To Francisca


About the Author

Frank C.P. van der Horst was born on August 5, 1977 in Delft, the Netherlands. He obtained a Master’s in History and one in Education and Child Studies from Leiden University and was offered the chance to do research on a crossroads of both disciplines. Under the supervision of Professors Van der Veer and Van IJzendoorn – both notable experts in the field – he expanded on the historical and theoretical work at the Centre for Child and Family Studies at Leiden University and focused on the cross-fertilization of ethology and attachment theory, resulting in his Ph.D. thesis John Bowlby and ethology: A study of cross-fertilization. During this project, he discovered many hitherto unknown data in private and public archives and used oral histories to relate the historical development of John Bowlby’s ideas.

Currently, Van der Horst works as a psychologist at De Waag Rotterdam, an outpatient clinic for forensic psychiatry, and as a researcher at the Centre for Child and Family Studies, Leiden University. His research aims at describing the history of ideas in the behavioral sciences, such as the ideas and work of John Bowlby, René Spitz, William Goldfarb, Jean Piaget, and Harry Harlow. His aim is also to further unravel the roots of attachment theory in, for example, the work of James Robertson and that of developmental psychologist Mary Ainsworth. These studies are necessary to complete our picture of the historical embeddedness of theoretical innovations in developmental psychology.


by Professor Jerome Kagan

A question guaranteed to pique the interest of scientists and non-scientists asks, for each phenomenon, to what degree was this event constrained by its past and, therefore, potentially predictable? That is why millions of viewers will watch documentaries describing the origin of our universe or the evolution of life forms. The imprint of the past on the present assumes a special significance when we ask why some adults believe they are less happy than their friends. Economists and political scientists who gather questionnaire evidence from adults in varied societies report that extreme poverty and serious illness are a major cause of unhappiness. Philosophers, on the other hand, argue that a failure to honor one’s ethical standards is the enemy of continued serenity or joy. A reasonable proportion of biologists and psychologists share the belief held by Alice James, the younger sister of William and Henry James, that a sanguine or melancholic mood is due, in part, to one’s genes.

The strong claim that the experiences of early childhood make a major contribution to adult moods, and by inference quality of adaptation, is relatively recent in the history of ideas. This notion began to gain credence in Europe during the eighteenth century after the size of the middle class had grown and many mothers could stay at home rather than work in the field or at a loom. As a result, society needed to find a critical function for these women and influential commentators nominated a mother’s love for her child as the elixir necessary for healthy psychological development. A large proportion of contemporary psychiatrists and psychologists are certain that the quality of the infant’s emotional relationship with its primary caretaker, preferably the biological mother, affected the probability that the adult will or will not be vulnerable to frequent bouts of anxiety or depression.

John Bowlby tweaked consensual opinion when he replaced the infant’s need for the sensory pleasures accompanying feeding, which Freud had nominated as formative, with the more psychological need for a feeling of security that a loving mother provides. Bowlby’s childhood may have prepared him for this hypothesis. As the fourth child in an upper-middle-class, English family whose care was entrusted to nursemaids who tended the young Bowlby and his siblings in rooms on the top floor of the family’s spacious home, Bowlby recalled seeing his mother for about an hour a day and his father once a week. In addition, his favorite nurse left the household when Bowlby was only four years old. Bowlby spent a long, productive career trying to prove that the quality of the interaction between the mother and infant constrained the child’s future in a serious way.

Frank van der Horst’s beautifully crafted, even-handed history of the 50-year interval between Bowlby’s intuition that infants deprived of maternal love were at risk for an unhappy life and Mary Ainsworth’s 1978 volume, Patterns of Attachment, provides readers with a trail of facts so rich in detail each can decide on the validity of Bowlby’s bold idea.

The Bowlby narrative can be divided into four relatively discrete stages. The first centers around Bowlby’s brief employment at one of the many progressive schools established in the 1920s as an educational application of Freud’s ideas. Most of the children attending this school were emotionally disturbed and some had experienced early separation from parents or obvious neglect. Bowlby regarded these facts as supporting the writings of Ian Suttie, with whom Bowlby was familiar, arguing that a mother’s love for the child was as vital for its psychological development as good nutrition was for its physical growth.

The second stage began in 1946 when Bowlby joined the staff of the Tavistock Clinic where he met James Robertson, a social worker, who shared Bowlby’s distress over the policy of hospitals forbidding mothers from visiting their young children hospitalized for surgery because the staff wanted to prevent the mothers from bringing infections into the ward. Robertson’s 1952 film, A Two-Year-Old Goes to Hospital, had an emotional impact on audiences far greater than either Bowlby or Robertson had anticipated. I showed this film for several years to large undergraduate classes at Harvard and always noted tears flowing down the faces of the stunned audiences when the film ended.

Van der Horst documents the significance of Bowlby’s reading of the ethological research of Lorenz, Tinbergen, and Hinde and the fruitful collaboration with the American psychologist Harry Harlow. Harlow’s experiments on rhesus monkeys, which implied that the opportunity to cling to something soft was more critical than food in establishing a bond to a surrogate object, and the ethological investigations allowed Bowlby to detect the relevance of the concept of a releaser and the reactions it evoked. He applied these ideas to the mother–infant relationship by arguing that the face, hair, and hands of the mother acted as releasers for the infant’s grasping, clinging, smiling, and babbling which, through their implementation, established an attachment bond between infant and caretaker. Bowlby regarded the attachment process as analogous to the imprinting of newly hatched goslings which follow the first moving object they see.

Mary Ainsworth’s research in Uganda and her invention of the Strange Situation at Johns Hopkins University represent the final stage in Van der Horst’s reconstruction. Ainsworth joined Bowlby’s staff at the Tavistock because her husband decided to work in London for a short period and she needed a job. Ainsworth had been mentored by William Blatz at the University of Toronto and the latter shared Bowlby’s conviction that the infant’s security was critical for healthy development. Hence, Ainsworth came to Bowlby prepared to share his fundamental premises. She began to develop her ideas systematically after spending 1954–55 in Uganda observing 28 Ganda infants. This experience led her to posit the three categories of secure attachment, insecure attachment, and non-attachment. Ainsworth acknowledged in the 1967 book Infancy in Uganda that the infant’s temperament can influence the mother–child relationship and she wrote, “We must concede that there are genetically based individual differences between babies … It is quite impossible to differentiate genetic, prenatal, and perinatal influences from environmental influences” (p. 387).

Ainsworth described one infant she had classified as non-attached because the girl did not cry or attempt to follow the mother when she left the room, even though this child struck her as happy and comfortable. I suspect this girl belonged to the temperamental group my colleagues and I call low-reactive. Ainsworth also described a small group of infants classified as insecurely attached because they cried frequently – this is category she would later call type C, insecure-resistant. Ainsworth had noticed that these children were chronically fussy babies who cried not only when their mother left them, but also when they were held by the mother. Always a careful observer, Ainsworth informs readers that two of these infants were chronically malnourished. Crying because of hunger should not be equated with crying because of an insecure attachment. In a telling sentence toward the end of the book Ainsworth suggested, “Therefore, the warmth of the mother and her observed affectionate contact behavior do not explain the differences between groups” (p. 394), and she later adds, “There is no evidence that care by several people necessarily interferes with the development of healthy attachment” (p. 395).

However, Ainsworth and her three colleagues failed to mention the role of temperament when they summarized the results of the study of Baltimore infants in Patterns of Attachment. This investigation, based on extensive observations of a small group of infants at home over the course of the first year and their reactions in the Strange Situation at one year, was the origin of the currently popular attachment categories called type B, securely attached, and types A and C, insecurely attached.

The events of these four stages came together like a perfect storm in the Bowlby and Ainsworth volumes to raise the consciousness of Americans and Europeans to the possibly dangerous consequences of an infant’s insecure attachment to its parents. Historians will praise Van der Horst for a critically neutral narrative, free of the author’s prejudices, that allows each reader to judge the validity of the Bowlby–Ainsworth inferences.

Nonetheless, it is possible to discern beneath the surface of the seamless prose the possible effects of the historical context in which Bowlby formed his ideas. Wise commentators on human nature have been brooding on the causes of human unhappiness for a long time. Because assigning significance to a mother who failed to be sensitive to her infant’s need for security did not emerge as an explanation until the twentieth century, it is appropriate to speculate that the unique pattern of conditions during the last century that made quality of attachment an attractive explanatory concept. The changes in the family during the twentieth century were discontinuous with the form that dominated Europe and North America during the prior two centuries. Young mothers began to enter the work force in large numbers after 1945 and needed surrogate care for their young children. This disruption in the usual form of infant care worried many citizens who automatically assumed that this novel arrangement probably had malevolent consequences. Richard Kearsley, Philip Zelazo, and I shared that belief in the late 1970s when we studied the effect of day care on Boston infants during their first 29 months.

It is also relevant that the first half of the last century was marked by two destructive wars, the horrors of the Holocaust, an undisguised challenge to the concept of God (a Time magazine cover during this period declared, “God is Dead”), increased geographic mobility, and erosion in the moral authority of traditional elites. It is reasonable to assume that this blizzard of events provoked bouts of uncertainty in many adults who naturally searched for an explanation of their cognitive dissonance. Because Americans and Europeans regard the results of scientific research as providing the most reliable access to correct explanations, and Western scientists typically look to distant origins to account for the present, it was easy to be persuaded by statements from respected scientists that the causes of the contemporary angst lay in the events of early childhood. I suspect, however, that this explanation had its roots in the insecurity of the adults who projected their mood on to the young child. Some nineteenth-century scholars were convinced that the origin of adult greed could be seen in the newborn’s reflex grasping of a pencil placed in the palm. If middle-class adults from the majority ethnic and religious groups in their society, who suffered neither extreme poverty nor bigotry, believe that their current tensions and anxieties are due, in part, to their infant experiences, most will be able to retrieve enough evidence to construct an explanation that places some of the blame on their parents. Equally unhappy African-American and Hispanic-American adults who were raised in poverty in urban ghettoes usually blame their mood on their society not their mothers.

The evidence does indicate that serious neglect or abuse of infants can have undesirable effects on their future psychological development. No one quarrels with that opinion. But the vast majority of infants escape these real threats to psychological growth. It is less obvious that the normal variation in maternal sensitivity to infants has the power to constrain the future indefinitely, unless adults, reflecting on their childhoods, decide that they should have had more loving care than they believe they received. Millions of Chinese infants born during Mao Zedong’s reign rarely saw their parents and spent most of their days in day care centers with many infants and few caretakers. But I know of no evidence suggesting that the 50- to 70-year-olds currently living in the People’s Republic of China, who spent their early years in these centers, are significantly more anxious, depressed, addicted, or incarcerated than the generations born 30 years earlier or later. Indeed, today’s headlines imply that feelings of insecurity may be more salient today in a capitalist China with a one child policy and fewer day care centers than in the China of the 1960s.

This foreword is not the place to review the extensive evidence bearing on the validity of Bowlby’s hypothesis and the child’s behavior in the Strange Situation. However, it is fair to suggest that the available evidence neither proves nor refutes Bowlby’s creative synthesis with certainty. The existing data are simply inadequate for a consensus on these questions and, therefore, impossible to decide whether we should reject or accept these ideas. But no matter what future research reveals, scientists, parents, and other citizens will profit from Van der Horst’s coherent, gracefully written, even-handed, and richly detailed description of how these important ideas rose to a position of prominence.


The present book is the fruit of my work at the Centre for Child and Family Studies, Leiden University, the Netherlands, between 2004 and 2010. During these years, I was guided by Professor René van der Veer, whom I consider my scientific mentor. His warm-hearted, enthusiastic, and humane support was of immeasurable importance to the outcome of my scientific work. I am grateful to him for keeping up with my ignorance.

The many discussions with René – back and forth from our offices to the coffee machine – have contributed much to the result that lies in front of you. On the basis of a rough estimation of the distance we covered, I calculated that during these discussions, we walked from Leiden to Paris, and back. During this trip to the City of Light we consumed several thousands cups of coffee. I am very thankful that we were spared from both blisters and ulcers.

Over the years, many people have contributed to my research on the roots of attachment theory. I am particularly indebted to Inge Bretherton for reading and extensively commenting on earlier drafts of this book. Her knowledgeability with respect to the history of attachment theory is unprecedented. Several people were willing to be interviewed on the cross-fertilization of attachment theory and ethology: Inge Bretherton, Robert Hinde, Joan Stevenson-Hinde, Helen LeRoy, Howard Steele, Stephen Suomi, and Everett Waters. I thank Marinus van IJzendoorn for his suggestions and comments to several chapters in this book. René van der Veer was of immense help and corrected many errors and inconsistencies in the text. For those flaws that remain, I am fully and solely responsible.

For permission to use photographs in this book, I thank Mary Gatling, Helen LeRoy, Hillary Wakefield, and Mirrorpix. Parts of this book have been published in journal articles in the past few years. I am grateful for the publishers of these journals (American Psychological Association, John Wiley & Sons Ltd., Routledge, and Springer) for their permission to use parts of the articles in this book. As the saying goes ‘the whole is greater than the sum of its parts’: by compiling the insights from these different papers, a better and richer picture of Bowlby’s move from psychoanalysis to ethology will be painted.

Frank van der Horst
Leiden, April 2010


In the late 1950s and early 1960s, British child psychiatrist John Bowlby in a series of six papers (Bowlby, 1958d, 1960a, 1960b, 1961a, 1961b, 1963a), basically formulated what is now known as “attachment theory.” He later elaborated his ideas in his trilogy Attachment and Loss (Bowlby, 1969/1982b, 1973, 1980a). Attachment theory, in which Bowlby tried to explain how and why children form bonds with their parents and caregivers, has been influential ever since its initial formulation.

Bowlby’s theorizing on the mother–child relationship was the ultimate result of his interest in issues of separation. In her description of Bowlby’s early life, Van Dijken (1998) has shown that the roots of this interest lie in his own early childhood, in experiences while working as a volunteer in several progressive schools, and in clinical observations when he was training as a psychoanalyst shortly before World War II. Bowlby was shaped by the psychoanalytic training he received from his supervisors Joan Riviere and Melanie Klein,but he differed with them about the influence of internal andexternal factors on child development and clinical problems. Bowlby’s focus was more on observation of real-life events and experimentation, while Klein emphasized “research limited to analytic sessions” (Bowlby, 1940a, p. 154) and unconscious fantasies as the origin of psychopathology. As a result of this theoretical disagreement, Bowlby’s position within the British Psycho-Analytical Society was at a certain point in time rather precarious (Van der Horst, Van der Veer and Van IJzendoorn, 2007; Van Dijken et al., 1998). But by ignoring what he considered to be the limited views of some of his psychoanalytic colleagues and taking an eclectic approach instead, Bowlby arrived at new and revolutionary insights. In Van Dijken’s study (1998), she concluded that “by combining and synthesizing thevarious viewpoints he accepted, Bowlby gradually developed his own view,” a view that “was enriched by ethological insights and by Ainsworth’s contribution” (p. 161).

In this study, I will build on Van Dijken’s findings and describe both the “ethological insights” that enriched Bowlby’s view on the mother–child relationship, i.e., how Bowlby turned from psychoanalysis to ethology as a frame of reference, and Mary Ainsworth’s contribution to attachment theory. The focus of this book, therefore, is the historical development of attachment theory between 1951 and 1969. The year 1951 marks the publication of Bowlby’s (1951, 1952) WHO report on Maternal Care and Mental Health, a study which was of immense importance to Bowlby’s thinking. Also, 1951 is the year Bowlby got acquainted with ethology, which I will argue is an Archimedean point in the history of attachment theory. Finally, 1951 is the year Ainsworth applied for a job at the Tavistock Clinic. In 1969, of course, the first part of Bowlby’s trilogy was published. If we consider the pre-1951 period as the psychoanalytic phase of John Bowlby’s career, then the period between 1951 and 1969 can perhaps best be defined as the “ethological era of attachment theory.”

Although the historiography on Bowlby’s ideas has grown rapidly in the last two decades – alongside the ever-growing interest in the clinical applications of attachment theory – so far this episode in the history of attachment theory has received little attention. In the available historical accounts, Bowlby’s life and work have been described from different angles. For example, Bretherton (1991, 1992) mentions some of the highpoints of the ethological period, but her article is an account of Bowlby’s and Ainsworth’s joint contributions to attachment theory, with emphasis on its roots and growing points. Newcombe and Lerner (1982) paid attention to the historical and societal context in which Bowlby developed his ideas. Mayhew (2006) described Bowlby’s political activities in relation to his theoretical ideas. Holmes (1993) contributed to the historiography of attachment theory by describing the implications of Bowlby’s ideas for clinical practice, while Karen (1994) added new biographical information. Van Dijken (1998) has traced the core of attachment theory to Bowlby’s early childhood and advanced the thesis that early separation experiences influenced his further development and thinking. However, until now, no systematic and detailed analysis of Bowlby’s (and Ainsworth’s) use of the new science of ethology has been made.

Because this crucial period cannot be dealt with as an isolated story, I will start with a comprehensive description of Bowlby’s early life and career (see Chapter 1). I will try to show that Bowlby’s intellectual development and his turning toward ethological methods were not coincidental. His focus on separation as a subject of research, his valuing of children’s real-life experiences for further personality development, his emphasis on observation, and his interest in nature and the emerging science of ethology, were certainly part of a historical development, as will become clear from his biography.

In Chapter 2, I will discuss the different issues of separation of young children that Bowlby encountered during the late 1930s, the 1940s, and the early 1950s. These issues include separation due to wartime evacuations, observations made in residential nurseries, the debate concerning visiting of children in hospital, results of clinical studies, and studies on the so-called “hospitalization” effect. The results of these studies and observations were the core of Bowlby’s WHO publication and convinced him of the importance of early-life experiences for child development.

This description of the issues of separations and the observations reported in the WHO report is followed by an account of the post-World War II years at the Tavistock Clinic and Bowlby’s cooperationwith James Robertson. It will become clear that Robertson’s work was highly influential for Bowlby’s thinking on attachment. Robertson’s observations of young children in hospital – the so-called sanatorium study – confirmed the early retrospective work that Bowlby had summarized in his WHO report.

In Chapter 4, I will focus on the cross-fertilization of Bowlby’s ideas and those of various leading European scientists in the field of ethology. From the 1950s, Bowlby was in close personal and scientific contact with the likes of Niko Tinbergen, Konrad Lorenz, and Robert Hinde and he used their new viewpoints and theoretical framework to explain his earlier observations and to develop his new theory on attachment. These ethologists in their turn were influenced and inspired by Bowlby’s thinking. Attention will be paid to Bowlby’s influence on ethological studies in general and on Hinde’s work more specifically.

Subsequently, I will show how Bowlby made the move from theoretical and observational claims to experimental evidence through his interactions with American animal psychologist Harry Harlow, with whom he was in contact from 1957 through the mid-1970s. Bowlby profited highly from Harlow’s experimental work on the effects of separation in infant rhesus monkeys. Here again, an attempt is made to delineate the cross-fertilizing aspect of the interaction by showing that Harlow in his turn was influenced and inspired by Bowlby as well.

Chapter 6 deals with the contributions of Mary Ainsworth to Bowlby’s theory, as I consider her a co-founder of the attachment paradigm. I will relate Ainsworth’s development as an experimental researcher by describing her work in Uganda and in Baltimore. I will trace the origin of the concept of a secure base, a notion Bowlby later incorporated into attachment theory, to the work of Ainsworth’s mentor William Blatz. Also, I will describe the early development ofthe Strange Situation Procedure and the crucial role of maternal sensitivity for the development of attachment.

Finally, I will integrate and discuss the evidence presented in this book. How did Bowlby make his move from psychoanalysis to ethology during the most eventful years of his career in the 1950s and 1960s? What influences on his thinking and ideas can be exposed? How can the impact of people like Robertson, Ainsworth, Hinde, Harlow, and others best be described? What is the result of the interaction with ethology in Bowlby’s Attachment and Loss? And what about Bowlby’s scientific descent: was it Freudian or Darwinian?