Tag Archives: Research

Applying the Evolutionary Science of Attachment Bonds

Attachment theory is one of the most enduring theoretical frameworks in psychology, spanning the areas of developmental psychology, social/personality psychology, and evolutionary psychology. Broadly, classical attachment theory, originally developed by John Bowlby, focuses on the development of attachment bonds between parents and infants, and how those early attachments influence social development throughout childhood and into adolescence, coalescing in adult romantic attachments.

During my doctoral studies I became interested in attachment utilizing an evolutionary framework after reading a classic (monster of a) paper from Dr. Marco Del Giudice. I was fascinated with questions of the functional nature of adult attachments: What purpose did pair-bonding and romantic attachments serve in adults? What was the relationship between romantic attachments and the diversity of sexual strategies in humans? In what ways are romantic attachment similar, and different, from infant attachments?

I began exploring these questions about attachment intensely, and for my comprehensive exams to advance to candidacy I wrote a novel theoretical framework for understanding the evolution and development of attachment systems. I am currently working on refining this framework to publish in a series of papers.

The first of this trilogy, The Nature of Attachment Systems, has just been accepted for publication in Social and Personality Psychology Compass. The primary thesis of this paper is that infant and adult attachments are fundamentally different in nature; that is, their evolutionary history, operation in social contexts, and functions are different. This diverges from classical attachment theory by way of proposing that what we commonly think of as “attachment” is comprised of two distinct evoled cognitive systems, rather than one as proposed by classical interpretations of attachment theory.

One hypothesis that I propose in this paper is the Mate Guarding Hypothesis of attachment, which states:

Once pair-bonding and consequent attachments are established, mate guarding ensures the optimization of resource investment for both males and females. Here, I propose that mate guarding is the primary manifestation of the romantic attachment system, whereby romantic attachment bonds are a primary motivational source underlying mate guarding behaviors. Mate guarding behavior occurs in response to threats to the pair-bonded relationship. Threats can be exogenous in origin (intrasexual competitors), or endogenous in origin (emotional detachment or disinterest of mate). Threats may be acute in nature (a present, intrasexual competitor), ongoing (chronic jealousy), or perceived (suspicion of partner’s activities). Threats to a pair-bonded relationship can thus be operationalized as endogenous or exogenous threats to the stability of the pair-bond that negatively affect optimal investment of resources into the mateship, for either partner. The romantic attachment system, then, is a suite of psychological mechanisms that primarily operate to prevent, correct, and address threats to the pair-bond most often by regulating mate guarding behavior, broadly construed.

Barbaro, in press, pp. 10-11.

This hypothesis follows from a line of empirical work that I have been leading since 2016 on the associations between attachment orientations, particularly anxiety (which is characterized by hyper-activation of the attachment system), and mate guarding outcomes (see here and here).

Essentially, what we understand to be mate guarding behaviors — that have been heavily researched by evolutionary psychologists — are a primary manifestation of the romantic attachment system, which actively monitors threats to one’s pair-bond (see figure). Why is this important? Because pair-bonded relationships are reliant on heavy resource investment from both parties. And, particularly for males, is quite divergent from the classical “promiscuous male” mating strategy that dominates the male mammalian kingdom. There is a reason that pair-bonding is rare among mammals — it’s got to be worth the time (evolutionarily speaking).

Conceptual depiction of the Mate Guarding Hypothesis of Romantic Attachment based on Barbaro, in press.

Okay, so why is any of this important? Because understanding how our mind monitors threats our romantic relationship can help us be more self-aware and understanding of our own (and our partner’s) behaviors within our relationship. Recently, Dr. Michael Bailey asked me to briefly discuss ways in which evolutionary psychology can be applied to our lives. What I shared with him (and his psychology class via video), touches on my recent attachment work, especially with regard to the mate guarding hypothesis. Below is the 12 minute clip (shared with permission).

Although I am obviously biased, I find the notion that your attachment bond and its manifestations within your relationship are strongly influenced, in part, by the relationship dynamics within that relationship context far more appealing than the still popular proposition that your early relationships with your parents set the course for your adult romantic relationships — but that’s a topic for the next paper…

Questioning the Role of Menarche Timing in Life History Models of Sexual Development

Life history models of sexual development are popular for understanding female sexual development as it relates to early experiences in the rearing environment. Broadly speaking, life history models suppose that early stressful environments will lead to accelerated maturation, manifesting as earlier timing of menarche, which subsequently leads to earlier age at first sex, and more unrestricted (and risky) sexual behavior.

Although there are subtle differences between the three primary life history developmental models (see Figure 1 for a conceptual depiction of predictions across the three models), they all have in common the prediction that menarche timing is, in part, regulated by early environmental stress, such that stress and father absence – a particular variable of interest within the literature – predict earlier menarche timing.

Figure 1. Conceptual model of the theoretical predictions derived from various life history models of development. Solid lines indicate predicted association. PA = psychosocial acceleration theory; CD = child development theory; PI = paternal investment theory.

The effect of father absence on menarche timing has been enjoying a rich discussion in recent years, with criticisms ranging from genetic confounding (which my colleagues and I outline here) to WEIRD effects not found in cross-cultural data. Other criticisms have focused on the issue of broader confounding factors such as socioeconomic status and body mass index. Although each of these criticisms and alternative explanations for menarche timing have been investigated independently in previous research, no previous study has attempted to comprehensively evaluate a broad array of proposed effects of life history antecedents on menarche timing (that are derived from life history developmental models) with a genetically informative research design.

In our recent research, we (co-authors, George Richardson, Joe Nedelec, & Hexuan Lui) sought to test a comprehensive model of theoretically relevant life history predictors on menarche timing and subsequent sexual behavior in girls using a twin subsample from Add Health. We took a two-stage approach to test the associations between father absence, specifically, and environmental stress, broadly, with age at menarche and sexual debut, and to identify potential genetic confounding of those associations.

In the first stage we tested and refined a measurement model specifying a latent environmental stress factor, and then built and tested a comprehensive structural equation model to test our life history hypotheses (see Figure 2). What is most striking about these results is what effects are not detected. There are no significant effects of environmental stress or father absence on age at menarche; only BMI is a significant predictor (a well-known predictor in the pediatrics literature.) There were, however, significant effects of early environmental stress on sexual debut, consistent with recent work in a Canadian sample.

Figure 2. Final SEM model. Only significant effects show.

In the next stage, we used univariate and multivariate behavior genetic models to identify whether significant associations between BMI and age at menarche, and between age at sexual debut and number of sexual partners and risky sexual behavior, were confounded by shared genetic covariation. Results here did not provide evidence of a nonshared environmental association (i.e., an association that survived control of genetic and shared environmental factors), suggesting the effect of BMI on age at menarche in our nongenetically informative model is likely spurious. Findings also did not provide evidence of a nonshared environmental association between age at sexual debut and risky sexual behavior. However, the association between age at sexual debut and number of sexual partners did survive control of genetic and shared environmental factors, suggesting it may reflect a causal effect of the former on the latter.

This study tested many other predictions in addition to the key findings presented above. Below in Table 1 is the tl;dr version of our primary aims and results summary.

Table 1. tl;dr summary of research aims and results.

What do all these results mean for life history models of sexual development? First, and in my view, most importantly, is that the null association between early environmental stress and father absence with menarche timing (the latest null result in a growing list) calls into question each of the three life history developmental models. Why? Because parental investment theory, psychosocial acceleration theory, and child development theory all rely on menarche timing as a key regulatory mechanism linking early environments to adolescent sexual behavior. (In our paper we discuss at great length the implications for each theory on preprint pp. 20-23).

Our behavior genetic models offer some interesting insights to life history models, too – just not for age at menarche. The evidence associated with age at sexual debut does suggest sexual behavior may be, in part, responsive to early environmental stress. Unlike age at menarche, age at sexual debut does reflect the shared environment in all the models we tested. Again, however, life history developmental models will have to reconcile the fact that the key regulatory mechanism of menarche timing is missing. Additionally, these results also do not provide evidence for my own hypothesis that the association between father absence and age at menarche is genetically confounded – because there appears to be no such association to confound!

This paper, currently under peer-review, contributes to the ongoing critical discussions in the life history literature particularly regarding developmental models, facultative adjustment, and genetic confounding. We look forward to hearing your comments!

Preprint (19 June 2020)

OSF project and pre-registration

Open Science as a Solution for Rigorous and Impactful EdTech Research

High quality research is the foundation from which effective and impactful EdTech is built on. Educators, institutions of learning, and companies depend on research to make informed decisions about what products and interventions to implement. There is, of course, some responsibility on those choosing products to do their due diligence on the research backing such products. But, on the other hand, the greater responsibility should fall on the companies and researchers conducting studies.

Why is research so important? Because we want to know what actually helps students and the impact that EdTech products are having on our populations of focus. If EdTech is interested in building long-term, effective, and sustainable solutions to drive innovation, then credible and rigorous research is essential to accomplish these goals.

Our research practices and policies at WGU Labs were designed to ensure that the research we’re doing on EdTech products and educational interventions is rigorous, transparent, and impactful. There are three problems that EdTech focused companies, especially those like WGU Labs that also work with third-party EdTech products, must solve to produce rigorous research:

  1. The Research Problem
  2. The Credibility Problem
  3. The Accessibility Problem

This post appeared on WGU Labs’s blog on 15 April 2020. Click here to continue reading.