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Ethological Attachment Theory: A Great Idea in Personality?

Patricia Pendry
Northwestern University

This paper critically reviews the ethological attachment theory as proposed by Bowlby and Ainsworth in order to examine if attachment theory is a great idea in personality. The most important aspects of attachment theory are presented and two critical questions are posed. The first question is, Can attachment theory be supported by empirical evidence? To answer this question, a variety of studies will be reviewed, each of which examines a specific aspect of attachment theory. The second question is whether the phenomena explained by creators and proponents of ethological attachment theory could have been explained differently, using other psychological mechanisms. These are two criteria that must be met if attachment theory is to be considered a great idea.

Attachment is the strong emotional bond that develops between infant and caregiver, providing the infant with emotional security. By the second half of the first year, infants have become attached to familiar people who have responded to their need for physical care and stimulation. How this attachment develops has been a topic of intense theoretical debate. Theories that attempt to explain attachment are abundant but scientifically verifiable explanations have been elusive. How does attachment develop and which factors affect it? Is attachment security a stable factor? How is attachment security measured? These are all questions of great theoretical and practical interest that can be answered from diverse perspectives.

One group of clinicians and researchers, known as attachment theorists, claims that they have found some answers and are close to finding others. But although they have impressed many of their colleagues, and changed some of our most basic opinions about early child development, their accomplishments have often been met with skepticism and opposition. The view that is widely accepted today is the ethological theory of attachment.


Ethology is concerned with the adaptive, or survival, value of behavior and its evolutionary history (Hinde, 1989). It was first applied to research on children in the 1960s, but has become more influential in recent years. The origins of ethology can be traced to the work of Darwin. Its modern foundations were laid by two European zoologists, Lorenz and Tinbergen (Dewsbury, 1992). Watching the behaviors of animal species in their natural habitats, Lorenz and Tinbergen observed behavioral patterns that promote survival. The most well known of these is imprinting, the early following behavior of certain baby birds that ensures that the young will stay close to the mother, and be fed, and protected from danger. Observations by ethologists have shown that several aspects of children's social behavior, including emotional expressions, cooperation, and social play, resemble those of our primate ancestors. According to the ethological view, babies are biologically prepared to contribute actively to establish a bond with their caregivers, which promotes the chances for their individual genes to survive. Since ethologists believe that children's behaviors can be best understood in terms of their adaptive value, they seek a full understanding of the entire organism-environment system, including physical, social, and cultural aspects (Hinde,1989). Although ethology emphasizes the genetic and biological roots of development, learning is also considered important because it lends flexibility and adaptiveness to behavior.

Bowlby and Attachment

Bowlby (1969), who first applied this idea to the infant-caregiver bond, was inspired by Lorenz's (1952) studies of imprinting in baby geese. He believed that the human baby, like the young of most animal species, is equipped with a set of built-in behaviors that helps keep the parent nearby, increasing the chances that the infant will be protected from danger. Contact with the parent also ensures that the baby will be fed, but Bowly was careful to point out that feeding is not the basis of attachment.

According to Bowlby, the infant's relationship to the parent begins as a set of innate signals that call the adult to the baby's side. As time passes, a true affectionate bond develops, which is supported by new cognitive and emotional capacities as well as a history of consistent, sensitive, responsive care by the parent. Out of this experience, children form an enduring affectional bond with their caregivers that enables them to use this attachment figure as a secure base across time and distance. The inner representation of this parent-child bond becomes an important part of personality. It serves as an internal working model, or set of expectations about the availability of attachment figures, the likelihood of receiving support from them during times of stress, and the interaction with those figures. This image becomes the basis for all future close relationships during infancy, childhood, adolescence, and adult life.

Perfect Sense?

At first glance, Bowlby's attachment theory makes perfect sense. It seems only right that our earliest relationships become an important part of our lives, and that the internal working models guide us throughout future relationships. However, even though attachment theory makes good sense, we have to evaluate the empirical evidence used to support it. There are several questions we must ask ourselves about the ethological approach to attachment. Lorenz's (1952) studies on imprinting in geese may be persuasive, but what can animal studies really tell us about our human bonding behaviors? How do we know that infant attachment is not merely a function of feeding? And what about the phenomenon of a secure base and internal working model? Do they exists or are they just vague concepts, unsupported by data? Also, if attachment security exists, we should be able to classify and measure it. Are the tools used by attachment theorists valid? Can they be used cross-culturally?

In addition to critically examining the evidence brought forward by ethological attachment theorists we should investigate if attachment can be explained through other mechanisms. Maybe it is not just the caregiving style that affects attachment security. Maybe it is not the early experience or environment that matters at all. We need to look at the possibility that attachment security is influenced biologically in correlation with temperament. If this were to be found true, the basis of attachment theory could be challenged. The question is this: Can attachment theory withstand the challenge?

Animal Studies

Temperament was not a factor in a now famous study performed by Harlow, an animal learning theorist. He was inspired by studies that showed that infants raised in orphanages without handling or loving attention withered away, and often died (Spitz, 1946). Harlow designed an experiment with infant rhesus monkeys, whom he took away from their mother shortly after birth, and raised with two different surrogate mothers instead. One 'mother' was made of bale-wire mesh, the other was covered with terry cloth. Each mother could be equipped with a feeding nipple. Even when the bale-wire mother was the only one providing food, the infant monkeys became more attached to the terry cloth mother and used her as a secure base to explore their environments. This experiment seriously challenged the view of social learning theorists and psychoanalysts who viewed attachment mainly as a function of feeding. Contact and comfort appeared to be most important in the development of attachment, not feeding (Harlow & Zimmerman, 1959).

Although the results of this study seem to indicate that feeding is not the most important factor that ties an infant to a caregiver, we cannot say anything definitive about attachment in humans based on this study. Because it would be unethical to conduct a similar experiment with human babies, it is impossible to predict the outcome with certainty. However, observations of human infants reveal that they can become attached to family members who seldom if ever feed them, including fathers, siblings and grandparents (Shaffer & Emerson, 1964). In addition, a study was done that offered an interesting similarity to Harlow's, which showed that toddlers, usually in the Western world, who sleep alone and experience frequent daytime separations from their parents, sometimes develop a strong emotional tie to a soft, cuddly toy or blanket. These objects of attachment are effective sources of security that seem to substitute for special people when such people are not available (Passman, 1987), yet such objects have never played an important role in feeding.

Behaviorist Perspective

Behaviorists had given feeding a central role in the development of attachment. According to Hull's drive reduction model, the baby's hunger, the primary drive, is satisfied repeatedly by the mother. Her presence therefore becomes a secondary or learned drive, because pairing occurs with the relief of hunger and tension. As a result, the baby learns through experience to prefer all kinds of stimuli that come along with feeding activity, such as warm bodily contact, eye contact, and verbal communication (Sears, Maccoby, & Levin, 1957).

Another behaviorist explanation of attachment is a model based on Skinner's principle of operant conditioning. Skinner rejected Hull's idea that primary drive reduction is the only way to get children to learn. According to Skinner, a child's behavior can be increased by following the behavior with a wide variety of reinforcers besides food, such as praise or a new toy. Certain behaviors can also be decreased through punishment, such as withdrawal of privileges, scolding, or taking away a new toy. According to the theory of operant conditioning, which emphasizes reciprocal responsiveness between the caregiver and baby, babies are reinforced to smile and look at their mothers, because in return they receive social interaction. The greater the number of infant behaviors that have been reinforced consistently, the stronger the attachment relation is (Gewirtz, 1969).

This explanation seems to make sense, but it has a great weakness in that it cannot explain why children exhibit attachment behaviors even though their caregivers may seriously mistreat them. This phenomenon has been supported by animal studies, which showed that babies who were treated violently by their mothers continued to seek physical contact (Seay, Alexander, & Harlow, 1964). It is a well-known fact that children who are regularly abused often continue to make similar attempts to approach their abusive parents.

Another critique of the behaviorist model of conditioning is that, according to this principle, the behavior should be extinguished if the stimulus stops occurring. We know this does not hold true. Even if you do not see the people you are attached to, you will most likely continue to have a desire to see them, and will seek closeness with them. It seems that even though ongoing 'reinforcement' is non-existent, once attachment is formed, it persists. It is clear that behavioral mechanisms simply cannot be used adequately to explain and account for the most basic findings that support attachment theory.

Measuring Attachment

Although it has been shown that most children will be become attached by the second half of their first year of life, it is interesting that the nature and quality of this relationship differs greatly from child to child. Some infants are especially relaxed and secure in the presence of their caregiver, other seem more anxious and uncertain. The question is this: How do we classify different attachment behaviors and how do we measure them accurately?

This question was answered by Ainsworth et al. (1978), who developed a measure to study the factors that influence attachment and its impact on later development. The Strange Situation is the most widely used technique for measuring the quality of attachment between 1 and 2 years of age. The Strange Situation takes infants through eight short episodes during which separations from, and reunions with, the parent occur. By observing the responses of infants to these episodes, researchers have identified a secure attachment pattern and two patterns of insecure attachment (Ainsworth et al., 1978).

Empirical Evidence

Before the infants' behavior was assessed in the Strange Situation, researchers closely observed mothers and children in their homes, paying careful attention to each mother's style of responding to her infant in a number of fundamental areas: feeding, crying, cuddling, eye contact, and smiling. At twelve months the infant and his or her mother were taken to the lab and the infant was observed as the infant was separated from his or her mother, as well as upon the mother's return.

Ainsworth noted three distinct patterns in the babies' reactions. One group of infants protested and cried on separation, but when the mother returned, they greeted her with pleasure and were easy to console. She labeled this group securely attached. The second group of infants was characterized by a lack of distress during parental separation, and avoidance of the parent upon return. This group was called insecurely attached, and avoidant. The third group was labeled ambivalent or anxiously attached, and tended to be clingy from the beginning and afraid to explore the room. They became terribly anxious upon separation, yet displayed angry and resistive behavior upon the parent's return.

In designing this study, Ainsworth and her colleagues reasoned that if attachment had developed well, infants and toddlers should use their parents as a secure base from which to explore their environments. In addition, when a parent leaves the room for a brief period of time, the child should show separation anxiety, and an unfamiliar adult should be less comforting than the parent. This concept has been supported by studies that measure infants' reactions in the Strange Situation, which closely resemble their use of the parent as a secure base and their response to the separation in the home environment (Blanchard & Main, 1979).

Acclaim and Caution

The Strange Situation has been widely acclaimed because it seems to enable researchers to identify and measure the security of infant attachment. Furthermore, individual differences in attachment security seem related to prior patterns of infant-parent interaction, a finding that is consistent with the common belief that children's social relationships are shaped by their earliest social experiences. However, before we accept the Strange Situation as a tool to accurately measure attachment security, we need to examine its validity.

There is a variety of reasons why we should look at the results of Ainsworth et al.'s (1978) longitudinal study with caution. First of all, the sample of participants (26 infant-mother pairs) was small compared to the number of variables. A sample of 26 infants is simply too small to be divided up into 3 groups and 7 subgroups. It seems that the researchers easily could have overanalyzed trivial differences among the infants and, as a result, too many subgroups were created. In order to confirm that the 7 subgroups indeed exist, it would have been helpful if a second group of participants, possibly larger in size, had yielded the same results. This is especially important because the initial measures were not derived on a priori theoretical grounds, but rather after an examination of the results.

Second of all, there was substantial opportunity for the data to be inaccurate, mainly because the observers who rated the children's behavior in the home were often inexperienced raters who were asked to make subjective evaluations of both the infant's and mother's behavior. Considering the fact that these home sessions occurred over a considerable length of time, it is easy to see how raters could have become biased in their ratings. Also, the raters used during the Strange Situation were sometimes the same raters who had assessed the infants in the home setting, so one can argue that their measurements could easily be biased through their previous contact and experience, because raters already knew the child and mother, and may have had certain expectations. Considering that interrater reliability was never assessed, all results should be replicated in independent larger samples before they can be considered reliable.

The most important question one should ask is if this study provides enough findings to base a theory on it. Can one base a theory on a measurement that highlights several minutes of reunion behavior in an unnatural and unfamiliar laboratory setting to reveal an emotional history between parent and child of a whole year? In my opinion, the answer is no. These findings can only obtain generalizability when replicated in independent studies in which bias is controlled and a priori predictions are tested and verified. Therefore, Ainsworth et al.'s (1978) study should be viewed as a study that generated hypotheses, not that tested them.

In defense of ethological attachment theory, one must say that it has generated an incredible body of research focused on understanding the social, emotional, and interpersonal development of children. In addition, there is substantial empirical evidence that supports the existence of the core elements of attachment theory (Grossmann, 1985).

Internal Working Models

One particularly interesting study assesses the workings of adults' internal working models through the use of the Adult Attachment Interview, an interview designed to measure parents' state of mind with respect to attachment (George, Kaplan, & Main, 1985). During the interview, parents are asked to describe and evaluate their childhood memories of attachment experiences in important relationships. How parents interpret their experiences provides an overall impression of the adults' working models. Four specific and distinct patterns emerge that show that the assessment of mothers' attachment security consistently corresponds to the attachment classification of their children. In fathers this relation is less clear, which indicates that caregiving is the determining factor, not heredity. This 'transmission' of attachment patterns supports the idea of internal working models that extend into adulthood as guides for future relationships, as well as indicates that attachment security is stable over time.


Studies indicate that attachment is highly stable over the first two years of life (Owen et al., 1984) and through the first 6 years of life (Main & Cassidy, 1988; Wartner et al., 1994). However, upon closer examination of these studies it is important to notice that the participants were infants who were living in a middle class environment and were experiencing stable life circumstances. One could argue that, by using this type of sample, the researchers set themselves up to support stability of attachment by not examining environmental factors that could influence this development. It has been shown that stability is affected when the family experiences major life changes (Thompson, Lamb, & Estes, 1982) such as parents' change of marital status, the birth of a sibling, or a change of a parent's employment. Because attachment theory is relatively recent, it will take years to test attachment stability through the use of longitudinal studies. Due to methodological and logistical challenges it is questionable whether the stability of attachment will be empirically supported in the near future.

Cross-Cultural Studies

The same type of methodological challenges are faced by those interested in testing the use of the Strange Situation cross-culturally. One study in Japan identified a very high number of infants displaying a resistant response indicating insecure attachment. This outcome could mean that Japanese children are more likely to be insecurely attached, or it could mean that the Strange Situation is a tool that cannot be interpreted similarly in Japanese children and American children. One could argue that the Strange Situation caused the Japanese children much more stress than the American children, simply because in Japanese culture children tend to be with their mother all the time, whereas American children frequently have experienced separations from their mothers. Again, further study is needed to establish guidelines to interpret the results from the Strange Situation in varying cultures.

An alternative to the Strange Situation was recently designed that could potentially increase the accuracy in determining attachment security across cultures and populations: the Attachment Q-set. An observer, the parent, or an expert informant sorts a set of 90 descriptors of attachment-related behaviors (such as, 'child greets mother with a big smile') into nine categories, ranging from highly descriptive to not at all descriptive of the child. The resulting profile indicates the degree to which a child displays secure base behavior (Waters et al., 1995). Q-set assessments by expert informants correspond well with the Strange Situation attachment classification; those by mothers do not (Van Dam & Van Ijzenhoorn, 1988; Vaughn & Waters, 1990).

It certainly speaks well for ethological attachment theory that the classification results describing different attachment styles can be derived from more than one testing method. However, we should investigate if Ainsworth and Bowbly's findings can be explained from a different perspective, that of genetic influence.


Heredity seems to have the strongest influence on physiological functions such as sleep and feeding patterns and the infant's level of excitability. By following babies throughout their first eight years of life, Kagan (1989) has found one personality trait, shyness, that appears to be linked to biological differences. About one infant in ten seems subdued and restrained in new situations, and three quarters of these infants go on to become shy and inhibited children. Their shyness seems related to physiology; extremely shy children have an abnormally low stress threshold so that during the mildest stress their heart rate, muscle tension, and hormonal levels differ form those of other children. A genetic basis to shyness has also appeared in twin and adoption studies. (Plomin et al., 1988). One could argue that Kagan's findings indicate that children's inborn temperament is partly responsible for the way babies respond in the Strange Situation. Babies who are irritable and fearful may simply react to the brief separation with intense anxiety even though the parent may have consistently displayed very responsive behavior and care to the baby throughout its life. Research shows that children who possess a disposition to stress in early infancy are prone to develop insecure attachment later (Seifer et al., 1996; Vaugh et al., 1992).

One could argue that attachment development is not determined by the nature and quality of the infant-caregiver relationship but instead by the infant's temperament. However, in order to critique a great theory, one should apply a reasonable approach, one that attempts to take into consideration a variety of mechanisms, one that is eclectic in nature. To claim that temperament is the overriding factor in the development of attachment would be a mistake.

Studies have shown that most securely attached infants develop particular distinctly different attachment bonds with each parent and the infants' varied caregivers (Goossens & Van Ijzendoorn, 1990). One could argue that if temperament were the overriding factor in establishing attachment quality we would expect attachment classification to be more constant across caregivers than it is. This should have led to the establishment of a similar attachment classification for all caregivers, but studies do not support this (e.g., Goossens & Van Ijzendoorn, 1990). However, this is not to say that temperament has no effect on the establishment of attachment security.

Given that attachment security describes the interpersonal relationship between infant and caregivers, one could easily see that personality traits and temperament play an active role in the dynamics of establishing this relationship. Attachment theorists recognize this aspect and note that it is exactly the concept of sensitive caregiving that forms an effective predictor of the quality of the attachment bond. A major reason that temperament and other child characteristics do not show strong relationships with attachment security may be that their influence depends on goodness-of-fit. From this perspective, many attributes of children can lead to secure attachment, as long as the caregivers modify their behavior to fit the needs of the baby (Seifer & Schiller, 1995). But when a mother's capacity to do so is limited by her own personality or stressful conditions then infants with difficult temperament or problem behaviors are at risk for developing attachment insecurity. According to attachment theorists, sensitive caregiving implies that regardless of the innate temperament of the infant, whether introverted or extraverted, whether shy or irritable, whether outgoing or confident, the care is adjusted to fit precisely the need of that particular infant. It is this eclectic nature of ethological attachment theory that becomes another strength.


It is strengths like these that make ethological attachment theory a great theory. The ethological approach to attachment offers a variety of strong arguments. Research has shown that the concepts of a secure base and internal working models exist and play an important role in the development of relationships in infancy, childhood, and adulthood. And although critics may argue that it has been difficult to duplicate the empirical findings of Ainsworth et al. (1978) in a large number of studies, their findings certainly justify an ethological attachment hypothesis. Certainly, at that time, no other study had successfully classified and measured attachment security in such a comprehensive manner. Although the Strange Situation has been criticized for not reflecting cultural variation in cross-cultural studies, it has provided researchers with an excellent tool to measure attachment security in infants. The concept of attachment style has also formed an excellent basis to support the stability of attachment in older children. In addition, attachment proponents are working hard to find measures that can be used across cultures and cohorts, and the development of the Q-set is a significant improvement. Also, ethological attachment theory is generating a tremendous amount of research into child development and related areas, which is extremely valuable for the science of psychology. Finally, although critics of attachment theory have challenged its findings over the last 30 years, no other discipline has presented empirical evidence that supports a more comprehensive overview of the phenomenon of attachment and its implications. Compared to behaviorist and biological perspectives, ethological theory provides the most accurate and effective explanation of the development of attachment. Although time will tell if attachment theorists are right, their findings provide an excellent framework to motivate parents and other caregivers to provide highly sensitive and responsive care to children throughout the world, if only for the benefit of humankind.


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