Human Attachment

One principal line of investigation in my research is devoted to examining the psychological, behavioral, biological, physiological, and neural basis of human attachment, particularly in relation to attachment orientations / styles – i.e. inter-individual differences in secure versus insecure, anxious and avoidant attachment orientations. To obtain an idea why I think such research is important, please refer to my blog on the Evolution of the “social brain” in humans: what are the benefits and costs of belonging to a social species?

Some of the published articles and book chapters in association with my attachment research are outlined in more detail below. All of them can be found on the publications page of my website, or under my ResearchGate project “Human Attachment: Elucidating the underlying Psychological, Behavioral, Biological, Physiological, and Neural Basis“. The remaining sections of this page are organized as follows:

1) Attachment Theory
2) General Overview of my Attachment Research
3) The Neural Substrates of Attachment in Adults
4) The Neural Substrates of Attachment in Adolescents
5) The Neural Substrates of Attachment in Children
6) Attachment & Bio-Behavioral Synchrony 
7) The Genetics and Epigenetics of Attachment 


1) Attachment Theory

According to attachment theory (developed by Mary Ainsworth and John Bowlby), every child is born with an innate attachment system. The biological function of this attachment system is to enhance the chances of survival by means of proximity seeking mechanisms, particularly in times of stress and/or need. Although (almost) all children will become attached to one or several caregiver(s), the quality of attachment can differ considerably between individuals. Such inter-individual differences emerge because there is a psychological correlate of attachment behavior, namely a felt sense of security.

If proximity seeking attempts are successful, a child learns that attachment figures are available in times of need, a pattern that supports the development of a secure attachment. If proximity seeking attempts under stress do not succeed, however, the child will develop an insecure attachment. The latter can either be avoidant in case of consistently unavailable / unresponsive attachment figures, or anxious in case of unpredictable / unreliable attachment figures. Attachment theory suggests that such attachment patterns in early childhood become more and more cognitively encoded during child development,  remain rather stable across the life span, and can influence a variety of social emotional behaviors in childhood, adolescence, and adulthood (but see also here). The plot thickens that attachment traits can even be transmitted from one generation to the next, and that they not only influence directly attachment-related processes, but (almost) all social interactions between people.


2) General Overview of my Attachment Research

Initially focusing on healthy adult participants, my research on the neural substrates of attachment in humans has more recently been extended to also include healthy adolescents (ages 12 to 19) and children (ages 8 to 12 and 5). Besides using fMRI in single persons, I have also started looking at the influence of inter-individual differences in attachment on bio-behavioral synchrony measures in two participants by means of fNIRS hyperscanning. Such two-person approach appears important, because attachment patterns within parent-child dyads and parent-child-parent triads (i.e. families) are nowadays thought to be crucially dependent on behavioral and physiological synchrony (see here for an example). Finally, through international collaborations, I am also looking at the genetics and epigenetics of attachment, so far in  young healthy adults.


3) The Neural Substrates of Attachment in Adults

A general short summary of my attachment research in adults can be found in two of my blogs – The neural signature of attachment insecurity and The insecurely attached brain. Moreover, in 2012, Patrik Vuilleumier and I have published a first review paper in Frontiers in Human Neuroscience including a functional neuro-anatomical framework of adult attachment (see here), which I have recently updated in a book chapter on “The Social Neuroscience of Attachment“. Below is a Figure depicting our version of a possible attachment system in humans:


Neuro-anatomical framework of areas and their interrelations as well as modulatory neuro-transmitter/-peptide systems in association with human attachment  (style) (Vrtička, 2017

Neuro-Anatomical Framework of Human Attachment
In the above neuro-anatomical framework, Patrik Vuilleumier and I differentiate between an affective evaluation and a cognitive control module. Whereas the affective evaluation module is thought to process incoming information rather quickly and automatically, the cognitive control module represents more voluntary processes that can modulate affective evaluation mechanisms.

The so far available data in adults suggests that attachment avoidance and anxiety differentially influence affective evaluation and cognitive control mechanisms. While both insecure attachment orientations appear to (at least partially) interfere with emotion regulation mechanisms as part of the cognitive control module (see also here), attachment avoidance and anxiety seem to have opposite effects on affective evaluation processes. Attachment avoidance may be mainly associated with a general blunting of affective evaluation processes, particularly in the case of positive social information. In turn, attachment anxiety may be mainly linked to a general intensification of affective evaluation processes, especially in the case of negative social information.

Attachment as a Meaningful Adaptation to the Environment
Please note that attachment orientations represent specific adaptations to the environment attachment was formed in. Although it is generally understood that a secure attachment is most beneficial for social and emotional development, caution is advised in labeling attachment insecurities as inferior or detrimental. According to the Social Defense Theory, attachment insecurities may even represent specific advantages on the group level by providing the group with crucial information on an emerging threat and how to escape from the latter (for example, see here).

Cultural Differences in Attachment
It is also important to keep in mind that attachment theory was developed in a western, educated, industrialized, rich, democratic – in short WEIRD – cultural context, and that most research is still performed on WEIRD culture participants. More cross-cultural research therefore is still crucially needed to further extend and specify attachment theory and the emerging applied attachment research, on many levels. As nicely put by Rothbaum et al. (2000), “an awareness of different conceptions of attachment would clarify that relationships in other cultures are not inferior but instead are adaptations to different circumstances“ (p. 1101).

Different Neurobiological Models of Human Attachment
Finally, it should be mentioned here that there are two different neurobiological models of human attachment available in the literature.

A first prominent model by Helen Fisher (for example, see here) suggests that three principal human social behaviors can be dissociated by their underlying neurotransmitter / -peptide systems: (1) the sex drive / lust mediated by androgens, (2) attraction / mate choice / romantic love mediated by catecholamines, and (3) attachment mediated by oxytocin.
A second prominent model by Ruth Feldman (for a recent review, see here) suggests a differentiation of human attachment behaviors by means of four principal mammalian bonds, namely (1) parent-infant bonds, (2) pair-bonds, (3) peer bonds, and (4) bonds between conspecifics; and particularly by their degree of bio-behavioral synchrony.
In the above-described functional neuro-anatomical framework of adult attachment we propose, the models by Fisher and Feldman are also considered. These models, however, are extended by the notion put forward by attachment theory that the very same mammalian bond / attachment  – mediated by the very same neurotransmitter / -peptide systems – is subjected to strong inter-individual differences depending on the quality of the bond / attachment. For example, parent-infant bonds may be generally characterized by high bio-behavioral synchrony and prominently mediated by oxytocin, but strong inter-individual differences in the bio-behavioral signature are to be expected depending on the quality of the bond – the latter being reflected in secure versus insecure, anxious and/or avoidant attachment orientations (not only on the individual but also the dyadic and family level). What therefore is key in our model are inter-individual differences and their influence on the psychological, behavioral, biological, physiological, and neural basis of human attachment.


4) The Neural Substrates of Attachment in Adolescents

Adolescence is a crucial developmental period not only marked by important changes in brain anatomy and physiology, but also in a person’s attachment settings. Whereas in early life, attachment figures are mostly parents and/or other close family members, adolescence is characterized by the emergence of additional attachment relationships outside the family context including friends, peers, and romantic partners. It therefore appears important to investigate the neural basis of attachment and attachment orientations during adolescence to better understand the underlying brain mechanisms.

FIGURE_1In a first fMRI study of this kind, we looked at brain activations to congruent versus incongruent social feedback processing in 33 healthy adolescents (aged 12 to 19) as a function of their age, sex, and attachment style. The corresponding paper is published and is freely available here.

Our results showed that attachment avoidance appears to influence brain activity during social feedback processing in the opposite direction of observed “normal” developmental effects. In other words, whereas increasing age seemed to be associated with a tendency to more strongly process incongruent social feedback, attachment avoidance appeared to show an inverse activation pattern – that is, a stronger focus on congruent social feedback. Our findings therefore suggest that attachment avoidance may incur less mature processing of social feedback during adolescence. High attachment avoidance may thus preclude the usually observed “opening up” to social information in terms of social sensitivity in the course of adolescent development. What is concerning attachment anxiety, observed effects were comparable with activation patterns related to age – that is, increased brain activity during incongruent social feedback processing. Because such attachment anxiety effects remained significant when controlling for age, our findings suggest that attachment anxiety may be associated with a stronger focus on incongruent social feedback processing representing social conflict more generally. Some implications of the above described findings are discussed in my blog on Attachment Style and Brain Activity in Adolescents.

slide1In a second fMRI study, we investigated the neural basis of self- versus other-perception in 44 healthy adolescents (aged 12 to 19) as a function of their attachment-derived internal self- and other-working models (IWMs). Attachment theory suggests that, through IWMs, attachment security and insecurity is associated with distinct representations of the self and others. Attachment security is usually characterized by positive self- and other-models. In turn, attachment insecurity is normally linked to disturbed self- and other-representations. More specifically, attachment avoidance is associated with an overly positive self- but a negative other-view, whereas attachment anxiety is linked to a more ambivalent self- and other representation. However, how such disturbed self- and other-views associated with attachment insecurity relate to brain activity during social emotional processing remains largely unknown. The corresponding paper is published and freely available here.

Our data revealed that participants with a more negative attachment-derived self-
model showed increased brain activity during positive and negative adjective evaluation regarding the self, but decreased brain activity during negative adjective evaluation regarding a close other, in bilateral amygdala/parahippocampus, bilateral anterior temporal pole/anterior superior temporal gyrus, and left dorsolateral prefrontal cortex. These findings suggest that a low positivity of the self-concept characteristic for the attachment anxiety dimension may influence neural information processing, but in opposite directions when it comes to self- versus (close) other-representations. We discuss our results in the framework of attachment theory and regarding their implication especially for adolescent social-emotional development and social integration.


5) The Neural Substrates of Attachment in Children

While the literature on the neural basis of attachment and attachment orientations in adults is steadily growing and first findings on the same mechanisms in adolescents are starting to emerge (see above), it remains largely unknown how individual differences in attachment influence brain activation in children. For example, nice research by Lane Strathearn et al. (see here and here) showed that mothers’ brain responses to images of own (versus unknown) children can be importantly altered by attachment insecurity – particularly attachment avoidance. However, there is no literature available yet on how an avoidant and/or anxious attachment orientation may influence brain responses in children themselves.

In order to close this gap, I have started a new line of research in collaboration with the CIBSR at Stanford University in children aged 8 to 12, and with the University of Vienna and MPI CBS Leipzig in children aged 5, to directly examine the neural basis of attachment behavior and attachment orientations at this early developmental stage. Experiments include both fMRI and fNIRS (see below) scans in girls and boys.

To obtain a comprehensive picture of attachment patterns in families, we also include measures provided from children’s parents, and performed fNRIS scans in child-mother dyads (i.e., hyperscanning – see below). A new study with father-child pairs has been approved for the year 2018.

We hope that our research in children and families will ultimately allow for the development of new early prevention and intervention strategies (see also here).

More details will be provided here as soon as the results of our research in children, child-mother dyads, child-father dyads, and families become available.


6) Attachment & Bio-Behavioral Synchrony in Adult Dyads and Child-Mother/-Father Dyads

Attachment is a social process from the very beginning. Therefore, besides looking at the neural basis of attachment and attachment orientations in single person experiments, I am now also moving to so called hyperscanning experiments where behavioral performance and brain activity are assessed in two people at the same time. This allows for measuring bio-behavioral synchrony between individuals as a proxy for their social connectedness.

In a first part of this project, I am currently looking at bio-behavioral synchrony between (young) adult participants while they perform different collaborative, competitive, and independent versions of a reaction time task (for a previous publication using the same task, see here).

In a second part of this project, I will be looking at the same task in 8-12 year old children and their mothers.

I am furthermore co-supervising a Master’s thesis project on bio-behavioral synchrony between 5-year old children and their mothers during a collaborative puzzle-solving task, here as a function of mother’s attachment orientation and child temperament. A new study looking at bio-behavioral synchrony in father-child pairs (child age again 5 years) as a function of both child and father attachment orientation will be conducted during the year 2018 as well. 

More details will be provided here as soon as the results  of the above projects become available.


7) The Genetics and Epigenetics of Attachment

Through international collaborations, I am also able to investigate the genetic and epigenetic correlates of attachment in (young healthy) adults. Inter-individual differences in attachment can be understood as meaningful adaptations to  specific environments, and their emergence therefore to represent a prototypical gene x environment interaction process. By looking at the genetic information in addition to epigenetic markers (i.e. methylation controlling the transcription of genes), we hope to obtain a better insight into the biological mechanisms underlying the environmental adaptations characterizing attachment, and in particular secure versus insecure, avoidant and/or anxious attachment orientations.

rahd_a_1446451_f0002_bIn a first paper, we looked at epigenetic modification (degree of methylation) of the oxytocin receptor gene (OXTR) and glucocorticoid receptor gene (NR3C1) promoters as a function of self-reported attachment avoidance and anxiety in a sample of 109 young healthy adolescents. The paper is published and freely available here.  

Our findings revealed a specific association between the degree of both OXTR and NR3C1 promoter methylation and attachment avoidance (i.e. in participants who scored high on attachment avoidance but low on attachment anxiety). Attachment avoidance may thus be epigenetically characterized by a less active oxytocin system generally thought to be implicated in prosocial processes also comprising mechanisms to cope with stress by seeking proximity to and comfort by others. In addition, attachment avoidance may also be characterized by a more active HPA axis and thus sustained stress, because the glucocorticoid receptor NR3C1 is generally associated with the negative feedback-loop of the HPA axis to shut down the stress response. This may be due to the fact that avoidantly attached individuals tend to be self-reliant and do less likely turn to others to help them (co-)regulating stress, which may be a less effective / more costly stress-regulation strategy.

More research in this exciting and new field of research are needed, also comprising replication and extension of the results we obtained in our first study reported above. Please stay tuned for more information about this project, which will be provided here once it becomes available.


For additional information on my attachment research, please refer to the Publications page where the above described papers and book chapters are available for download. You can also contact me with any questions.