Thursday, August 26, 2021

Notable sex differences in autonomic functioning among trauma-exposed individuals: A prospective examination

A prospective examination of sex differences in posttraumatic autonomic functioning. Antonia V. Seligowski et al. Neurobiology of Stress, Volume 15, November 2021, 100384.


Background: Cross-sectional studies have found that individuals with posttraumatic stress disorder (PTSD) exhibit deficits in autonomic functioning. While PTSD rates are twice as high in women compared to men, sex differences in autonomic functioning are relatively unknown among trauma-exposed populations. The current study used a prospective design to examine sex differences in posttraumatic autonomic functioning.

Methods: 192 participants were recruited from emergency departments following trauma exposure (Mean age = 35.88, 68.2% female). Skin conductance was measured in the emergency department; fear conditioning was completed two weeks later and included measures of blood pressure (BP), heart rate (HR), and high frequency heart rate variability (HF-HRV). PTSD symptoms were assessed 8 weeks after trauma.

Results: 2-week systolic BP was significantly higher in men, while 2-week HR was significantly higher in women, and a sex by PTSD interaction suggested that women who developed PTSD demonstrated the highest HR levels. Two-week HF-HRV was significantly lower in women, and a sex by PTSD interaction suggested that women with PTSD demonstrated the lowest HF-HRV levels. Skin conductance response in the emergency department was associated with 2-week HR and HF-HRV only among women who developed PTSD.

Conclusions: Our results indicate that there are notable sex differences in autonomic functioning among trauma-exposed individuals. Differences in sympathetic biomarkers (BP and HR) may have implications for cardiovascular disease risk given that sympathetic arousal is a mechanism implicated in this risk among PTSD populations. Future research examining differential pathways between PTSD and cardiovascular risk among men versus women is warranted.

Keywords: TraumaPTSDAutonomicSexCardiovascular

5. Discussion

This study used a prospective design to examine sex differences in autonomic functioning among a sample of recently traumatized men and women. Sex differences were observed and varied by biomarker. While men demonstrated significantly higher BP and rates of hypertension, women demonstrated significantly higher HR and lower HF-HRV, and these effects were strongest among women who subsequently developed PTSD. Further, acute sympathetic arousal (indexed via skin conductance response) associated with HR and HF-HRV during fear conditioning but only among women who developed PTSD.

Our findings regarding BP and hypertension are consistent with what is commonly observed in the general population, such that men are more likely than women to experience hypertension (American Heart Association, This sex difference is known to decrease among older age groups and it is thought that decreasing estradiol levels as a result of menopause in women play a role (i.e., estradiol is cardioprotective and may explain lower rates of hypertension in pre-menopausal women; for reviews, see Colafella and Denton, 2018Regitz-Zagrosek et al., 2016). It is important to note that the average age in our sample was 35 and thus most women were pre-menopausal. While prior studies have found that individuals with PTSD demonstrate higher BP than those without PTSD (for a review, see Buckley and Kaloupek, 2001), we did not observe an effect of PTSD status. One potential explanation is that our sample is not as highly traumatized as comparisons in prior work (e.g., most participants were in motor vehicle collisions). Similarly, BP was assessed with only one measurement and this occurred two weeks following trauma exposure. It is therefore possible that the higher levels of BP observed in prior PTSD studies were a result of more chronic PTSD symptoms and sympathetic hyperarousal, which our study did not capture.

In terms of HR and HF-HRV, our findings indicate that women experienced worse autonomic functioning during fear conditioning compared to men, and this was particularly seen in those women who subsequently developed PTSD. Specifically, trauma-exposed women demonstrated stronger sympathetic arousal and worse parasympathetic control than men during fear learning, where main effects of sex were observed, and those with PTSD demonstrated particularly worse functioning during extinction. This is consistent with prior literature implicating extinction deficits as a biomarker specific to PTSD (Jovanovic et al., 2012) and further suggests that women may be more likely than men to experience these deficits. Given that HF-HRV has been shown to be higher in healthy women compared to men (for a review, see Koenig and Thayer, 2016), our findings also highlight the importance of trauma and PTSD status in sex differences in autonomic function. The lack of sex differences in eyeblink startle (a brainstem-mediated reflex and not an autonomic indicator) suggests that there may be specificity of our sex-based findings to peripheral autonomic and cardiovascular physiology (i.e., HR and HF-HRV). Additionally, low levels of estradiol have been implicated as a contributing factor to fear inhibition and extinction deficits in women with PTSD (indexed via eyeblink startle; Glover et al., 20122013) as well as healthy controls (indexed via skin conductance; Milad et al., 2010). Thus, future research is needed to determine if an interaction between PTSD status and high versus low estradiol confers greater risk for autonomic and inhibition/extinction deficits (indexed via startle) in trauma-exposed women.

eSense has previously demonstrated utility in predicting PTSD status and symptom trajectory when used to measure skin conductance in recently traumatized individuals in emergency departments (Hinrichs et al., 2019). Our findings suggest it may have additional, and perhaps more specific utility among women, such that eSense skin conductance levels were significantly associated with future HR and HF-HRV only in women who developed PTSD. Given that autonomic deficits have been implicated in the increased risk of cardiovascular disease in PTSD, future research testing eSense as a predictor of autonomic functioning and subsequent cardiac events could be extremely useful in determining which trauma-exposed individuals are at highest risk for developing cardiovascular disease. Findings from the current study indicate that this may be a particularly useful tool among women, though replication is needed.

Our findings regarding sex differences in autonomic functioning may have clinical implications. Specifically, men and women differed in their sympathetic arousal, with men demonstrating higher BP and women demonstrating higher HR. Further, women demonstrated lower parasympathetic function than men. As mentioned above, autonomic deficits have been implicated in the increased risk of cardiovascular disease in PTSD. Our findings suggest that the specific autonomic mechanisms through which cardiovascular disease develops could differ for men versus women with PTSD. For example, there is preliminary evidence that blockade of the renin-angiotensin system (responsible for BP regulation) via ace-inhibitors and angiotensin receptor blockers is associated with decreased likelihood of PTSD diagnosis (Khoury et al., 2012Seligowski et al., 2021). We recently observed a sex effect such that the protective effects of these medications may be greater among men versus women (Seligowski et al., 2021). Thus, medications targeting BP may be more effective in men versus women with PTSD because men are more likely to experience hypertension and therefore see an effect of such medications. Prospective trials of antihypertensive medications for PTSD are needed to further explore sex differences in their effects. Another possible avenue for future trials is to determine if the autonomic deficits we observed during extinction in women with PTSD translate to clinical outcomes (e.g., do women with PTSD experience less symptom reduction from exposure treatments than men?). Thus far, sex differences in exposure-based treatments have not been reported, but we are not aware of any trials that examined sex differences in autonomic functioning during these treatments.

While capturing acute trauma reactions with a prospective design is a strength of this study, an important limitation is that our sample is not as highly symptomatic as comparisons from the literature. For example, we did not see main effects of PTSD status on BP, HR, of HF-HRV and this may be due to the recency of trauma exposure and the absence of severe PTSD symptoms in this cohort. Another limitation relates to trauma type, such that the index trauma for most participants was a motor vehicle collision and the incidence of PTSD in that population is lower than that of other trauma types, such as interpersonal violence and combat exposure (Kessler et al., 2017). Additionally, while we used a recommended cutoff for provisional PTSD diagnosis (Bovin et al., 2016) at 8-weeks, the current study relied on self-reported symptoms and did not include a structured clinical interview of PTSD. Future studies with more robust PTSD assessment among individuals with a broader range of trauma exposure will be needed to replicate and extend our findings. Despite these limitations, this study adds to a very scant literature regarding both 1) prospective assessments of posttraumatic autonomic functioning and 2) sex differences in posttraumatic autonomic functioning.

The current study identified sex differences in multiple domains of autonomic functioning among a recently traumatized sample. Our findings suggest that men and women demonstrate different patterns of sympathetic arousal, with men exhibiting higher BP and women exhibiting higher HR. Women also exhibited worse parasympathetic function as indicated by lower HF-HRV during fear conditioning, as was particularly seen in women who developed PTSD. Acute sympathetic arousal indexed by skin conductance in the emergency department was associated with HR and HF-HRV among women who developed PTSD, suggesting it may be a useful biomarker of subsequent autonomic functioning in this population. Additional studies examining subsequent sex differences in cardiovascular risk as a result of differential autonomic mechanisms are warranted.

Consumers Believe That Products Work Better for Others... including that medical products, social distancing against COVID-19, and SARS-CoV-2 vaccines

Consumers Believe That Products Work Better for Others. Evan Polman, Ignazio Ziano, Kaiyang Wu, Anneleen Van Kerckhove. Journal of Consumer Research, ucab048, August 18 2021.

Abstract: Consumers tend to see themselves in a positive light, yet we present evidence that they are pessimistic about whether they will receive a product’s benefits. In 15 studies (N = 6,547; including nine pre-registered), we found that consumers believe that product efficacy is higher for others than it is for themselves. For example, consumers believe that consuming an adult coloring book (to inspire creativity), a sports drink (to satisfy thirst), medicine (to relieve pain), or an online class (to learn something new) will have a greater effect on others than on themselves. We show that this bias holds across many kinds of products and judgment-targets, and inversely correlates with factors such as product familiarity, product usefulness, and relationship closeness with judgment-targets. Moreover, we find this bias stems from consumers’ beliefs they are more unique and less malleable than others, and that it alters the choices people make for others. We conclude by discussing implications for research on gift-giving, advice-giving, usership, and interpersonal social, health, and financial choices.

Keywords: perceived product efficacy, self-other differences, stimulus sampling, linear mixed effects modeling, perceived uniqueness, perceived malleability

After finding they were right, participants could send a neutral message or a message that included "I told you so"; most participants sent, at least once, "I told you so," despite not liking hearing that statement themselves

Impression (Mis)Management: When What You Say Is Not What They Hear. Ovul Sezer. Current Opinion in Psychology, August 26 2021.

Abstract: Impression management is a fundamental aspect of social life. From self-promotion to feedback giving, from advice-seeking to networking, people frequently find themselves in situations where they need to make a positive impression on others. Despite the long-term benefits of making a favorable impression, impression-management attempts can backfire in unintended ways. In this article, I review recent research on self-presentation, social cognition, and communication to explain when and why people have misguided intuitions about their impressions on others, document common impression-management mistakes, and propose more effective strategies to minimize actor-target asymmetries in social interactions. This review provides a theoretical framework to understand the psychology of impression (mis)management, as well as the risks and rewards of different self-presentation strategies.

Comments on Secretary Blinken's words... If the Taliban behave well enough, "that’s a government we can work with"

Secretary Blinken: If the Taliban behave well enough, "that’s a government we can work with". A friend's note, sent to Sec Blinken, Aug 26 2021, after his comments.

Mr Secretary, in a press conference you said: "But fundamentally, the nature of that engagement and the nature of any relationship depends entirely on the actions and conduct of the Taliban.  If a future government upholds the basic rights of the Afghan people, if it makes good on its commitments to ensure that Afghanistan cannot be used as a launching pad for terrorist attacks directed against us and our allies and partners, and in the first instance, if it makes good on its commitments to allow people who want to leave Afghanistan to leave, that’s a government we can work with.  If it doesn’t, we will make sure that we use every appropriate tool at our disposal to isolate that government, and as I said before, Afghanistan will be a pariah."

Just for your information, the twelfth report of a UN team, the Analytical Support and Sanctions Monitoring Team (established pursuant to resolution 1526 (2004)), submitted in July 2021 a report to the Security Council Committee established pursuant to resolution 1988 (2011), in accordance with paragraph (a) of the annex to resolution 2557 (2020), which says (notes deleted), pp 13-14:

"47. The killing of several Al-Qaida commanders in Taliban-controlled territory underscores the closeness of the two groups. Following the death of al-Rauf in October, the Al-Qaida in the Indian Subcontinent deputy, Mohammad Hanif (alias Abdullah), was killed on 10 November 2020 in Bakwa District of Farah Province. According to a Member State, he had been providing bomb-making training to Taliban insurgents in that location. Both individuals appear to have been given shelter and protection by the Taliban. On 30 March 2021, Afghan Forces led a raid in Gyan District of Paktika Province that killed a prominent Al-Qaida in the Indian Subcontinent commander, Dawlat Bek Tajiki (alias Abu Mohammad al-Tajiki), alongside Hazrat Ali, a Taliban commander from Waziristan.

"48. Al-Qaida’s presence in Afghanistan has also been confirmed by its own affiliated propaganda and media wings. Al-Qaida’s weekly Thabat newsletter reported on Al-Qaida operations inside Afghanistan, listing Al-Qaida attacks since 2020 in 18 provinces."

Also, it says, p 12: "42. According to Member State information, Al-Qaida is resident in at least 15 Afghan provinces, primarily in the east, southern and south-eastern regions. [...]"


Some people around the world report they would choose a psychologically rich life at the expense of a happy/meaningful life, and that approx 1/3 say that undoing their life’s biggest regret would have made their lives psychologically richer

Oishi, S., & Westgate, E. C. (2021). A psychologically rich life: Beyond happiness and meaning. Psychological Review, Aug 2021.

Abstract: Psychological science has typically conceptualized a good life in terms of either hedonic or eudaimonic well-being. We propose that psychological richness is another, neglected aspect of what people consider a good life. Unlike happy or meaningful lives, psychologically rich lives are best characterized by a variety of interesting and perspective-changing experiences. We present empirical evidence that happiness, meaning, and psychological richness are related but distinct and desirable aspects of a good life, with unique causes and correlates. In doing so, we show that a nontrivial number of people around the world report they would choose a psychologically rich life at the expense of a happy or meaningful life, and that approximately a third say that undoing their life’s biggest regret would have made their lives psychologically richer. Furthermore, we propose that the predictors of a psychologically rich life are different from those of a happy life or a meaningful life, and report evidence suggesting that people leading psychologically rich lives tend to be more curious, think more holistically, and lean more politically liberal. Together, this work moves us beyond the dichotomy of hedonic versus eudaimonic well-being, and lays the foundation for the study of psychological richness as another dimension of a good life.

Popular version: A 'Good' Life Doesn't Necessarily Have to Be Happy, New Psychology Research Shows (

Some highly satisfied individuals were also more likely to have engaged in infidelity, suggesting a more complex relationship between relationship satisfaction and infidelity

Is Infidelity Predictable? Using Explainable Machine Learning to Identify the Most Important Predictors of Infidelity. Laura M. Vowels, Matthew J. Vowels & Kristen P. Mark. The Journal of Sex Research, Aug 25 2021.

Abstract: Infidelity can be a disruptive event in a romantic relationship with a devastating impact on both partners’ well-being. Thus, there are benefits to identifying factors that can explain or predict infidelity, but prior research has not utilized methods that would provide the relative importance of each predictor. We used a machine learning algorithm, random forest (a type of interpretable highly non-linear decision tree), to predict in-person and online infidelity across two studies (one individual and one dyadic, N = 1,295). We also used a game theoretic explanation technique, Shapley values, which allowed us to estimate the effect size of each predictor variable on infidelity. The present study showed that infidelity was somewhat predictable overall and interpersonal factors such as relationship satisfaction, love, desire, and relationship length were the most predictive of online and in person infidelity. The results suggest that addressing relationship difficulties early in the relationship may help prevent infidelity.


Infidelity is relatively common, with up to half of those in relationships having engaged in infidelity (Mark & Haus, 2019; Mark et al., 2011; Thompson & O’Sullivan, 2016) with potentially devastating consequences for relationships causing distress (Thompson & O’Sullivan, 2016) and often divorce (Amato & Previti, 2004). Infidelity is likely to affect not only the couple members but also their children, extended family, and friends. It is important to identify potential risk factors for infidelity to target interventions that could prevent infidelity from occurring in the first place. The purpose of the present study was to identify potential factors associated with infidelity and to quantify and compare different factors to better understand which variables are the most strongly associated with infidelity.

A large body of literature has attempted to identify which factors contribute to infidelity. However, the studies have relied exclusively on linear models, which are often completely uninterpretable due to problems such as incorrect specification of the underlying causal structure, multicollinearity, unattainable parametric assumptions, and inability to examine complex associations (Breiman, 2001a; Lundberg et al., 2020; Yarkoni & Westfall, 2017). The present study is the first of its kind to examine predictors of infidelity using interpretable predictive models: random forests (Breiman, 2001b) with Shapley values (Lundberg et al., 20172019). Based on our findings, the short answer to the question posed in the title, “is infidelity predictable?,” is somewhat. The effect sizes that consider the true and false positives and negatives of both classes ranged between small (.18) to large effect (.49) across analyses and samples suggesting that even though we were able to predict infidelity generally well above chance level, there are also other factors that we had not accounted for.

The Comparison of Predictors of Infidelity

While we examined the predictive accuracy of our models, our main aim was to compare a range of different factors in their ability to predict infidelity. A recent systematic review found that while demographics and individual characteristics are inconsistently associated with infidelity, relationship variables tend to be more consistent across studies (Haseli et al., 2019). We also found that relationship characteristics (relationship satisfaction, relationship length, dyadic desire, sexual satisfaction, romantic love, and some sexual activities within the relationship) were consistently in the top-10 most important predictors across different samples. These findings suggest that addressing relationship issues may buffer against the likelihood of one partner going out of the relationship to seek fulfillment. However, it is also important to note that while individuals who were more satisfied in their relationship were generally less likely to engage in infidelity, a subsample of highly satisfied individuals had engaged in infidelity in the past. This may either reflect the idea that infidelity does also occur in happy relationships (Perel, 2017) or perhaps couples have worked through the infidelity and by the time they responded to the survey were satisfied in their relationship (Olson et al., 2002).

Furthermore, because online infidelity has become more commonplace given the technological advances in recent years (Albright, 2008), we also examined predictors of online infidelity. Interestingly, one of the strongest predictors of a decreased likelihood of having engaged in infidelity online was never having had anal sex in the present relationship. This may reflect more restrictive attitudes toward sexuality overall. Indeed, attitudes toward sexuality were measured in Study 1 and ranked among the Top-10 predictors of online infidelity. However, the relationship was more complex, with the most liberal sexual attitudes predicting an increase in likelihood of having engaged in infidelity whereas more moderate and conservative attitudes predicted a decrease. These results are in line with other studies that have found that more permissive sexual attitudes have been associated with an increased likelihood of having engaged in infidelity (Fincham & May, 2017; Haseli et al., 2019; Martins et al., 2016). Higher relationship length and sexual desire also increased the likelihood of having engaged in online infidelity. However, sexual and relationship satisfaction were only among the top predictors in one of the two samples.

The results of the present study corroborate many of the existing studies, and akin to a recent systematic review (Haseli et al., 2019), show that the most robust predictors of infidelity lie within the relationship: individuals who are more satisfied and in love in their relationship are less likely to have engaged in infidelity. There are also a number of factors that have previously been associated with infidelity that were not among the most important predictors in the present study: education (Atkins et al., 2001; Martins et al., 2016; Treas & Giesen, 2000), relationship status (Amato & Previti, 2004; Fincham & May, 2017), and attachment (Fincham & May, 2017; Haseli et al., 2019; McDaniel et al., 2017). We only examined attachment in Study 1 and higher attachment avoidance did predict an increased likelihood of having engaged in infidelity in the total sample but was not among the top-10 predictors for men or women. Attachment anxiety was not predictive of past infidelity. Furthermore, many previous studies suggest that men are more likely to engage in sexual infidelity than women (Labrecque & Whisman, 2017; Petersen & Hyde, 2010). In the present study, being a man was only an important predictor of past online infidelity in one sample, supporting studies that have found that the gender gap in infidelity is decreasing (Allen et al., 2006; Fincham & May, 2017; Mark et al., 2011; Treas & Giesen, 2000).

There were also some inconsistencies in the findings across the two samples. In Study 1, hormonal contraceptives decreased the likelihood of men having engaged in online infidelity whereas in Study 2 the use of hormonal contraceptives increased the likelihood of both men and women having engaged in online infidelity. The use of hormonal contraceptives does not prevent sexually transmitted infections and therefore increases the likelihood of passing any potential infections from the infidelity partner to the primary partner. This may deter people from engaging in infidelity face-to-face and instead seek alternative partners online. It is not clear why in one sample hormonal contraceptives increased the likelihood of engaging in infidelity and in another decreased it and the role of contraceptives on infidelity warrants further investigation. Furthermore, because each individual predictor only predicted very little variance in the outcome, interpreting each individual variable becomes more difficult. When the signal is stronger (i.e., a variable predicts a larger amount of variance) the prediction also becomes more accurate.

Implications for Theory and Future Research

The present study examined predictors of infidelity from the ecological theory perspective (Bronfenbrenner, 1994). Specifically, we tested the ECSD model from a recent systematic review that suggested that both partners’ individual as well as couple’s factors predict infidelity. We found little evidence to suggest that partner variables predicted actor’s engagement in infidelity. In fact, in some analyses the predictive accuracy of the models decreased as a result of including partner variables in the models, suggesting that adding partner factors in the models may add noise that makes it more difficult for the model to make accurate predictions. Additionally, the present study suggested that relationship-related variables contributed the most to the prediction. However, it is important to caveat these findings in that we were essentially predicting infidelity in the past from the present variables. Therefore, it is possible that couples in which infidelity had occurred had worked through the infidelity and were now happier in their relationship than before.

In addition to relational variables, variables that tapped into people’s attitudes were also predictive of both in person and online infidelity. Overall, having less permissive attitudes toward sexuality suggested a decreased likelihood of having engaged in infidelity. Individuals with highly liberal attitudes were the most likely to have engaged in infidelity in the past. Certain sexual behaviors such as the use of sex toys, anal sex, and masturbation with a partner may also have acted as a proxy for attitudes in the present study. Indeed, previous studies have suggested that sexual attitudes and behaviors go hand in hand (Lefkowitz et al., 2014). The results of the present study suggested that individuals who had not engaged in traditionally more permissive sexual behaviors such as using sex toys or having anal sex were less likely to also have engaged in infidelity. Most other individual variables were not consistently among the Top-10 predictors of infidelity, which may explain why the results from previous studies (Haseli et al., 2019; Mark & Haus, 2019) have been inconsistent, especially when examining socio-demographic variables.

Finally, the purpose of the present study was to examine a range of variables in their ability to predict infidelity. Overall, each variable alone predicted little variance in infidelity. Therefore, the results do not suggest that there is one single, or a few, variables that are highly predictive of infidelity. Instead, a large number of variables together resulted in the algorithm’s overall ability to predict infidelity with a moderate to large effect size. Relationship variables together explained the largest amount of variance in the predictions. Relationship variables, however, are more likely to vary over time compared to certain individual characteristics (such as socio-demographic variables or attachment style). The prediction accuracy may have increased if the infidelity and relationship quality had been measured closer in time. Therefore, future research is needed to examine recent infidelity to more fully understand how relationship characteristics relate to infidelity. Additionally, because each variable contributed little to the overall prediction accuracy, using machine learning models with a large number of variables instead of focusing on single variables for predicting infidelity may be more fruitful in being able to predict who has or will engage in infidelity. This does not help target-specific factors but may be used to identify individuals or relationships who may be at a higher risk.

Strengths and Limitations

The present study adds to our understanding of the most important predictors for infidelity across two samples. We used a powerful interpretable machine learning technique that allowed us to produce reliable estimates of the effect sizes of each variable both for the mean effect as well as the spread of the individual effects (Lundberg et al., 20172019). Using this method, we were also able to compare a large number of predictors simultaneously and estimate any non-linear associations and complex interactions. We also examined both in-person and online infidelity.

However, the study also had several limitations that should be considered. First, we used a single-item measure of in-person and online infidelity. We were thus unable to account for specific infidelity behaviors and did not examine emotional infidelity. Future research is needed to examine a wider range of infidelity behaviors to better understand whether the same predictors generalize across multiple forms of infidelity or whether these are predicted by different variables. The results from the present study suggest that these may be somewhat different given that the most important predictors of in-person and online infidelity also varied. Second, while we examined infidelity across two large samples with one sample including data from both members of the couple, the studies were all cross-sectional and it is not clear how recently the infidelity occurred. Therefore, some of the factors may have changed from when the infidelity occurred to when the participants completed the survey. This is a difficulty across most other studies on infidelity, but future research should examine infidelity over time or to conduct surveys on individuals who have just engaged in infidelity. Third, over 30% of the participants in Study 1 reported past infidelity. However, the number of participants who had engaged in infidelity in the dyadic sample was much lower. This made it more difficult for the algorithm to accurately predict infidelity which is reflected in lower precision and recall for the infidelity class compared to no infidelity. We used balanced random forests to mitigate this issue, but we still had less data available of people with past infidelity.

Furthermore, each variable contributed very little to the overall classification accuracy. Therefore, interpretation of the results may be less accurate than when individual variables have a clearer signal. Additionally, while random forests are a powerful tool that will take advantage of any correlations and interactions in the data, no matter how non-linear, it cannot be used to estimate causality. However, in the absence of a means to reliably estimate causality when examining factors relating to infidelity (after all we cannot create experiments in which we make people engage in infidelity), we believe that using a predictive model is perhaps the best option. Finally, we chose to use a random forest algorithm because of a moderate sample size. Random forests have been shown to perform well with their default settings without the need for hyperparameter tuning (Probst et al., 2019). Tuning hyperparameters requires a separate training set which would make the sample size in the test data smaller. However, there may be other algorithms that would perform better or similarly with hyperparameter tuning. Therefore, future research in larger samples could use different algorithms to compare the performance of different algorithms.

Sexuality, Sexual Behavior, and Relationships of Asexual Individuals: Differences Between Aromantic and Romantic Subtypes of Asexual Individuals

Carvalho, Ana C., and David L. Rodrigues. 2021. “Sexuality, Sexual Behavior, and Relationships of Asexual Individuals: Differences Between Aromantic and Romantic Orientation.” PsyArXiv. August 26. doi:10.31234/

Abstract: Asexuality is a complex construct with a considerable lack of research until recently. Building upon available findings, we examined the extent to which romantic orientation shapes individual and relationship experiences and expectations of asexual individuals. Specifically, our research focused on the distinction between romantic asexual individuals, who experience romantic attraction, and aromantic asexual individuals, who do not experience romantic attraction. A cross-sectional study with members of different asexual online communities (N = 447, 55.02% women; Mage = 24.77, SD = 7.21) aimed at examining how both groups differ in their identification with the asexuality construct as measured by the Asexuality Identification Scale (Yule et al., 2015), individual perspectives on sexuality, sexual behavior and relationships, concerns about commitment and sexual performance in a relationship, and attachment style. Results showed that aromantic asexual individuals identified more with asexuality, reported a more avoidant attachment style, and were more concerned with relationship commitment. In contrast, romantic asexual individuals reported less sex aversion, more sexual experiences (both past and current), and more sexual partners in the past. These individuals also indicated to have engaged in romantic relationships more frequently, desire to engage in romantic relationship in the future (either with or without sexual intimacy), and were more concerned with sexual performance. Overall, our findings contribute to the literature by highlighting the need to consider romantic orientation when examining asexuality and its interpersonal outcomes.

Topological measures for identifying and predicting the spread of complex contagions

Topological measures for identifying and predicting the spread of complex contagions. Douglas Guilbeault & Damon Centola. Nature Communications volume 12, Article number: 4430. Jul 20 2021.

Abstract: The standard measure of distance in social networks – average shortest path length – assumes a model of “simple” contagion, in which people only need exposure to influence from one peer to adopt the contagion. However, many social phenomena are “complex” contagions, for which people need exposure to multiple peers before they adopt. Here, we show that the classical measure of path length fails to define network connectedness and node centrality for complex contagions. Centrality measures and seeding strategies based on the classical definition of path length frequently misidentify the network features that are most effective for spreading complex contagions. To address these issues, we derive measures of complex path length and complex centrality, which significantly improve the capacity to identify the network structures and central individuals best suited for spreading complex contagions. We validate our theory using empirical data on the spread of a microfinance program in 43 rural Indian villages.


Path length is one of the most important and influential measures of network structure. It underlies nearly every theory of social connectedness, social distance, and social influence within social networks. Here we show that the classical measure of simple path length, upon which most popular measures of node centrality depend, implicitly assumes the spreading dynamics of simple contagion. This assumption has resulted in several puzzling empirical findings in which individuals with putatively low centrality have been shown to be more influential for diffusion than individuals with high centrality (according to prominent measures of degree centrality, betweenness centrality, eigenvector centrality, k-core centrality, and percolation centrality). We derive new topological definitions of bridge width, path length, and centrality, which provide general topological measures for accurately estimating the network properties of connectedness, distance, and centrality for the spread of complex social contagions. We find that these measures offer significant theoretical improvements over existing measures of population-level network topology, and individual-level node centrality, for predicting the network properties that will increase the spread of complex social contagions.

Our findings offer several noteworthy departures from the dominant strategies for applying network theory to problems of social diffusion1,3,5,29,42,43,44,45,46,47. First, a common assumption among both theoretical and applied studies of network diffusion is that people with more connections are more influential5,21,22,29,30,42,43,44,45. Our findings disagree with the frequently asserted claim in this literature that degree centrality is an effective, if approximate, means of identifying the most influential individuals within a social network, regardless of context5,21,22,29,30,42,43,44,45. Second, a common assumption within organizational studies of social networks is that information brokers—i.e., people who participate in multiple distinct network communities that are largely disconnected—have outsized influence because they are the gatekeepers in the flow of contagions between communities46,47. This assumption has resulted in betweenness centrality becoming one of the most widely used measures of network influence within organizational theory1,27,29,42,43,46,47,48,49. By contrast, our findings indicate that network locations with low degree centrality and low betweenness centrality may nevertheless be the most influential locations in the population. We also find that individuals with the highest levels of degree centrality and betweenness centrality typically occupy ineffective network positions for initiating the spread of complex social contagions—including health behaviors8,9, linguistic conventions6,12,13, political memes14, social movements15,16, and complementary technologies6,10. We anticipate that an important direction for future work will be the exploration of new algorithms for computing the theoretical properties of complex path length and complex centrality, which may benefit from recent developments that improve the scalability of novel algorithmic techniques50. Another interesting direction for future research is the application of our topological measures for identifying specific network locations that can be used to efficiently stop the spread of an existing complex contagion from one part of a network to the entire population (akin to the problem of network “immunization” for simple contagions)6,51,52.

Beetles: Rapid evolution of sexual size dimorphism facilitated by Y-linked genetic variance

Rapid evolution of sexual size dimorphism facilitated by Y-linked genetic variance. Philipp Kaufmann, Matthew E. Wolak, Arild Husby & Elina Immonen. Nature Ecology & Evolution, Aug 19 2021.

Abstract: Sexual dimorphism is ubiquitous in nature but its evolution is puzzling given that the mostly shared genome constrains independent evolution in the sexes. Sex differences should result from asymmetries between the sexes in selection or genetic variation but studies investigating both simultaneously are lacking. Here, we combine a quantitative genetic analysis of body size variation, partitioned into autosomal and sex chromosome contributions and ten generations of experimental evolution to dissect the evolution of sexual body size dimorphism in seed beetles (Callosobruchus maculatus) subjected to sexually antagonistic or sex-limited selection. Female additive genetic variance (VA) was primarily linked to autosomes, exhibiting a strong intersexual genetic correlation with males (ram,f = 0.926), while X- and Y-linked genes further contributed to the male VA and X-linked genes contributed to female dominance variance. Consistent with these estimates, sexual body size dimorphism did not evolve in response to female-limited selection but evolved by 30–50% under male-limited and sexually antagonistic selection. Remarkably, Y-linked variance alone could change dimorphism by 30%, despite the C. maculatus Y chromosome being small and heterochromatic. Our results demonstrate how the potential for sexual dimorphism to evolve depends on both its underlying genetic basis and the nature of sex-specific selection.

The effects of alpha male removal on the social behavior of a group of olive baboons: Females seem to respond to male removal showing a more affiliative and tolerant behavior

The effects of alpha male removal on the social behavior of a group of olive baboons (Papio anubis). Ester Orient & Federico Guillén-Salazar. Journal of Applied Animal Welfare Science, Aug 26 2021.

Abstract: In captivity, the managers of primate populations have removed individuals from their groups for medical and social reasons, but there has been little documentation regarding the consequences of this extraction on the sociality of the remaining individuals. This study provides information about the social effect of the alpha male removal in a group of olive baboons (Papio anubis) maintained at the Station of Primatology of CNRS (France). Data on social behavior was collected before and after male removal and then compared. Moreover, this social information was used to calculate the individual dominance index and the group dominance ranking. Overall, our results indicate that females seem to respond to male removal showing a more affiliative and tolerant behavior. However, the results also highlight the different coping mechanisms of females with this new social context. Therefore, this information could be useful for managers of primate populations, allowing them to anticipate the response of captive groups when facing certain sociodemographic changes. In this regard, we recommended creating a detailed procedure before the removal of the individuals that considers the characteristics of the individuals.

KEYWORDS: Male removalolive baboon (Papio anubis)small groupssocial behavior


The results presented here show how after male removal half of the dyads increased their grooming. Moreover, the females displayed a less aggressive behavior in general terms, especially to one of the most subordinate females, and a more tolerant behavior toward the most dominant female (decreas^Bing their retreats). The social scenario after male removal therefore seems to be close to a peaceful scenario, in which females try to increase the strength of their social bonds.

The increase of the affiliative interactions observed in females are consistent with the results obtained by Chowdhury and Swedell (2017) after the male’s death in a group of chacma baboons.

However, while these authors observed that all females invested more time in grooming, we only observed the increase of the interactions in half of them. In this sense, Chism & Rogers (2002) suggest that the removal of individuals may be disruptive to the relationships of certain animals, but not in others, as observed in this study. They also claim that interactions are established between real individuals, with their own characteristics (e.g., personality, experience) and not between theoretical categories of individuals.  Our results partially agree with the description made by authors such as Keddy-Hector and Raleigh (1992) or Lemasson et al. (2005) after alpha removals, because they state that the remaining individuals increase both affiliative and aggressive interactions but, in this study, females only increased their grooming exchanges. Moreover, our results are totally opposite to those obtained by other authors who pointed out that animals become more aggressive after the removal of the alpha individual (Lowland gorilla: Hoff et al., 1982; Rhesus macaques: Judge et al., 1995; Common marmosets: Lazaro-Perea et al., 2000). As indicated previously, our females showed a more tolerant behavior after male removal, decreasing their mutual aggressions and their avoidance of the more dominant female.

Changes in the dominance hierarchy are a common outcome of the modification of the socio-demographic composition of a group [Japanese macaques (Macaca fuscatta): (Kawai, 1960; Nakamichi et al., 1995); Rhesus macaques: (Bernstein, 1964); Vervet monkeys: (Guy & Curnoe, 2011)]. After a social and demographic change, the remaining individuals try to cope with this period of social instability by re-organizing their previous relationships (Colmenares & Gomendio, 1988), which may result in a change dominance ranking. In this work, there has been a slight change in the female dominance ranking after the male removal, particularly in regard to the two females located in lower positions. This change in the agonistic behavior of these females leads to a partial modification in the dominance ranking. Therefore, our results agree partially with the idea of a social reorganization after a period of instability, stated by Colmenares and Gomendio (1988).

As pointed out by Lemasson et al. (2005), the social status of individuals and the species are determining factors in the effects of the removal of an individual. We suggest that the changes observed in female behavior could be mainly due to the absence of the male, the most dominant individual in the group. These female behavioral adjustments are in line with statements from Packer and Pusey (1979) and Dunbar (2013) regarding the lack of female control over males in the baboon genus. The big size of male olive baboons, compared to their female counterpart, seems to provide the male with some degree of influence over female behavior and, consequently, over their sociality. Nevertheless, it should be noted, that despite the possibility that males exercise a certain influence over females, the alpha male of the study seemed to have established a “friendly relationship” with the most dominant female. Strum (1974) defined this type of relationship between males and females as a typical trait of the natural behavior of male baboons. Therefore, the identification of the typical traits of baboons’ natural behavior could be used as an important indicator of animal welfare. In addition, the dominance ranking obtained before male removal and the changes observed in the females’ social behavior after male removal reinforce the idea of a male influence over females.

Unfortunately and, despite the fact that female social interactions varied after male removal, our comparisons are not statistically significative. The small size of the study group, the variability of female dyadic interactions, and the short post-removal period of observation could limit our results and its later interpretations. In this regard, it would have been interesting to increase the information about the sociality of the study group with data regarding the social behavior of young females.  However, the initial procedure designed to study the group sociality in depth, did not contemplate collecting data on the social behavior of young females. Moreover, we assume that dyads respond differently to the demographic changes and that a longer period of post-removal observation could allow us to observe an evolution of the female relationships different from that observed [e.g., the development of stronger and affiliative social relationships observed by Schel et al. (2013) in chimpanzees, one year after modifying the demographic composition of the study group].

This study may be interesting from an applied standpoint, because it shows how the description of the social behavior before and after the removal of an individual from a social group, and their later comparison, can be useful for primate managers to anticipate the behavioral response of animals when facing future modifications of the group sociodemographics. In this sense, some authors (Coe, 1993; Raleigh, McGuire, Brammer, & Yuwiler, 1984; Steklis, Raleigh, Kling, & Tachiki, 1986) have stated that those events that modify the social bonds and the dominance relationships of a group may lead to behavioral and physiological signs of distress for a long time afterward. Our results show how, after male removal, females seem to cope with this social instability by creating a more peaceful scenario. Their sociality does not seem to be negatively affected in the short term by this change. Moreover, our findings confirm that factors such as the social status, the species, and the individual’s characteristics, should be considered when planning the removal of an individual from a social group of primates. We recommend elaborating an accurate plan for the individual’s removal prior to carrying it out. This plan must collect both the knowledge acquired by animal care staff over the years and that obtained through scientific studies such as ours. As a whole, the information here presented ads to the scarce literature surrounding alpha male removal in small groups of primates.