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S
Strange Situation Procedure
(SSP)
Giulia Perasso
University of Milano-Bicocca, Milan, Italy
Synonyms
Ainsworth’s procedure;Attachment assessment
Definition
Mary Ainsworth’s Strange Situation Procedure
(SSP) represents a fundamental breakthrough in
attachment research because it grounded
Bowlby’s attachment theory (Bowlby, 1969)on
empirical evidence (Holmes, 1993). SSP was the
first paradigm allowing developmental psycholo-
gists to classify caregiver-child dyads’attachment
through a 20-min laboratory procedure, overcom-
ing the time length and methodological complex-
ity of longitudinal-ecological observations. SSP
was designed for dyads with the infant aging
between 12 and 18 months and one of his/her
parents, possibly the one being the principal
caregiver.
The Procedure
Ainsworth firstly used SSP in the longitudinal
Baltimore study (Ainsworth & Wittig, 1969;
Ainsworth et al., 1971) and its eight-episode
structure (Table 1) remained unchanged to this
day. Firstly (i) the observer introduces the care-
giver (i.e., commonly the mother) and the infant to
the experiment room, and then he/she leaves; sub-
sequently (ii) the child explores the room while
the mother is passive. If after 2 min the child is not
exploring the surroundings, the caregiver stimu-
lates him/her to pay attention to the environment
and explore it. A stranger (i.e., generally a
woman) enters the room (iii) staying silent for a
minute (first minute) and then speaking with the
mother (second minute) and finally approaching
the infant (third minute). At this point, the mother
leaves the room. The first separation (iv) takes
place with the infant and the stranger together in
the room: now, the stranger orients her attention
toward what the infant is doing. The mother
comes back a few minutes later (v) reuniting
with the infant, greeting and comforting him/her,
and/or engaging him/her in play. Then, the second
separation takes place with the mother leaving the
infant alone in the room (vi). Soon after, the
stranger enters the room once again (vii), gearing
his/her behavior to that of the infant. Conclu-
sively, a second dyad’s reunion (viii) takes place
as the mother returns into the room, greets, and
picks up the infant to comfort him/her, while the
stranger silently leaves.
© Springer Nature Switzerland AG 2023
T. K. Shackelford (ed.), Encyclopedia of Sexual Psychology and Behavior,
https://doi.org/10.1007/978-3-031-08956-5_128-1
In the 1970s, the SSP was conducted in rooms
with a one-way window to allow simultaneous
observation by at least two observers, nowadays
the procedure is filmed and subsequently coded
(Van Rosmalen et al., 2015).
Attachment Patterns
In the first work with the SSP (Ainsworth &
Witting, 1969), the attachment of 14 infants was
analyzed by studying: (a) whether the infant per-
ceived (or not) his/her mother as a secure base
from which to explore a new environment; (b) the
infant’s behavioral responses toward a stranger
(e.g., fear, shyness, and comfortableness) in an
unfamiliar environment; and (c) the behavioral
and emotional reactions of infants in episodes of
separation and reunion with their mothers, in
unfamiliar surroundings. Ainsworth observed the
following behavioral parameters in the infant: the
exploration of the surroundings, gaze orientation,
crying, reactions to the mother leaving and
returning to the room (i.e., responses to being
picked up and put down), and behaviors toward
the stranger. According to these indicators, the
following attachment categories of infants
emerged (Ainsworth & Wittig, 1969; Ainsworth
et al., 1971):
1. Group A (subsequently named “insecure-
avoidant attachment”): infants who did not
appear disturbed by the separation from the
mother and showed great interest in surround-
ings’exploration than maintaining proximity
with the caregiver, without exhibiting fear or
distress toward the stranger.
2. Group B (subsequently named “secure attach-
ment”): infants who were disturbed by the sep-
aration but managed to adapt and explore the
surrounding, exhibiting a moderate response of
distress toward the stranger. These children’s
behavior in the SSP was balanced between
exploration of the environment and proximity
maintenance with the caregiver.
3. Group C (subsequently named “insecure
ambivalent attachment”): infants who
exhibited extreme maladaptive reactions in
the separation/reunion episodes with the
mother, absent or low interest in exploring the
environment, and extreme reactions of fear and
distress toward the stranger. In particular, in the
reunion moments, these children were difficult
to calm down, even when the mother picked
them up for cuddles and reassurance.
Subsequently, Ainsworth’s classification was
expanded by Main and Solomon (1986) who
added a fourth category of infants’attachment
called disorganized/disoriented. Disorganized
infants could not fit in Group A, B, or C, because
SSP observation reveals disruptions of the attach-
ment system (e.g., contradictory behaviors,
incomplete movements, anomalous postures,
freezing, and disorientation) linked to previous
traumatic experiences with the caregiver (Main
& Solomon, 1990).
Conclusion
Even if Ainsworth regretted that SSP has ended up
being more a stand-alone instrument than an
Strange Situation Procedure (SSP), Table 1 The eight episodes of the Strange Situation Procedure (SPSS)
Episode Time length Participants Description
i. 30 s Mother, infant, observer Entering the room
ii. 3 min Mother, infant Infant explores the environment
iii. 3 min Mother, infant, stranger Stranger enters the room
iv. 3 min (approximatively) Infant, stranger First separation
v. 3 min (approximatively) Mother, infant First dyad’s reunion
vi. 3 min (approximatively) Infant Second separation
vii. 3 min (approximatively) Infant, stranger Stranger enters the room
viii. 3 min (approximatively) Mother, infant Second dyad’s reunion
2 Strange Situation Procedure (SSP)
integrative counterpart for ecological home obser-
vations (Ainsworth & Marvin, 1995), nowadays it
is widely considered the principal instrument to
evaluate infants’attachment (Van Rosmalen et al.,
2015). In fact, SSP undoubtedly inspired the
development and validation of other assessment
procedures in attachment research (Van Rosmalen
et al., 2014).
Cross-References
▶Anxious Attachment
▶Attachment Behavioral System (ABS)
▶Attachment Theory/Style: ABC Classification
▶Attachment Theory/Style: Early Childhood
▶Attachment Theory/Style: Internal Working
Models
▶Avoidant Attachment
▶Bowlby, John
▶Child Development: Attachment Style
▶Childhood Abuse/Neglect
▶Emotional Commitment: Attachment Theory
▶Historical Perspectives: Attachment Theory
▶Insecure Attachment
▶Relationship Commitment: Attachment Theory
▶Relationship Attachment Styles
▶Romantic Bonds: Attachment Styles
▶Romantic Relationships, Attachment Theory
▶Secure Attachment
▶Sex Differences: Attachment Theory/Attach-
ment Style
References
Ainsworth, M. D., & Marvin, R. S. (1995). On the shaping
of attachment theory and research: An interview with
Mary DS Ainsworth (Fall 1994). Monographs of the
Society for Research in Child Development, 60,3–21.
Ainsworth, M., & Wittig, D. (1969). Attachment and
exploratory behavior of one-year-olds in a strange sit-
uation. In B. M. Foss (Ed.), Determinants of infant
behavior (Vol. 4). Methuen.
Ainsworth, M. D. S., Bell, S. M., & Stayton, D. J. (1971).
Individual differences in strange-situation behaviour of
one-year-olds. In H. R. Shaffer (Ed.), The origins of
human social relations. Academic.
Bowlby, J. (1969). Attachment. Penguin Publishing.
Holmes, J. (1993). John Bowlby and attachment theory.
Routledge.
Main, M., & Solomon, J. (1986). Discovery of an insecure-
disorganized/disoriented attachment pattern. In T. B.
Brazelton & M. W. Yogman (Eds.), Affective develop-
ment in infancy (pp. 95–124). Ablex Publishing.
Main, M., & Solomon, J. (1990). Procedures for identify-
ing infants as disorganized/disoriented during the Ains-
worth strange situation. In Attachment in the preschool
years: Theory, research, and intervention (Vol. 1,
pp. 121–160). The University of Chicago Press.
Van Rosmalen, L., Van Izjendoorn, M. H., & Bakermans-
Kranenburg, M. (2014). ABC+ D of attachment theory.
In Routledge handbook of attachment: Theory
(pp. 11–30). Routledge.
Van Rosmalen, L., Van der Veer, R., & Van der Horst,
F. (2015). Ainsworth’s strange situation procedure:
The origin of an instrument. Journal of the History of
the Behavioral Sciences, 51(3), 261–284.
Strange Situation Procedure (SSP) 3
