment research include the development of preventive programs designed to break the intergenerational cycle of insecure attachment by raising parental awareness of attachment issues.

Case Studies

While her early work with Uganda infants described each home setting and mother-infant dyad in detail, Ainsworth took particular care to maintain the confidentiality of her Baltimore study subjects, blinding (i.e., removing names and identifying data and assigning each case with a number for identification purposes) all the data to even her own students. In Patterns of Attachment, Ainsworth describes several Baltimore and Uganda infant reactions to separation from their mother, and how the infants differed in their reactions based on home experience:

[O]ne child in Sample I could not tolerate separation in the strange situation. Throughout the first year he had been left by his working mother with a responsive housekeeper. Until he was about 10 months old, he accepted his mother’s departures in the morning, but then began to protest them. In the strange situation, the moment his mother got up to go at the end of Episode 3 he was undone. Ganda infants … showed more intense distress in everyday separation situations at home than did the American babies of our Sample 1. Most of them had been left with other caregivers every day for four hours or more while their mothers worked in the garden, whereas when the mother was at home she tended to take the baby with her as she moved from room to room. It would seem that when the Ganda mother did leave the baby behind, this signified to him a much longer absence than that expected by most of our American sample babies when the mother left the room. Similarly, we found … that children in full-time day care, having been previously home reared, showed significantly more distress in the separation episodes of the strange situation than home-reared age peers—a finding that may be due to their having become sensitized to separation by their frequent, long absences from home. On the other hand, it would seem likely that these same day-care children might have left the mother’s side voluntarily in order to approach other children when introduced to a new play group, as Ricciuti (1974) found with a sample of young children who had been reared in a daycare center.

Relevance to Modern Readers

Mary Ainsworth’s theories of attachment development have stood the test of time, and researchers still use them as a basis for further research. Today, thanks to the work of attachment pioneers Mary Ainsworth, John Bowlby, and James Robertson, hospitals recognize the importance of letting parents room-in with sick children. Infants that used to be routinely whisked away from their mothers at birth to spend those crucial first days in a hospital nursery are now able to stay in a room with the mother.

The attachment parenting movement also owes a debt of gratitude to Ainsworth and Bowlby. Pediatrician William Sears, who coined the term “Attachment Parenting,” advocates infant care practices such as emotional responsiveness to infant cues, skin-to-skin contact, bed sharing, breastfeeding, avoiding separation, and what Sears calls “babywearing” (i.e., carrying the child everywhere in a body sling).

Complex child development issues such as adoption, foster care, daycare, and grief have been made clearer by the advent of attachment theory. Child service agencies now have a better understanding of how removal from the home impacts attachment processes at different ages. In the United States, long-term foster care is now preferred over group care settings whenever possible. In many places, foster parents receive training on how to be most effective in promoting attachment relationships and how to respond to the foster child’s needs sensitively to become a secure base for the child.