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Mary Ainsworth Strange Situation Experiment

What Is The Strange Situation

The Strange Situation Experiment is a standardized laboratory procedure created in the 1960s by American-Canadia psychologist Mary Ainsworth to identify differences in infant attachment. It measures how a child responds to separations and reunions with the parent to assess the early security of attachment depicted in the Attachment Theory.

The Attachment Theory was originally proposed by John Bowlby in the 1950s.

According to the theory, attachment is an affectional tie an infant forms with their parent.

The hallmark proximity-seeking behavior of attachment is that the child would seek contact and maintain proximity with the attachment figure.

In developmental psychology, an infant’s behavior related to exploration, separation anxiety, stress, and fear of unfamiliarity can predict the child’s attachment style​1​.

These attachment behaviors include proximity-seeking behaviors (such as approaching, following, and clinging) and signaling behavior (such as smiling, crying, and calling).

To examine these patterns of attachment behavior, Ainsworth designed a method carried out in an unfamiliar context.

mother shows toy to infant

The Strange Situation Procedure

In the Strange Situation paradigm, a baby is observed in a room with furniture and toys.

At one end of the experimental room is a child’s chair heaped with and surrounded by toys.

Near the other end of the room, on one side, is a chair for the parent or primary caregiver, and on the opposite side near the door, a chair for the stranger.

Researchers observe the mother-infant interactions in an adjoining room through a one-way mirror.

Mary Ainsworth’s attachment theory test comprises eight strange situation episodes in the following order (mothers were used in the original experiments).

  • Episode 1: Mother and baby are introduced to the room.
  • Episode 2: Mother and baby are alone. The child explores the room freely.
  • Episode 3: Stranger enters the room, talks with the mother, approaches the child, and tries to interact with the child. Mother exits the room after 3 minutes.
  • Episode 4 (First separation): Stranger remains in the room and interacts with the child when needed.
  • Episode 5 (First reunion): Mother re-enters and greets the child in the doorway. Stranger exits.
  • Episode 6 (Second separation): Mother leaves again. Baby is alone for 3 minutes.
  • Episode 7: Stranger re-enters and remains in the room and interacts with the child when needed.
  • Episode 8 (Second reunion): Mother returns and stranger leaves.

Scoring and Classification

An infant’s action was scored based on the following five types of behavior toward the adults.


Proximity-seeking behaviors include active behaviors such as greeting, approaching, clambering up, reaching, or leaning.

Vocal signals such as crying in the adult’s direction are also proximity-seeking.


Proximity-avoiding behaviors usually apply when an adult enters the room or tries to engage the child.

They include ignoring, looking away, turning away, and moving away from the adult.


After the baby has gained contact with the mother, they may show contact-maintaining tendencies.

These behaviors include clinging, embracing, clutching, holding on, and resisting release.

If they lose contact, they turn back and reach, and protest vocally.


Contact-resisting behaviors include angry, ambivalent attempts to push away, hit, or kick the mother who tries to make contact.

The child may squirm to get down when they’re picked up.

They push or throw away toys when the mother tries to interfere with the playing.

Some babies may even scream angrily, throw themselves down, or kick the floor to protest.


Search behavior was evaluated based on the child’s reaction to the mother’s departure.

These actions include following the mother to the door, trying to open the door, banging on it, remaining oriented to the door, glancing at it, going to the mother’s empty chair, or simply looking at it.

Other Behavior

In addition, the child was also observed for the following responses and interactions.

Exploratory (Episodes 2-7)
How much does the child explore with or without the mother’s presence?

Stranger anxiety (Episodes 3, 4, 7)
Does the child seek/avoid or maintain contact with the stranger?

Four Attachment Styles in Infants

The observed response in the Strange Situation procedure has proven to correlate closely with maternal and infant behavior in the home throughout a child’s first year of life​2​.

Initially, Ainsworth classified the nature of the infants’ attachment patterns into three groups​3​.

Later on, the mother-child attachment classifications expanded into four attachment styles as follows.

Insecure Avoidant Attachment (Category A)

Infants with insecure avoidant attachment show no obvious sign of distress during the separation episodes and show avoidance of proximity upon the parent’s reunion.

They don’t seek contact upon the mothers’ return.

If picked up, they show little tendency to cling or resist. Insecure avoidant babies tend to avoid the mother by ignoring her, turning away, moving past, or moving away.

These babies tend to treat the strangers much as they treat their mothers, although with less avoidance.

The caregiver of an avoidant child tends to dislike physical contact with the infant.

The caregiver is generally low in emotional expressiveness, even in response to the sometimes highly aggressive interaction of their infant.

They likely had early experiences of rejection from their parents in their own childhood.

Secure Attachment (Category B)

Mary Ainsworth observed that securely attached infants used the parents as a secure base for exploration when the parents were present.

They explore the novel environment contently when the mother is there.

When the mother of a securely attached baby leaves the room, the baby becomes visibly distressed and cries or searches for her.

Despite the high levels of stress, in Mary Ainsworth’s Strange Situation experiment, infants who were classified as securely attached were more likely to smile and greet the parent happily when the parent returns.

They actively seek contact, comfort, and support.

These babies find comfort in proximity and they can re-establish emotional stability. They then resume exploring the environment.

A child with a secure type of attachment is more interested in interacting with the mother than with the stranger.

Roughly 50-70% of children in the United States have secure attachment​4​.

Infants who are classified as securely attached are more likely to have mothers or caregivers who are sensitive to their signals during feeding, face-to-face play, physical contact, and distress episodes, especially in the first 3 months.

These parents respond promptly and appropriately to the crying early on, resulting in less crying by the time the children reach age one​5​.

Insecure Ambivalent Attachment (Category C)

Insecurely ambivalent infants are very wary of the stranger and highly distressed on separation.

When the parents return, the babies have an ambivalent response.

They show an ambivalent pattern in behavior by seeking close contact and showing angry resistance at the same time.

In the reunion episode, after the mothers’ return, the babies cannot settle and re-establish emotional stability for a long time. They cannot use their parents for emotional regulation.

The caregiver of an ambivalently attached infant show inconsistency in responding to the child’s needs.

Disorganized Attachment (Category D)

An infant’s responses to the parent in the Strange Situation test reflect the history of interaction the child has with that parent at home.

The pattern of these “organized” responses can predict the later functioning of the child.

Attachment research has also found that many children do not fall into any of the above three organized categories.

These kids’ behaviors do not resemble one another in a coherent, organized way.

The only commonalities in their actions are sequences of incoherent reactions that lack a readily observable goal, intention, or explanation.

The diverse, unclassified patterns were disorganized​6​.

Developmental psychologists later on defined this category of attachment in childhood as a disorganized attachment (also known as the disoriented attachment or attachment disorganization)​7​.

The caretaker of a disorganized infant is both the source of fright and the only safe base known to the child.

They are the child’s attachment figure but they also display frightening behavior.

The anomalous parental behavior was due to the unresolved state of mind.

These parents may be abusive, threatening, frightened, or dissociated because of an unresolved loss or their own experience in childhood​8​.

Statistics & Cultural Differences

In Mary Ainsworth’s study with only three categories (A, B & C), she found that the distribution was roughly 60-70% secure, 20% avoidant, and 10-15% resistant attachment.

However, in subsequent studies in other cultures and with other samplings of the population, the distributions were found to be substantially different.

They raised the question that whether cultural differences played a part in child-rearing practices​9​.

However, a meta-analysis of 2000 samples from non-western culture countries found that the global distribution of attachment categorization was consistent with those found previously in the United States.

The differences in studies were caused by variations in socioeconomic status (SES) more than by cross-cultural differences​10​.

Criticism & Alternative Theory

Many studies and research findings have since supported the caregiver sensitivity theory illustrated in the Strange Situation.

However, a meta-analysis including nonclinical samples has found evidence that although parental sensitivity plays a role in determining children’s attachment results, it’s likely not the only condition​11​.

Psychologist Jerome Kagan argued that the individual differences in attachment could result from the diverse infant temperament and their reactions to unfamiliarity, rather than to sensitive parenting​12​.

His point of view is that babies with a “difficult” temperament are likely to have insecure attachments. Child-rearing quality is not necessarily the reason for the child’s attachment type.


  1. 1.
    Ainsworth MDS, Bell SM. Attachment, Exploration, and Separation: Illustrated by the Behavior of One-Year-Olds in a Strange Situation. Child Development. Published online March 1970:49. doi:10.2307/1127388
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    Bretherton I. Attachment Theory: Retrospect and Prospect. Monographs of the Society for Research in Child Development. Published online 1985:3. doi:10.2307/3333824
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    Bowlby J, et. al. Attachment and loss: Retrospect and prospect. American Journal of Orthopsychiatry. Published online October 1982:664-678. doi:10.1111/j.1939-0025.1982.tb01456.x
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    McCabe A, Peterson C, Connors DM. Attachment security and narrative elaboration. International Journal of Behavioral Development. Published online September 2006:398-409. doi:10.1177/0165025406071488
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    Main M, Hesse E. Parents’ unresolved traumatic experiences are related to infant disorganized attachment status: Is frightened and/or frightening parental behavior the linking mechanism. In: Attachment in the Preschool Years: Theory, Research, and Intervention. University of Chicago Press; 1990:161–182.
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    Hertsgaard L, Gunnar M, Erickson MF, Nachmias M. Adrenocortical Responses to the Strange Situation in Infants with Disorganized/Disoriented Attachment Relationships. Child Development. Published online August 1995:1100. doi:10.2307/1131801
  8. 8.
    Schuengel C, Bakermans-Kranenburg MJ, Van IJzendoorn MH. Frightening maternal behavior linking unresolved loss and disorganized infant attachment. Journal of Consulting and Clinical Psychology. Published online 1999:54-63. doi:10.1037/0022-006x.67.1.54
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    Waters E. The Reliability and Stability of Individual Differences in Infant-Mother Attachment. Child Development. Published online June 1978:483. doi:10.2307/1128714
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    van IJzendoorn MH, Kroonenberg PM. Cross-Cultural Patterns of Attachment: A Meta-Analysis of the Strange Situation. Child Development. Published online February 1988:147. doi:10.2307/1130396
  11. 11.
    De Wolff MS, van Ijzendoorn MH. Sensitivity and Attachment: A Meta-Analysis on Parental Antecedents of Infant Attachment. Child Development. Published online August 1997:571-591. doi:10.1111/j.1467-8624.1997.tb04218.x
  12. 12.
    Kagan J. Temperament and the Reactions to Unfamiliarity. Child Development. Published online February 1997:139. doi:10.2307/1131931


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