In the strange situation procedure, when do ambivalently attached infants act ambivalently?

Insecure-Resistant

Insecure-resistant infants, on the other hand, openly exhibit anxiety about both exploration and the availability of the attachment figure. This hyperactivation of the attachment system serves to keep the infant close to the caregiver, but at the expense of exploration. These infants often become more distressed during separation than secure or avoidant infants. On reunion, infants show obvious anger and resistance to contact with the caregiver. It is characteristic of resistant infants to seek contact, but to then push away efforts to comfort. For resistant infants, the presence of the parent does not have a calming effect, and returning to exploration can be difficult.

II Organization of Attachment

Human infants are biologically predisposed through evolution to form attachments to caregivers (Bowlby, 1969). Attachments may not occur only under exceedingly rare life conditions, where there is no stable person with which the infant can interact, such as in certain kinds of institutional rearing. In family-reared infants, the issue is not the presence of attachment, nor its strength. Rather, attachment theory identifies individual differences in attachment as categorical rather than as quantitative (Ainsworth, Blehar, Waters, & Wall, 1978; Bowlby, 1973). A central tenet of attachment theory from its inception has been that an infant’s attachment develops within the context of, and is therefore strongly shaped by, early caregiver–child interactions (Bowlby, 1969; Belsky, 1999). Bowlby (1973) postulated that through a history of responsive care, infants evolve expectations of their caregiver’s likely responsiveness to their signals of distress or need for comfort and contact; that is, the type of attachment they develop depends on the nature of the environments in which they are reared. Security of attachment was defined as a preferential desire for contact with the caregiver under conditions of threat or fear.

Ainsworth developed the Strange Situation (Ainsworth et al., 1978) to examine infants’ interactive behavior with their caregiver under conditions of mild to moderate stress of the attachment system. The Strange Situation introduces a laboratory situation that is unfamiliar, an unfamiliar adult who interacts with the child, and two brief separations from the mother. The reasoning is that the multiple increasing stressors will activate the infant’s attachment system and that individual differences in the child’s expectations of the caregiver will be revealed. Simultaneously, the Strange Situation demonstrates the infant’s ability to balance the need for comfort and reassurance from the caregiver with exploration of the new environment.

Ainsworth discovered and described three patterns that infants show in the Strange Situation. As explicated by Weinfeld, Sroufe, Egeland, and Carlson (1999), infants classified as secure use the caregiver as a secure base from which to explore the novel room and novel toys. The secure infant, in the presence of the caregiver, explores the toys, even while checking back with the caregiver or showing the toys to the caregiver. Upon separation, the infant’s play becomes impoverished, and the infant may become overtly distressed. Upon reunion with the caregiver, a distressed secure infant will seek proximity or contact, will be comforted by the proximity or contact, and will eventually return to play. Secure infants who do not become overtly distressed during separation still respond to the caregiver’s return by initiating interaction with a smile or vocalization.

Infants classified as insecure avoidant also explore the toys in the presence of the caregiver, but the infant is unlikely to smile or vocalize or to show the toys to the caregiver except for instrumental assistance. Upon separation, the insecure avoidant infant is unlikely to become distressed when the stranger is present, although some distress may be shown when left completely alone. Upon reunion, the infant ignores, or looks or turns away, or moves past the caregiver without approaching. If picked up, the insecure avoidant infant does little to maintain the contact.

Infants classified as insecure resistant do not seem to be able to use the caregiver as a secure base from which to explore. Their play may be limited and they may seek contact and proximity from the caregiver even before separation occurs. Upon separation, insecure resistant infants are likely to become quite distressed. Upon reunion they may seem to want proximity or contact with their caregiver but are not comforted by it. Some insecure resistant infants are oddly passive, crying but failing to actively seek contact; others seek contact, and then resist it with displays of anger.

Among nonnormative groups, attachment patterns are seen that are themselves atypical and inconsistent with Ainsworth’s original classifications. In normative or low-risk groups, 85–90% of children typically can be described by the original three categories (Main & Solomon, 1986; Sroufe & Waters, 1977), but with atypical groups, only 15–65% of children can be categorized as secure, insecure avoidant, or insecure resistant (Barnett, Butler, & Vondra, 1999). In fact, four atypical attachment patterns have been identified in normative and atypical children: disorganized/disoriented (Main & Solomon, 1986, 1990), avoidant/ambivalent (Crittenden, 1985), unstable/avoidant (Lyons-Ruth, Connell, Zoll, & Stahl, 1987), and unclassified. We will focus on the disorganized/disoriented classification because most research has been done using that category, in part because it incorporates many features of the avoidant/ambivalent and unstable/avoidant classifications.

Three overlapping levels of deviation from normative patterns of behavior in the Strange Situation are considered (Barnett & Vondra, 1999). First, at the level of organization of behavioral systems, secure children move smoothly in predictable sequences of approach and contact with the caregiver during distress, followed by relief, and then autonomous exploration and play. That is, the attachment, fear–wariness, and exploration systems are coordinated. Children with atypical patterns may neither explore nor show attachment behavior to the caregiver, or they may show fear–wariness simultaneously with attachment. Second, at the level of behavioral interactions, secure children tend to show low levels of avoidance and resistance and to show positive affect by smiling at and vocalizing to the attachment person (Waters, Wippman, & Sroufe, 1979). Those who are not overtly distressed on separation from their caregiver tend to show low-to-moderate proximity-seeking and contact maintenance upon reunion, whereas those who get highly distressed tend to show high levels of proximity-seeking and contact maintenance. In contrast, children with atypical patterns may combine high separation distress with low proximity-seeking and contact maintenance upon reunion; or show low levels of avoidance and resistance but a marked absence of positive affect; or show high levels of both avoidance and resistance. Third, at the level of discrete behaviors, secure children never show dazed or fearful facial expressions, freezing or stilling, or covering the mouth on the approach of the attachment person. Children who show these behaviors are atypical (Main & Solomon, 1986), even when the overall sequencing of behavioral systems or overall interactive pattern of behaviors are normative. However, these behaviors must be characteristic of the relationship; that is, they must occur with increased frequency around the caregiver and not simply reflect neurological or genetic impairments, such as motoric stilling in children with cerebral palsy or hand-flapping or self-stimulating behavior in autism (Atkinson et al., 1999; Main in Capps, Sigman, & Mundy, 1994; Pipp-Siegel, Siegel, & Dean, 1999).

Disorganized early attachments are probably a marker of a process that may lead to later increased pathology (Sroufe, Carlson, Levy, & Egeland, 1999). In the few published studies, the disorganized/disoriented classification is associated with later social–emotional problems, particularly oppositional or hostile–aggressive behaviors (Lyons-Ruth, 1996). Furthermore, children with disorganized attachment patterns have been found to be more vulnerable to altered states of mind such as dissociation in young adulthood (Carlson, 1998).

Although some investigators have questioned whether atypical attachment patterns are more unstable across time than typical attachment patterns (Lyons-Ruth, Repacholi, McLeod, & Silva, 1991; Vaughn, Waters, Egeland, & Sroufe, 1979), the evidence is inconsistent on the degree of stability for both typical and atypical attachment patterns. Some investigators find significant stability from infancy to adulthood of typical attachment patterns (77%, Hamilton, 2000; 72% Waters, Merrick, Treboux, & Crowell, 2000). Other investigators find significant change (50%) even from 12 to 18 months (Vondra, Hommerding, & Shaw, 1999), a degree of change that exceeds that reported in atypical children such as Down syndrome children (62% stability from 26 to 42 months, Atkinson et al., 1999) and maltreated children (66% stability from 12 to 18 months, Barnett, Ganiban, & Cicchetti, 1999).

Changes in attachment organization clearly exist among all groups—typical and atypical. Such changes do not diminish their developmental significance. Changes are probably lawful and related to changes in the family environment or characteristics within the developing child. Although few studies exist that test the continuity and change in attachment organization in atypical groups, much could be learned in the future about the evolving nature, causes, and consequences of attachment patterns among atypical mothers and children.

3.1.1.2 Attachment Patterns

Ainsworth identified three major attachment classifications. Secure infants use their caregivers as a “secure base” for exploration. These infants rely on occasional visual, verbal, or physical contact with their mothers as a basis for their own initiated exploration of the environment. When their mothers leave the room, secure infants may or may not cry. On reunion, these infants either greet their mothers positively or, if upset, go to them for comfort and then shortly after return to activities associated with exploration.

Infants who show patterns of insecure attachment of the avoidant type exhibit little or no reference to their mothers while exploring the room and show no overt signs of distress on their mothers’ departure (although some studies have shown that these infants do show physiological markers of stress during separation). Most important, on reunion, these infants actively ignore and avoid their caregivers (e.g., by looking away).

Insecure–resistant (or ambivalent) infants are preoccupied with their mothers’ presence, often unable to leave their sides even in light of curious attempts to explore their new environment. When their mothers leave the room, these infants become extremely distressed, and on reunion, the infants refuse to settle and to resume exploration, clinging to their mothers and at the same time expressing anger and dissatisfaction.

The large body of work using the Strange Situation shows that across cultures, the majority of all infants (approximately 65%) are securely attached to their mothers, whereas the remainder are classified as insecure. The distribution of insecure attachment classifications (i.e., frequencies of the avoidant and resistant patterns) appears to be affected by cultural context. In Western Europe and the United States, the avoidant type is more prevalent than the resistant pattern, whereas the opposite has been observed in some other cultures (e.g., in Israel).

A fourth category of attachment classification was added in 1986 by Main and Solomon because studies showed that there are infants whose behavior does not correspond with any of the three existing classifications. During the Strange Situation, these infants showed sequences of unusual behavior with no clear purpose or orientation (e.g., freezing, falling prone). They seemed to lack an organized strategy for coping with the stress of the situation and looked “confused”; thus, they were classified as having disorganized/disoriented attachment to their caregivers. Disorganized classification is given in addition to one of the other classifications. In normative middle-class populations in North America, approximately 14% of infants are judged to be disorganized. The rate is somewhat higher (24%) in low-socioeconomic status samples.

B Ainsworth: infant attachment and mothers’ sensitivity to their infants’ representational worlds

Ainsworth, a close colleague of Bowlby, made significant contributions to attachment theory by expanding Bowlby's (1969/1982, 1973, 1980) original ideas about the nature of attachment security versus insecurity, and about mothers’ contributions to their children's quality of attachment. First, she is credited with advancing the notion that an infant's use of the mother as a secure base is a normative feature of the infant–mother attachment relationship and that the nature of this secure base use provides a window into the quality of the child's attachment to the mother (i.e., if the attachment relationship is secure, infants will use their mothers as secure bases from which to confidently explore the environment; Ainsworth, 1967; see also Sroufe & Waters, 1977). The secure base notion, which was based largely on Ainsworth's field observations in Uganda, has been instrumental to the development of attachment theory since its introduction and complemented Bowlby's earlier perspective that the infant uses the mother as a safe haven to which to return in times of need and/or distress.

Second, Ainsworth and her collaborators designed the Strange Situation procedure, which remains the most widely used method of assessing quality of attachment to a caregiver in infancy (Ainsworth et al., 1978; Ainsworth & Wittig, 1969; see Cassidy, Marvin, & the MacArthur Attachment Working Group, 1992; Main & Cassidy, 1988; Waters & Deane, 1985, for related measures). During this 20-min procedure, an infant undergoes two brief separation and reunion episodes with a caregiver; the separations are thought to be stressful (thereby activating the infant's attachment system) and the reunions shed light on whether and how the infant uses the caregiver as a comforting safe haven and/or a secure base from which to reengage in exploration after stressful separation events. Observations of 12–18-month-old infants’ responses during these episodes have revealed that infants typically display one of three distinct patterns of attachment behavior. Secure infants use the caregiver as both a safe haven and secure base during the Strange Situation; they seek proximity to their parents when stressed (usually through, but not limited to, direct physical contact), derive comfort from such proximity, and reengage in exploration once they have been comforted satisfactorily. Insecure-avoidant and insecure-resistant infants, however, fail to use their parents successfully as safe havens and/or secure bases during the Strange Situation. More precisely, insecure-avoidant infants do not seek proximity to their parents during the Strange Situation. Insecure-resistant infants, in contrast, seek proximity to their parents, yet are unable to derive comfort from this proximity or to reengage successfully in exploratory behavior. After the discovery of these three patterns of infant attachment, Main and her colleagues identified a fourth pattern (insecure-disorganized), marked by the infant's display of relatively odd, conflicted, disoriented, and/or fearful behaviors in the Strange Situation (see Main & Solomon, 1986, 1990).

The notion of the parent as a secure base and the development of the Strange Situation procedure led to one of Ainsworth's most significant contributions to attachment theory and research, which was the empirical study of parental sensitive caregiving. On the basis of Bowlby's (1969/1982, 1973, 1980) earlier comments about the effects of maternal care and availability on a child's emerging attachment, Ainsworth and her colleagues believed that infants’ quality of attachment to mother expressed in the Strange Situation likely derived from the ways in which mothers had successfully (or unsuccessfully) responded to their infants’ attachment-related needs in the everyday home environment. By visiting mothers’ homes every three weeks during the infants’ first year, Ainsworth et al. (1978) identified four classes of maternal behaviors (which they later turned into observational rating scales) that could influence infant attachment security. She labeled these scales: sensitivity–insensitivity, acceptance–rejection, cooperation–interference, and accessibility–ignoring.

In addition to identifying the behavioral indices of caregiving sensitivity, Ainsworth et al. (1978) also emphasized the fact that sensitivity is rooted in how the mother attunes herself psychologically to her infant's representational world. For example, when describing the sensitivity–insensitivity scale, Ainsworth and her colleagues stated, “The optimally sensitive mother is able to see things from her baby's point of view. She is alert to perceive her baby's signals, interprets them accurately, and responds appropriately and promptly… She tends to give the baby what he seems to want” (1978, p. 142). Ainsworth's notion about what it meant to be a sensitive mother thus contained the idea that the mother had to be capable of tracking the baby's mind and the thoughts contained in it. Moreover, this mind-tracking had to synchronize with how the mother was processing her infant's behavior in real time. The other three scales contain similar ideas about how maternal sensitivity was embedded in a mother's capacity to be able to perceive the baby's wishes (and how they can be integrated into one's own wishes), to not distort the baby's behavior mentally, and to perceive one's self as a suitable caregiver. We present a summary of these four sensitivity scales and their information processing aspects in Table I. Overall, Ainsworth and her colleagues found that mothers of secure infants were more likely than those of insecure infants to demonstrate these capacities in the home with regard to supporting their infants’ secure base behaviors and serving as a safe haven when their infants’ attachment systems were activated. Mothers of insecure infants, however, did not show these capacities and struggled to attune themselves to their children's exploratory wishes and/or needs for a safe haven. Ainsworth's initial propositions have since been supported by a wealth of empirical data collected in the home and in the laboratory (see De Wolff & van IJzendoorn, 1997, for a review).

Table I. Summary of the information processing aspects of the Ainsworth Sensitivity Scales

Ainsworth's original ideas about the cognitive underpinnings of maternal sensitivity have been incorporated subsequently in much research on infant attachment and have spurred related ideas about mothers’ abilities to see things from the infant's point of view. For example, Meins (1997, 1999) developed the concept of maternal mind-mindedness, that reflects mothers’ capacities to use “information from their children's outward behavior in making accurate inferences about the mental states governing that behavior” (Meins, Fernyhough, Fradley, & Tuckey, 2001, p. 638). Relatedly, Oppenheim and Koren-Karie (2002) have examined maternal insightfulness, which they refer to as the capacity to understand a child's motives, to possess a complex view of the child, and to demonstrate openness to new information regarding the child. Overall, Ainsworth's groundbreaking attention to understanding how mothers process information about their infants during day-to-day experiences, and how such processing is related to infant attachment, set the stage for understanding the form and function of attachment in adults, which we discuss next.

Relationship disorders

Although psychiatry and psychology traditionally have considered disorders to be within-the-individual, the unique dependence of infants on their caregiving context have led some to suggest that disorders may exist between individuals – in this case, infant and parent. This approach is bolstered by clinical observations and research evidence of relationship specificity. What this means is that the young child may be symptomatic in the context of one relationship but not others.

In young children, a relationship with a nurturing, sensitive, responsive caregiver is one of the most important contributors to healthy development. In nonreferred children, the formal attachment classifications based on the strange situation procedure provide a way to understand various relationship patterns. A secure attachment is found in children who have had warm, sensitive, responsive caregiving, and can be observed when young children are able to seek and respond to comforting in a stressful situation. Three types of insecure attachment have been described. Insecure–avoidant is seen when young children respond to stress by not seeking, or actively avoiding, help from their caregiver. Insecure–resistant attachment is characterized by the young child who can signal his distress but has great difficulty getting effective comfort from the caregiver. The disorganized attachment classification is found in dyads in which the young child does not have coherent, reliable ways of signaling distress to the caregiver, often associated with bizarre or unusual behaviors.

The insecure attachment classifications can be predictive of later psychopathology, but these classifications do not necessarily indicate current pathology. For example, children who exhibit avoidant attachment behaviors in the strange situation are at risk of developing anxiety disorders, and those children with disorganized attachments have an increased chance of developing preschool behavior problems. These characterizations of the parent–child relationship also are associated with later behavior problems and social–emotional difficulties.

In some dyads, disordered patterns of behaviors as well as distortion of perceptions about the other in the relationship can impair the child or dyadic functioning at the level of a disorder. Attachment disorders are considered to reflect a significant disturbance in the relationship between the infant and his or her primary caregiver, such that it interferes with the child’s ability to develop normally in other domains, including cognitive, physical, behavioral, as well as social–emotional development.

Controversy remains about how best to diagnose attachment disorders. The DSM-IV-TR contains only criteria for the diagnosis of reactive attachment disorder (RAD). The diagnosis requires a total lack of an attachment relationship and requires a known history of maltreatment to make the diagnosis. However, even in situations of profound deprivation, it is rare for a child not to develop some type of attachment with a caregiver, most likely to be a disturbed type of relationship. In contrast to DSM-IV-TR, the RDC-PA provides an alternative means of concretely operationalizing the concept by clearly describing behaviors of disordered attachment, even in the context of an attachment relationship. Unlike the DSM IV, the RDC-PA does not mandate that the child has been maltreated. DC:0–3R has similar criteria for attachment disorders as RDC-PA, but also uses Axis II for diagnosis of problematic relationship patterns which do not meet the standards for reactive attachment disorders and/or which are not focused specifically on the attachment portion of the relationship.

Whatever the specific diagnostic criteria used, it is clear that clinically relevant disturbances in children’s attachment behaviors exist. A healthy attachment allows for a balance between the toddler’s developmentally appropriate exploratory drive and need for emotional reassurance and support. Children with healthy attachments to a caregiver or parent can use that person in an effective manner for comfort and are able to successfully begin to explore their environment in a safe way. Children with attachment disorders generally demonstrate two major patterns of behaviors: inhibited and disinhibited behaviors. Children with the inhibited form of RAD tend to be emotionally restricted, are overly cautious, and do not seek out comfort effectively, if at all. In the disinhibited type, children do not have the usual wariness of new situations and new people. They are excessively and indiscriminately friendly with unfamiliar adults and rarely check back with their parent, even in new environments where they may not know anyone. These two patterns of attachment disorders are not mutually exclusive; children can present with features of both patterns. Indiscriminate behaviors, but not inhibited behaviors, appear to persist in young children who have been raised in institutions such as orphanages, even after a child has been adopted and has developed a new attachment relationship with a committed caregiver. Although it is clear that disturbances of attachment may continue to put children at risk for other disorders, attachment disorders have not been studied in children older than 5 years, and the current descriptions of these disorders may not be helpful in the older age group.

Early childhood

Parent–child attachment styles. Classic work in attachment by Mary Ainsworth classified American infants according to a set of attachment styles, with secure being the most common and insecure variations (avoidant, ambivalent) being relatively less common (Ainsworth, Blehar, Waters, & Wall, 1978). Since then, researchers have set out to replicate these patterns of attachment styles in different cultures, and although there are similarities, there are a number of notable differences in attachment distributions that correspond with differences in cultural practices and values. In some cultures there seem to be differences, not in the proportion of secure attachment, but in the prevalent form of insecure attachment. In Japan, the insecurely attached infants were only insecure-ambivalent (also called insecure-resistant) rather than insecure-avoidant (Miyake, Chen, & Campos, 1985; Takahashi, 1986), and in Israel, there was a high frequency of insecure-ambivalent (Sagi et al., 1985); secure attachment was still the most common attachment style in both cultures. However, in Northern Germany the most common attachment style was insecure-avoidant, followed by secure and then insecure-ambivalent (Grossmann, Grossmann, Spangler, Suess, & Unzner, 1985). The authors of this research suggest that there seem to be differences in the way mothers interact with their infants in Northern Germany, where the culture may emphasize status and interpersonal distance even more than in North America, and these cultural differences may be related to the lower percentage of securely attached infants in Northern Germany.

Some cultural researchers have argued that the tenets of attachment theory, such as sensitivity and competence, are rooted in predominantly North American ideals of personal control and autonomy (Rothbaum, Weisz, Pott, Miyake, & Morelli, 2000), and in particular, the way that secure versus insecure attachment is manifested in children and interpreted by parents may differ depending on cultural values. For instance, mothers in the United States tend to associate secure attachment with a broader range of positive characteristics in personality and social skills, while Japanese mothers focus more on social roles and accommodating others in relationships as correlates of secure attachment (Rothbaum et al., 2007). The general message from these findings of cultural difference is that broader cultural values may be reflected in the relationship between caregivers and infants, leading to different patterns of attachment across cultures. Just as the caregiver–infant bond may change depending on the amount of resources or impending threats in the surrounding environment, it is perhaps unsurprising that different cultural ideals about how to be a good caregiver can have implications for patterns of attachment.

However, there are important similarities in attachment to note as well. While mothers in the United States and Japan may have different ideals for how a “good” infant should behave, mothers in both cultures agreed that secure attachment is related to desirable rather than undesirable child characteristics (Rothbaum et al., 2007). Consistent with this general finding, research comparing descriptions of secure-base behavior from mothers and childcare specialists found marked similarity across seven countries: China, Colombia, Germany, Israel, Japan, Norway, and the United States (Posada et al., 1995). Taking these findings of attachment similarities and differences together, it seems clear that caregivers across cultures are motivated to respond sensitively to their children in order to help them become good, competent members of society, but specific interpretations about what is “sensitive,” “competent,” or “good” may differ depending on culture. It is likely that the attachment system is attuned to responses from caregivers, which are inevitably shaped by a host of contextual variables, including resources and threats, as well as shared values and norms at the level of culture. Thus it is possible that different attachment styles very early in life (a form of personality) may be in part shaped by cultural information about good ways to interact with caregivers, with preferred attachment styles in a culture becoming relatively more prevalent and nonpreferred styles becoming less prevalent.

Big Five personality traits. Research on culture and personality can be traced to the Big Five personality research from the 1990s. The Big Five personality traits—Neuroticism, Extraversion, Openness, Agreeableness, and Conscientiousness—are supposed to capture the core features of personality. The Big Five personality structure appears to be well generalizable across different cultures and age groups (John, Caspi, Robins, Moffitt, & Stouthamer-Loeber, 1994; Schmitt, Allik, McCrae, & Benet-Martínez, 2007; Tackett et al., 2012), although Openness to Experience has not been identified in certain cultures and languages (De Raad et al., 2010).

Childhood is an important developmental period in its own right, especially for the development of personality. Childhood personality predicts a number of crucial future outcomes, including internalizing and externalizing problem behaviors (Denissen, Asendorpf, & van Aken, 2008), success and failure in school and the workplace (Asendorpf, Denissen, & van Aken, 2008), and social and romantic relationships (Ozer & Benet-Martínez, 2006; Simpson, 1999). A few studies have focused on personality development in young children, but most of these have been conducted in Western countries. In one longitudinal study, McCrae et al. (2002) examined personality changes of American and Flemish children from age 12 to 18. The largest age difference was observed for Openness, which increased from childhood to early adulthood in both cultural groups from the United States and Belgium, likely as a result of increased cognitive complexity. Neuroticism increased in girls but not in boys, and no differences were observed in the other three personality traits. Consistent with these findings, other studies provide further evidence that personality development largely follows the same patterns in childhood and adulthood. Individuals’ normative increases in maturity occur through their reactions to social and physical environments (Roberts et al., 2006).

Other research including a wide variety of age groups (from 10 to 65 years) provided further support for the U-shaped developmental trend for personality with decreasing maturity during early adolescence and increasing maturity thereafter through mid to late adolescence (Soto et al., 2011). In this study, participants from English-speaking countries provided personality ratings online (72% were residents of the United States). Children’s Conscientiousness levels, for instance, dropped in early adolescence but increased in mid to late adolescence. Although only a handful of studies have directly focused on young children from a cross-cultural perspective, many of these studies show evidence of similar developmental patterns for Big Five personality traits in different cultures, at least within North America and parts of Europe.

However, some studies show evidence of cross-cultural differences. One study by Branje, Van Lieshout, and Gerris (2007) compared mean levels of personality between young Dutch children aged 11–15 years and found age and gender differences in personality development. The results were somewhat inconsistent with previous results on American children. Openness increased in girls but not boys. Furthermore, Extraversion increased for boys, and Extraversion, Agreeableness, and Emotional Stability (reversed Neuroticism) increased for girls. These gender and age differences in the Netherlands may reflect cultural practices and perhaps genetic factors and socio-economic factors in the Netherlands. Compared to the United States, there is a greater gender gap in wages and labor force participation rates, in that men are more likely to be employed compared to women in the Netherlands (see Evertsson et al., 2009). Accordingly, these differences in cultural environments may interact with individuals’ personality, values, and beliefs (e.g., child personality and parenting philosophies). Another possible explanation is that there might be differences in genetic tendencies in the two cultures. Even if there are shared cultural values between the Netherlands and the United States, similar cultural environments can interact with the (potentially different) genetic tendencies in the two countries, which may lead to different psychological outcomes.

As most studies on personality development usually start in adolescence, at this time, it is difficult to draw definitive inferences about the contribution of genetic and environmental factors on personality development. Most studies on personality development of young children were predominantly conducted in North America and Western Europe; thus, more research needs to be conducted in cultural groups that are less frequently studied to examine intercultural similarities and differences in personality development among children.

Transmission of attachment through sensitive parenting

Combining the two core hypotheses we arrive at the basic model for intergenerational transmission of attachment that has been studied intensively in the past four decades. Adult attachment predicts child attachment, or more specifically: coherence of the parental narrative about attachment experiences predicts the child's balance between exploration and proximity seeking. Parents with an angry, preoccupied perspective on the way they were treated by their parents elevate the chance that their child develops an insecure-resistant attachment, whereas parents who dismiss the impact or memory of negative attachment experiences unwillingly stimulate an insecure-avoidant attachment in their child. Resistant children maximize their attachment behavior at the cost of exploration, avoidant children minimize the expression of their attachment needs.

Parental sensitive responsiveness to child signals is hypothesized to mediate the association between adult and child attachment (see Figure 1). Preoccupied parents tend to show inconsistently sensitive responses: they are insensitive to low-intensity attachment signals of their child but are usually sensitive to high-intensity signals such as crying. By contrast, insecure-dismissing parents are supportive of their child in stress-free conditions but disconnect when the child shows signs of discomfort and distress, questioning the parental capacity to deal with the child's negative emotions [14,15].

3.2.2 Longitudinal studies of infant attachment

Recently, a longitudinal G x E study examined the genetic and caregiving-based contributions to individual differences in infant attachment classifications in 154 mother-infant pairs (Raby et al., 2012). The mother's responsiveness to their 6-month-old infants was evaluated on the Ainsworth's global scales of maternal sensitivity and cooperation (Ainsworth et al., 1978) during two 30-minute feeding situations and one 20-minute play situation on two different days in their homes. The infants’ attachment was assessed twice in the Ainsworth Strange Situation procedure (Ainsworth et al., 1978), when the infants were 12 and 18 months. The infants were classified as securely attached, insecure-avoidant, or insecure-resistant. In addition, infants were categorized in a high-or-low distress group based on the level of emotional distress that they exhibited in response to the Strange Situation procedure (the attachment disorganization classification was not included in this study) (Raby et al., 2012). The results revealed that maternal responsiveness at 6-months of age predicted infant's attachment classification at 12-months of age (with greater responsiveness at 6-months of age being associated with a greater likelihood of secure attachment at 12-months) but not at 18-months of age. Maternal responsiveness did not show a main effect or an interaction with the short alleles of the 5-HTTLPR in predicting infants’ level of emotional distress at 12-months and 18-months of age (Raby et al., 2012). Despite the fact that the 5-HTTLPR showed neither a main effect or an interaction with maternal responsiveness in predicting attachment security at 12-months and 18-months of age, the s/s 5-HTTLPR genotype was associated with an increased risk of infants being categorized in the high-distress group (Raby et al., 2012). More specifically each s allele of the 5-HTTLPR increased two-fold the probability of the carrier being in the high-distress category at 12-months of age; the same result was observed at 18-months of age but only for children who were categorized as insecurely-attached (Raby et al., 2012).