Research figure: Mary Ainsworth · Written by Artificial Sapiens
How Ainsworth's ABC framework led to Main and Solomon's D classification
Mary Ainsworth and Mary Main occupy successive, closely connected positions in the history of developmental attachment research. Ainsworth helped turn John Bowlby's attachment theory into a program of systematic behavioral observation, establishing the Strange Situation Procedure and the original A/B/C patterns of infant–caregiver attachment. Main, building on that program, investigated behavior that the original patterns could not adequately describe. Working with Judith Solomon, she introduced the disorganized/disoriented (D) classification in 1986 and published a more detailed identification procedure in 1990. Their contribution made visible brief, contradictory, apprehensive, or disoriented behaviors that could interrupt an infant's otherwise identifiable attachment strategy. Duschinsky, 2015; Main and Solomon, 1990.
The historical relationship is foundational: Ainsworth's three organized patterns supplied the observational baseline, while Main and Solomon added a way to code a different dimension of behavior within the same laboratory assessment. A child assigned a D classification may also receive a secondary A, B, or C classification. Accordingly, the later D system cannot be understood simply as one more personality type added to three equally exclusive styles. Its origins and coding logic require attention to the breakdown, conflict, or interruption of an organized attachment response under stress. Duschinsky, 2015; Granqvist et al., 2017.
This article examines that scientific succession: what Ainsworth's work made measurable, what Main and Solomon discovered, how D is identified, what later evidence supports, and where historical classification differs from clinical or popular interpretations. It treats infant attachment as a relationship-specific behavioral research construct, not as a diagnosis or an immutable characteristic of a person.
Intellectual foundations: Bowlby, Ainsworth, and the attachment behavioral system
John Bowlby's attachment theory proposed that infants organize behavior toward familiar caregivers under conditions of threat, fatigue, pain, or uncertainty. Proximity seeking, contact maintenance, signaling, and exploratory activity can be understood in relation to the regulation of felt security. Ainsworth's field research and longitudinal home observations made these propositions empirically tractable. Her earlier intellectual formation also drew on William E. Blatz's security theory, an important historical influence on her understanding of dependence, exploration, and security. These lines of thought informed her distinctive observational account of the caregiver as a secure base. Ainsworth et al., 1978; Bretherton, 1992.
Ainsworth observed caregiver–infant relationships in Uganda during the 1950s and later conducted intensive longitudinal observations of families in Baltimore. Her research documented how young children balanced exploration with movement toward a caregiver, and how reunion behavior provided particularly informative evidence about the organization of an attachment relationship. The Strange Situation emerged from this larger research program rather than as an isolated laboratory test. Its controlled sequence of separations and reunions activated attachment behavior sufficiently to distinguish recurring patterns. Ainsworth and Bell, 1970; Ainsworth et al., 1978.
Historical authorship matters. Barbara A. Wittig coauthored the 1969 chapter introducing the Strange Situation in print. Silvia M. Bell coauthored the 1970 study of attachment, exploration, and separation. The 1978 monograph Patterns of Attachment was written by Mary D. Salter Ainsworth, Mary C. Blehar, Everett Waters, and Sally Wall. It integrated the Baltimore project's procedures and observational classifications; the original first edition was published by Lawrence Erlbaum Associates in 1978. These collaborators are part of the method's documented scholarly history. Ainsworth and Bell, 1970; Ainsworth et al., 1978.
What the original A/B/C patterns meant
Pattern A: avoidant organization
In the original Strange Situation classification, A described a pattern in which an infant tended to minimize overt proximity seeking or contact during reunion, while directing more behavior toward the environment or objects. Apparent calmness should not be equated with an absence of physiological arousal or a lack of an attachment bond. The classification concerns an observed behavioral organization in a particular caregiver–child relationship and specific assessment conditions. Ainsworth et al., 1978.
Pattern B: secure organization
B described infants who could use the caregiver as an effective source of comfort and resume exploration when sufficiently reassured. Some securely classified infants showed considerable distress during separation, while others showed less. Security was therefore inferred from the organization of the full pattern, especially the capacity to seek and use available contact and to recover toward exploration, rather than from how often a child cried. Ainsworth and Bell, 1970; Ainsworth et al., 1978.
Pattern C: resistant or ambivalent organization
C referred to an infant's persistent attachment-system activation, often marked by difficulty settling after reunion, intense contact seeking combined with resistance or anger, and limited return to exploration. This pattern, too, represented an organized strategy within the original theoretical account. It is scientifically misleading to read resistance as mere stubbornness or to assign a child's full personality on the basis of a laboratory reunion. Ainsworth et al., 1978.
The common feature of A, B, and C
The three patterns described relatively coherent, recurrent ways of managing attachment-related stress with a specific caregiver. Their observable behavior differed, but a coder could infer a recognizable organization of attention, approach, contact, avoidance, resistance, and exploration across relevant episodes. This common assumption became the basis of the later scientific problem: what should investigators do when a recording showed striking behavior that could not comfortably be fitted into any one organized pattern? Duschinsky, 2015.
A methodological problem becomes a research program
Mary Main's work developed within the Ainsworth research tradition and extended it into new observational and representational questions. At the University of California, Berkeley, Main studied the development and organization of attachment behavior and later worked with Nancy Kaplan and Jude Cassidy on representations of attachment across infancy, childhood, and adulthood. That research should be distinguished from the adult romantic attachment self-report traditions developed later by other investigators. The 1985 monograph chapter by Main, Kaplan, and Cassidy formed an important part of this developmental expansion. Main, Kaplan, and Cassidy, 1985.
The immediate puzzle involved recordings in which infants displayed conflicted, anomalous, hesitant, or fearful responses to the caregiver that were difficult to express within A, B, or C. A category designed to represent organized behavioral strategies could sometimes obscure the very behavior that demanded explanation. Archival research reconstructs an important period of methodological discussion from 1979 through 1982, including Main's engagement with videos from her laboratory and with recordings supplied by other investigators working with higher-risk samples. Duschinsky, 2015.
Some unusual behaviors were fleeting, lasting only seconds. Others appeared alongside an otherwise recognizable avoidant, secure, or resistant response. Main and Solomon therefore faced a coding challenge: preserve information about the infant's predominant organized pattern while also representing momentary behavior suggestive of conflict or disorientation. The solution eventually produced a new classification and a supplementary code that continued to recognize the original A/B/C patterns. Duschinsky, 2015; Main and Solomon, 1990.
Mary Main and Judith Solomon: the 1986 discovery and 1990 coding procedure
The 1986 chapter by Mary Main and Judith Solomon, "Discovery of an Insecure-Disorganized/Disoriented Attachment Pattern," appeared in the edited volume Affective Development in Infancy. The paper formalized a novel classification of behavior in the Strange Situation. Although the researchers had begun developing the account years earlier, the publication chronology is clear: the 1986 chapter announced D, while the 1990 chapter gave a systematic procedure for identifying disorganized/disoriented infant behavior. The original work belongs jointly to Main and Solomon. Duschinsky, 2015; Main and Solomon, 1986.
Their 1990 chapter, "Procedures for Identifying Infants as Disorganized/Disoriented During the Ainsworth Strange Situation," appeared in Attachment in the Preschool Years, edited by Mark T. Greenberg, Dante Cicchetti, and E. Mark Cummings. Its purpose was to make an otherwise underrecognized set of behaviors available to trained observation, description, and reproducible coding. Main and Solomon described observable indices and a graded decision procedure; they did not propose a psychiatric diagnosis. Main and Solomon, 1990; Granqvist et al., 2017.
The historical evidence also clarifies why the term "disorganized" requires care. Main and Solomon grouped several different outward behaviors because each could suggest a temporary disruption in the coordination of attachment behavior. Different sequences, postures, or moments of apprehension need not share a single immediate cause. The researchers' interest was the operation of an attachment system under strain and the limitations of existing classification, not the assertion that all children placed in D constituted one homogeneous clinical population. Duschinsky, 2015; Duschinsky et al., 2017.
Seven observable indices of disorganization
The 1990 procedure grouped relevant observations into seven broad indices. These are behavioral descriptions intended for trained coders who interpret the infant's complete Strange Situation sequence. Main and Solomon, 1990; Duschinsky et al., 2017.
Contradictory behavior in sequence
An infant may move toward the caregiver or signal a wish for proximity and then abruptly avoid, withdraw, or divert attention in an apparently conflicting sequence. The significance lies in the relationship between the observed actions and the situation in which they occur, rather than in a single movement considered in isolation.
Contradictory behavior at the same time
Simultaneous action tendencies can include approach combined with avoidance or otherwise incompatible postural and behavioral elements. Such observation invites careful description of what actually occurs; it cannot be reduced to the casual impression that the infant is "confused."
Undirected, misdirected, or incomplete movement
An attachment-related action may begin and then break off, or movement may be directed toward an unexpected target. The coder must consider the child's motor development, episode sequence, and whether the behavior plausibly reflects conflict in attachment organization.
Stereotyped, mistimed, or anomalous postures and movements
Some observations involve unusual movements or postures that stand out within the reunion context. Their relevance depends on operational definitions and the larger behavioral pattern, because individual movements can have multiple developmental explanations.
Freezing, stilling, or markedly slowed movement
Brief immobility or marked slowing may be coded when it appears in a context consistent with the protocol. Freezing is an observable behavior, and the precise psychological mechanism behind it remains an inference requiring appropriate evidence.
Apprehension directed toward the caregiver
The infant may display behavior consistent with apprehension of the very adult normally approached for comfort. This index has been central to later hypotheses about fear and caregiving. Nevertheless, a D classification by itself does not identify the cause of such apprehension or establish abuse. Granqvist et al., 2017.
Overt disorientation
Behavior may show a transient disruption of orientation or of apparently goal-directed engagement with the environment. Coding requires the full context, including age-appropriate expectations and the sequence of episodes, rather than an everyday interpretation of a momentary expression.
These indices are not interchangeable symptoms of a disorder. The coding system also distinguishes between conspicuous behaviors that may independently warrant a D decision and less decisive observations whose cumulative pattern must be weighed. Reliable research application requires training, full video records, coding procedures, and attention to interrater reliability. Duschinsky et al., 2017.
The special importance of reunion behavior
Ainsworth's laboratory procedure used planned separations and reunions to elicit individual differences in attachment behavior. Main and Solomon retained this procedural foundation. Behavior during reunion was often especially informative because the infant had renewed access to a caregiver at precisely the moment the attachment system might have been activated by the separation. Contradictory approach and avoidance, hesitations, unusual postures, or apprehension could become more visible at that point. Ainsworth et al., 1978; Duschinsky, 2015.
Nevertheless, disorganized or disoriented behaviors may also be observed during other episodes. A sound historical description should therefore avoid the simplified claim that D is assigned solely from what happens on the final reunion. The measurement depends on the full observation and on standardized criteria, including the degree, type, and contextual meaning of unusual behavior. Duschinsky, 2015.
Why a D classification can coexist with A, B, or C
One of the most important aspects of the conceptual transition is the distinction between a primary D classification and an underlying, or secondary, organized classification. An infant may predominantly show a recognizable secure, avoidant, or resistant organization while also displaying behavior that meets the criterion for disorganization. Consequently, coding D does not mean the original organized classification disappears or that the infant has no attachment strategy at any time. Duschinsky, 2015.
The resulting system allowed researchers to describe interruptions or conflicts in organized behavior without discarding the useful distinctions originally developed by Ainsworth. It also reduced the methodological pressure to force unusual recordings into A/B/C alone. In this respect, Main and Solomon's contribution simultaneously extended and refined Ainsworth's framework. The distinction remains important when comparing research that reports four broad distribution categories with studies that preserve more detailed primary and secondary codes. Duschinsky et al., 2017.
A label in a statistical table can hide this complexity. Published summaries often list secure, avoidant, resistant, and disorganized as four mutually exclusive reporting groups. That practical presentation is not equivalent to the proposition that D was originally devised as one more organized strategy identical in kind to A, B, and C. Interpreting the data responsibly requires understanding the measurement structure behind the table.
Theoretical interpretations: conflict, fear, and behavioral organization
The idea of organized attachment behavior helps explain why contradictory or interrupted behavior drew attention. Attachment-related responses coordinate attention, movement, proximity, and exploration around the availability of protection. If approach toward the caregiver becomes associated with apprehension or conflicting action tendencies, ordinary goal-directed sequences may be interrupted. Such an account provides a theoretical interpretation of the observed behavior; it is not a direct reading of a child's internal experience. Duschinsky, 2015.
Subsequent work by Mary Main and Erik Hesse explored the hypothesis that frightened or frightening caregiver behavior may place an infant in a conflict between approaching a caregiver for security and reacting to that caregiver as a source of alarm. This proposal shaped later research on caregiving and disorganization. It should be presented as a mechanism supported in part by observational associations and theoretical development, with room for other pathways and contextual explanations. Main and Hesse's hypothesis does not establish that every D-coded infant experienced maltreatment or was frightened by the caregiver in the same way. Granqvist et al., 2017.
Other contributors extended work on atypical caregiving, disrupted communication, and developmental adaptation, including Karlen Lyons-Ruth and colleagues. The larger literature points to multiple pathways, contextual risks, and meaningful variation between children and caregiving relationships. It is therefore useful to distinguish the observed D behaviors from hypotheses about their origins and from later mental-health outcomes. Those three levels are related through research but require separate evidence. Duschinsky et al., 2017; Granqvist et al., 2017.
Later empirical evidence: prevalence and variation
The international meta-analysis by Madigan and colleagues (2023) assembled more than 285 Strange Situation studies comprising 20,720 child–caregiver dyads. Its pooled classifications were approximately 51.6% secure, 14.7% avoidant, 10.2% resistant, and 23.5% disorganized. These are aggregate estimates across particular research samples, periods, and settings, not probabilities that apply mechanically to every country, population, or individual child. The evidence also documented variation by region and sample risk profile. Madigan et al., 2023.
These results support the enduring usefulness of an observational system encompassing both Ainsworth's original categories and the later D classification. At the same time, they illustrate that a distribution depends on the composition of the sampled populations, the measurement protocol, coder practice, and historical context. The meta-analysis reported higher disorganized classifications in several higher-risk contexts, including samples affected by maltreatment or certain adverse caregiving circumstances. Group-level associations cannot determine the history of a specific family from a classification alone. Madigan et al., 2023.
A prior meta-analysis by van IJzendoorn, Schuengel, and Bakermans-Kranenburg (1999) examined precursors, correlates, and developmental sequelae of infant disorganization. Its value lies in integrating early cumulative evidence rather than making the construct clinically self-evident. It remains important to compare early findings against larger subsequent syntheses and against improved understanding of the diversity of observational indices. van IJzendoorn et al., 1999.
Developmental prediction: elevated risk is not destiny
Research has found an average association between attachment insecurity or disorganization and certain later developmental difficulties, while effect sizes and explanatory pathways vary. Fearon and colleagues' meta-analysis of 69 samples with 5,947 participants found an association of infant disorganization with later externalizing behavior, with an average standardized effect of about d = 0.34 for the disorganized group. This is a population-level risk association, not an individual prognosis, a causal proof, or an inevitable outcome. Fearon et al., 2010.
Development is affected by ongoing caregiver relationships, changes in family resources, child development, stress exposure, and subsequent support. A D classification can be informative to a research program investigating developmental pathways, but it cannot validly establish a lifetime personality structure or predict a particular psychiatric disorder in a given infant. The expert synthesis by Granqvist and colleagues explicitly cautions against using D as a fixed trait or a definitive forensic assessment. Granqvist et al., 2017.
Clinical and child-protection interpretation
Infant attachment classification is an observational research construct describing a specific child–caregiver relationship in a defined assessment. It differs from a psychiatric diagnosis, an attachment disorder, an autism assessment, a trauma diagnosis, and general developmental screening. Disorganized attachment also differs from clinically defined reactive attachment disorder and disinhibited social engagement disorder. These concepts have different diagnostic criteria, purposes, and evidentiary requirements. Granqvist et al., 2017.
A caregiver–child Strange Situation outcome cannot serve as a stand-alone determination of child maltreatment. Some maltreated samples have elevated group prevalence of disorganization, yet many D-coded children have not been shown to be maltreated and some maltreated children are assigned other classifications. The 2017 multidisciplinary consensus cautions against converting an observational code into evidence sufficient for custody or protection decisions. Decisions with major consequences require independent, context-specific assessments by appropriately qualified professionals and consideration of multiple forms of information. Granqvist et al., 2017.
Descriptions such as "the child is disorganized" can also obscure the relationship-specific and developmental nature of the observation. More accurate terminology states that a child–caregiver dyad received a disorganized/disoriented classification in a specified observational procedure. This usage preserves what researchers actually measured and protects against overgeneralizing an assessment to every relationship in the child's life.
Cultural context and methodological limits
The Strange Situation was developed within specific historical research settings, including Ainsworth's Baltimore observations, and is used in many countries. Broad replication demonstrates its research influence, but cultural expectations concerning separation, proximity, caregiver availability, unfamiliar adults, and the organization of everyday care can affect how infants respond to laboratory stress. Cross-cultural use therefore requires attention to ecological validity, local caregiving practices, calibration, and the interpretation of observed patterns. Madigan et al., 2023.
Methodological care is especially important for D because some indices involve brief and heterogeneous actions. A coder must distinguish behavior relevant to the attachment system from differences related to motor development, health, environmental conditions, ordinary hesitation, or unusual but noninformative movements. Expert training, reliability checks, complete recorded episodes, and cautious inference are essential. Scholars have also debated the conceptual unity of the different D indices and the relation between observable behavior and inferred mechanism. Duschinsky et al., 2017.
Differences in research populations create additional challenges. A sample recruited for clinical or child-protection concerns cannot be assumed comparable with a low-risk community sample. Pooled estimates are useful summaries of a heterogeneous literature, while precise research design remains central to interpreting each result. These points support developmentally and culturally informed science rather than a universal, context-free reading of the same behaviors.
Historical continuity and scholarly attribution
The progression from Ainsworth to Main and Solomon illustrates a productive pattern of scientific change: a measurement system establishes recognizable regularities, and later investigators find observations for which its initial categories are insufficient. Ainsworth's secure-base observations and laboratory classifications created the baseline. Main and Solomon's work clarified what the baseline left underdescribed, helping attachment research accommodate momentary breakdowns of strategy, not merely differences between organized strategies. Duschinsky, 2015.
The change involved a network of researchers. Bowlby's attachment theory preceded Ainsworth's empirical refinements; Blatz's security theory was an earlier formative influence; Wittig and Bell were coauthors of foundational Strange Situation publications; Blehar, Waters, and Wall coauthored the 1978 Patterns of Attachment monograph. Later, Main's collaborations with Kaplan, Cassidy, Hesse, and especially Solomon helped transform the scope of the research program. Retaining those names makes it possible to distinguish intellectual ancestry, methodological collaboration, and the original authorship of the D classification.
The A/B/C and D research programs remain closely connected in method but different in historical authorship and theoretical purpose. The transition from one to the other is therefore best understood as a scientific extension of a successful observational instrument. Modern meta-analytic evidence confirms continuing research application; present-day clinical safeguards clarify the limits of what the classifications can establish. Madigan et al., 2023; Granqvist et al., 2017.
Frequently asked questions
Did Mary Ainsworth discover disorganized attachment?
Mary Ainsworth established the original A/B/C attachment classification system within her research program. Mary Main and Judith Solomon introduced the later disorganized/disoriented D classification in their 1986 publication and articulated its observation and coding procedure in 1990. The D classification belongs historically to Main and Solomon. Duschinsky, 2015.
Is disorganized attachment a fourth attachment style?
In many research summaries, D is reported alongside A, B, and C as a fourth broad classification. The original measurement logic is more precise: D codes anomalous or conflicting behavior that can coexist with an identifiable secondary A/B/C pattern. It is useful to retain that distinction rather than equate D with an organized style of the same kind. Duschinsky et al., 2017.
Can D be identified from a single behavior at home?
The formal classification requires trained coding and the relevant standardized assessment context. An unusual gesture, brief stillness, or contradictory movement at home cannot independently establish an attachment classification. Interpretation depends on the entire behavioral sequence, its context, and appropriate coding standards. Main and Solomon, 1990.
Does D mean a child was abused or will have a disorder?
D is associated with certain risks at the group level but does not demonstrate maltreatment and cannot predict an individual disorder. Expert consensus explicitly rejects using disorganization as a definitive marker of abuse, permanent pathology, or an unchangeable child trait. Granqvist et al., 2017.
Are adult romantic attachment styles the same as infant ABCD classifications?
Adult romantic attachment research uses partly different constructs, measurement approaches, and populations. The Strange Situation classifies observed infant–caregiver relationship behavior, while many adult romantic attachment measures assess self-reported relationship expectations such as anxiety and avoidance. The historical systems are related in theoretical ancestry but must not be treated as interchangeable measurements. Main, Kaplan, and Cassidy, 1985.
Related Articles
Mary Ainsworth — A comprehensive account of Ainsworth's intellectual formation, original observations, publications, and role in developmental attachment research.
Attachment in Infancy and Early Childhood: Security and Development — The developmental context for early attachment, caregiver relationships, and research on security.
Mary Ainsworth's Attachment Classifications: Secure, Avoidant, and Resistant
Mary Ainsworth's Strange Situation Procedure: Design, Episodes, and Interpretation
Mary Ainsworth's Scientific Legacy: Evidence, Limitations, and Influence
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