A preview of this full-text is provided by American Psychological Association.
Content available from Psychological Bulletin
This content is subject to copyright. Terms and conditions apply.
The First 20,000 Strange Situation Procedures:
A Meta-Analytic Review
Sheri Madigan
1, 2
, R. M. Pasco Fearon
3
, Marinus H. van IJzendoorn
4, 5
, Robbie Duschinsky
6
,
Carlo Schuengel
7
, Marian J. Bakermans-Kranenburg
8
, Anh Ly
1
, Jessica E. Cooke
1, 2
,
Audrey-Ann Deneault
1, 2
, Mirjam Oosterman
7
, and Marije L. Verhage
7
1
Department of Psychology, University of Calgary
2
Alberta Children’s Hospital Research Institute
3
Centre for Family Research, Department of Psychology, University of Cambridge
4
Research Department of Clinical, Education and Health Psychology, University College London
5
Faculty of Medicine Nursing and Health Sciences, Monash University
6
Primary Care Unit, Department of Public Health and Primary Care, University of Cambridge
7
Clinical Child and Family Studies, Vrije Universiteit Amsterdam
8
Institute of Psychological, Social and Life Sciences, ISPA University
The Strange Situation Procedure (SSP) was developed five decades ago to assess infant–parent attachment
relationships. Although the procedure itself has remained relatively constant in over 285 studies (20,720
dyads) conducted to date, there have been vast sociological changes during this time, and research foci shifts
to studying diverse populations. Since its inception, the SSP has also been adopted in over 20 countries. In
this meta-analysis, we collate this large body of work, with the objectives of producing reliable estimates of
the distribution of the four SSP attachment classifications, assessing temporal trends and geographical
differences, and determining if and when distributions are different across various populations. Results
revealed that the global distribution of SSP attachment was 51.6% secure, 14.7% avoidant, 10.2% resistant,
and 23.5% disorganized. There were no differences in the distribution among mothers and fathers, and no
child age or sex differences. We found a temporal trend in which there was less avoidant attachment over
time and there were attachment distribution differences between samples from North America versus other
regions of the world, particularly Asia, Middle East/Israel and South America. We found higher rates of
avoidant and disorganized attachment in populations with sociodemographic risks and higher rates of
disorganized attachment in samples where parents had psychopathology and when the child experienced
maltreatment or was adopted from foster or institutional care. The implications of these findings for future
research and practice are discussed.
Public Significance Statement
This meta-analysis suggests that, worldwide, one in every two infants develops a secure attachment
relationship with their caregiver. Secure attachment is more likely to develop when fewer stressors are
imposed on the parent–infant dyad.
Keywords: strange situation procedure, infant attachment, parent–infant relationships
Supplemental materials: https://doi.org/10.1037/bul0000388.supp
The Strange Situation Procedure (SSP), first introduced by Ains-
worth and Wittig in 1969, has been one of the most widely used and
relied upon paradigms in child development research over the last
half-century. The SSP is a 21-min observational procedure that
involves two separations and reunions between an infant and their
parent or other caregiver. It assesses individual differences in
attachment behavior by presenting mild cues to danger (i.e., pres-
ence of a stranger; separation from a caregiver) in a seminaturalistic
but standardized context, which are expected to activate the “attach-
ment system.”These differences in attachment behavior are thought
This document is copyrighted by the American Psychological Association or one of its allied publishers.
This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Sheri Madigan https://orcid.org/0000-0002-7536-3258
The authors Sheri Madigan and R. M. Pasco Fearon share first authorship.
The authors acknowledge Cheri Nickel, Masters in Library and Informa-
tion Science (University of Calgary), for conducting the literature search for
this project.
Codebooks and scripts relevant to this submission can be found here at
https://osf.io/fr4e5/?view_only=2f1e35e7bebc4d28b12691a9d1a0ece4.The
data approach adopted the hierarchical linear modeling framework for
meta-analysis, in which individual data points are nested within studies.
This review was not preregistered.
Correspondence concerning this article should be addressed to Sheri
Madigan, Department of Psychology, University of Calgary, 2500 University
Avenue, Calgary, AB T2N 1N4, Canada. Email: sheri.madigan@ucalgary.ca
Psychological Bulletin
© 2023 American Psychological Association 2023, Vol. 149, Nos. 1–2, 99–132
ISSN: 0033-2909 https://doi.org/10.1037/bul0000388
99