Friday, July 16, 2021

Complicated relationship between Machiavellianism and social-cognitive skill: Machiavellianism encompasses features that blend deficiency, proficiency, and average levels of social-cognitive skills

Hart, W., Breeden, C. J., & Kinrade, C. (2021). Re-conceptualizing Machiavellianism and social-cognitive skills: Machiavellianism blends deficient, proficient, and average social-cognitive skills. Journal of Individual Differences, 42(3), 140–147, Jul 2021. https://doi.org/10.1027/1614-0001/a000340

Abstract: Machiavellianism is presumed to encompass advanced social-cognitive skill, but research has generally suggested that Machiavellian individuals are rather deficient in social-cognitive skill. However, previous research on the matter has been limited to measures of (a) Machiavellianism that are unidimensional and saturated with both antagonism and disinhibition and measures (b) only one type of social-cognitive skill. Using a large college sample (N = 461), we examined how various dimensions of Machiavellianism relate to two types of social-cognitive skill: person-perception skill and general social prediction skill. Consistent with some prior theorizing, the planful dimension of Machiavellianism was positively related to both person-perception and general social prediction skills; antagonistic dimensions of Machiavellianism were negatively related to both skills; either agentic or cynical dimensions of Machiavellianism were generally unrelated to both skills. Overall, the current evidence suggests a complicated relationship between Machiavellianism and social-cognitive skill because Machiavellianism encompasses features that blend deficiency, proficiency, and average levels of social-cognitive skills. 



What Makes a Champion? Early Multidisciplinary Practice, Not Early Specialization, Predicts World-Class Performance

What Makes a Champion? Early Multidisciplinary Practice, Not Early Specialization, Predicts World-Class Performance. Arne Güllich, Brooke N. Macnamara, David Z. Hambrick. Perspectives on Psychological Science, July 14, 2021. https://doi.org/10.1177/1745691620974772

Abstract: What explains the acquisition of exceptional human performance? Does a focus on intensive specialized practice facilitate excellence, or is a multidisciplinary practice background better? We investigated this question in sports. Our meta-analysis involved 51 international study reports with 477 effect sizes from 6,096 athletes, including 772 of the world’s top performers. Predictor variables included starting age, age of reaching defined performance milestones, and amounts of coach-led practice and youth-led play (e.g., pickup games) in the athlete’s respective main sport and in other sports. Analyses revealed that (a) adult world-class athletes engaged in more childhood/adolescent multisport practice, started their main sport later, accumulated less main-sport practice, and initially progressed more slowly than did national-class athletes; (b) higher performing youth athletes started playing their main sport earlier, engaged in more main-sport practice but less other-sports practice, and had faster initial progress than did lower performing youth athletes; and (c) youth-led play in any sport had negligible effects on both youth and adult performance. We illustrate parallels from science: Nobel laureates had multidisciplinary study/working experience and slower early progress than did national-level award winners. The findings suggest that variable, multidisciplinary practice experiences are associated with gradual initial discipline-specific progress but greater sustainability of long-term development of excellence.

Keywords: skill acquisition, performance, practice, early specialization, meta-analysis


From 2020... Art, Music, and Literature: Do the Humanities Make Our Lives Richer, Happier, and More Meaningful?

From 2020... Westgate, Erin C. 2020. “Art, Music, and Literature: Do the Humanities Make Our Lives Richer, Happier, and More Meaningful?” PsyArXiv. April 25. doi:10.31234/osf.io/gsnzm

Abstract: For many, there is little more rewarding than the feeling of curling up with a good book, wandering a famous art gallery, or listening to a favorite musician perform live in front of an audience. But do the arts, music, and literature actually make our lives happier, richer, and more meaningful? We suggest they do. In this chapter, we review empirical evidence for the psychological benefits of the humanities, including art, music, and literature, and find that across a wide variety of samples, exposure and engagement is consistently linked to greater well-being. In particular, we suggest that the humanities may increase well-being directly by providing people with enjoyable, rich, and meaningful experiences, as well as indirectly by fostering skills and abilities that contribute to psychological well-being in the long-term. These approaches map onto two mechanisms: 1) direct affective benefits that create enjoyable, rich, and interesting experiences, and 2) indirect cognitive benefits, including social abilities and motivations that promote subjective well-being via interpersonal connection and self- and emotion-regulation. Art, music, and literature may not only provide temporary nourishment for a good life, but teach people lasting skills they can capitalize on to increase long-term well-being.

Check also Lay Beliefs about Meaning in Life: Examinations Across Targets, Time, and Countries. Samantha J. Heintzelman et al. Journal of Research in Personality, August 1 2020, 104003. https://www.bipartisanalliance.com/2020/08/lay-beliefs-about-meaning-in-life.html

Meaning and Evolution: Why Nature Selected Human Minds to Use Meaning. Roy F. Baumeister and William von Hippel. Evolutionary Studies in Imaginative Culture, Vol. 4, No. 1, Symposium on Meaning and Evolution (Spring 2020), pp. 1-18. https://www.bipartisanalliance.com/2020/05/the-scientific-worldview-suggested-that.html

Happiness, Meaning, and Psychological Richness. Shigehiro Oishi, Hyewon Choi, Minkyung Koo, Iolanda Galinha, Keiko Ishii, Asuka Komiya, Maike Luhmann, Christie Scollon, Ji-eun Shin, Hwaryung Lee, Eunkook M. Suh, Joar Vittersّ, Samantha J. Heintzelman, Kostadin Kushlev, Erin C. Westgate, Nicholas Buttrick, Jane Tucker, Charles R. Ebersole, Jordan Axt, Elizabeth Gilbert, Brandon W. Ng, Jaime Kurtz & Lorraine L. Besser . Affective Science volume 1, pages107–115, Jun 23 2020. https://www.bipartisanalliance.com/2020/06/investigating-whether-some-people.html


A large literature characterizes urbanisation as resulting from productivity growth attracting rural workers to cities; these authors think it is in reverse: when rural workers move to cities, the resulting urbanisation yields productivity growth

Urbanisation and the Onset of Modern Economic Growth. Liam Brunt, Cecilia García-Peñalosa. The Economic Journal, ueab050, June 30 2021. https://doi.org/10.1093/ej/ueab050

Abstract: A large literature characterizes urbanisation as resulting from productivity growth attracting rural workers to cities. Incorporating economic geography elements into a growth model, we suggest that causation runs the other way: when rural workers move to cities, the resulting urbanisation produces technological change and productivity growth. Urban density leads to knowledge exchange and innovation, thus creating a positive feedback loop between city size and productivity that initiates sustained economic growth. This model is consistent with the fact that urbanisation rates in Western Europe, most notably England, reached unprecedented levels by the mid-18th century, the eve of the Industrial Revolution.



Mate copying (the increased probability of preferring an individual as a mate, as a result of them having been chosen by same-sex peers previously), does not shows in having a lot of Facebook opposite-sex friends

Non-Independent Mate Choice in Humans: An Investigation of Online Mate Choice Copying and Sex Differences. Cagla Tekin & Ryan C. Anderson. Evolutionary Psychological Science, Jul 15 2021. https://link.springer.com/article/10.1007/s40806-021-00291-z

Abstract: Mate copying (MC) refers to the increased probability of preferring an individual as a mate, as a result of them having been chosen by same-sex peers previously. How changes in the world, such as the increased use of social networking sites, affect MC has not received much attention. Participants were shown photographs of opposite-sex target individuals, and told that the profiles had a high, moderate, or low number of opposite-sex Facebook friends. A two-way analysis of variance (ANOVA) indicated that opposite-sex profiles were considered the most desirable when no information was given about thegender distribution of their Facebook friends. Both men and women found opposite-sex profiles to be least desirable when they had a high number of opposite-sex friends. The findings contribute to the literature by providing further information about the mate selection processes for both sexes, and how social networking sites have changed the way interpersonal relationships are formed. 



Wellcome skepticism... Neither prediction markets (nor surveys) performed well in predicting outcomes for DARPA's Next Generation Social Science programme

Using prediction markets to predict the outcomes in the Defense Advanced Research Projects Agency's next-generation social science programme. Domenico Viganola, Grant Buckles, Yiling Chen, Pablo Diego-Rosell, Magnus Johannesson, Brian A. Nosek, Thomas Pfeiffer, Adam Siegel and Anna Dreber. Royal Society Open Science, July 14 2021. https://doi.org/10.1098/rsos.181308

Abstract: There is evidence that prediction markets are useful tools to aggregate information on researchers' beliefs about scientific results including the outcome of replications. In this study, we use prediction markets to forecast the results of novel experimental designs that test established theories. We set up prediction markets for hypotheses tested in the Defense Advanced Research Projects Agency's (DARPA) Next Generation Social Science (NGS2) programme. Researchers were invited to bet on whether 22 hypotheses would be supported or not. We define support as a test result in the same direction as hypothesized, with a Bayes factor of at least 10 (i.e. a likelihood of the observed data being consistent with the tested hypothesis that is at least 10 times greater compared with the null hypothesis). In addition to betting on this binary outcome, we asked participants to bet on the expected effect size (in Cohen's d) for each hypothesis. Our goal was to recruit at least 50 participants that signed up to participate in these markets. While this was the case, only 39 participants ended up actually trading. Participants also completed a survey on both the binary result and the effect size. We find that neither prediction markets nor surveys performed well in predicting outcomes for NGS2.

4. Discussion

In this project, we find little evidence that researchers can predict outcomes of the hypotheses tested in NGS2. Whether this is due to the relatively small sample of hypotheses (N = 22), participants (N = 39) or the type of hypotheses tested is unclear. Here, unlike in most previous work, participants predicted tests from Bayesian analyses—whether this contributes to the poor performance of the markets and surveys is also unclear. An important difference compared with the previous prediction markets studies on direct replications is also that the original study p-value is an important predictor of replication outcomes, but such information is by definition not available for predicting the NGS2 outcomes, making it a more challenging prediction task for forecasters. Given the previously observed success in experts predicting novel outcomes with forecasting surveys (e.g. [20]), it may be the case that prediction markets function better for replication outcomes relative to forecasting surveys—more work on this topic would be needed for more definitive conclusions.

The current literature on satisfaction in interracial relationships as less satisfied than intraracial relationships may be a reflection of publication bias in which statistically significant differences are published

Differences in Satisfaction? A Meta-Analytic Review of Interracial and Intraracial Relationships. James E. Brooks. Marriage & Family Review, Jul 14 2021. https://doi.org/10.1080/01494929.2021.1937443

Abstract: Empirical investigations on whether there is a difference in relationship satisfaction for partners in interracial compared to intraracial relationships offer contradictory conclusions. The current study reviewed investigations of differences in satisfaction using a meta-analysis to determine whether and under what circumstances there is a difference in relationship satisfaction. Individual, dyadic, environmental, and methodological variations in study participants and designs were explored as potential moderators. Using estimates of effect size d, no overall difference in relationship satisfaction was found between intraracial and interracial relationships. The examination of the moderators revealed that sample size and geographic location of the study impacted whether differences were detected, but most tests for moderation indicated no differences. These conclusions suggest that the current literature on satisfaction in interracial relationships as less satisfied than intraracial relationships may be a reflection of publication bias in which statistically significant differences are published.

Keywords: interracialmarriagemeta-analysisromantic relationshipssatisfaction


Thursday, July 15, 2021

Sociosexuality, comfort with sex outside the confines of a committed relationship, and parent–child dynamics have been associated with experiences of sex guilt

The Experience of Sex Guilt: The Roles of Parenting, Adult Attachment, and Sociosexuality. Jana M. Hackathorn & Esther Malm. Sexuality & Culture, Jul 9 2021. https://link.springer.com/article/10.1007/s12119-021-09887-w

Abstract: Sociosexuality, comfort with sex outside the confines of a committed relationship, and parent–child dynamics have been associated with experiences of sex guilt. However, the mechanisms through which family dynamics are related to sociosexuality and sex guilt are still unclear. Using a developmental framework, in a cross-sectional study, we examined whether attachment styles and parent–child relationships would be associated with the development and maintenance of sociosexuality. We hypothesized that insecure attachment styles and sociosexuality would independently and positively mediate the relationship between parent–child relationship quality (accepting/rejecting) and sex guilt. Findings support past research and suggests that parental rejection predicts insecure attachments, which positively predicts unrestricted sociosexuality, and in turn, is negatively associated with sex guilt. This could suggest that sociosexuality may act as a buffer for sex guilt among this sample.


The cultural success of folk beliefs about the economy is predictable if we consider the influence of specialized, largely automatic inference systems that evolved as adaptations to ancestral human small-scale sociality

Folk-Economic Beliefs: An Evolutionary Cogniti­­ve Model. With Michael Bang Petersen. In Human Cultures through the Scientific Lens: Essays in Evolutionary Cognitive Anthropology. By Pascal Boyer. https://doi.org/10.11647/OBP.0257.09

Abstract: The domain of ‘folk-economics’ consists in explicit beliefs about the economy held by laypeople, untrained in economics, about such topics as, for example, the causes of the wealth of nations, the benefits or drawbacks of markets and international trade, the effects of regulation, the origins of inequality, the connection between work and wages, the economic consequences of immigration, or the possible causes of unemployment. These beliefs are crucial in forming people’s political beliefs and in shaping their reception of different policies. Yet, they often conflict with elementary principles of economic theory and are often described as the consequences of ignorance, irrationality, or specific biases. As we will argue, these past perspectives fail to predict the particular contents of popular folk-economic beliefs and, as a result, there is no systematic study of the cognitive factors involved in their emergence and cultural success. Here we propose that the cultural success of particular beliefs about the economy is predictable if we consider the influence of specialized, largely automatic inference systems that evolved as adaptations to ancestral human small-scale sociality. These systems, for which there is independent evidence, include free-rider detection, fairness-based partner choice, ownership intuitions, coalitional psychology, and more. Information about modern mass-market conditions activates these specific inference systems, resulting in particular intuitions, for example, that impersonal transactions are dangerous or that international trade is a zero-sum game. These intuitions in turn make specific policy proposals more likely than others to become intuitively compelling, and, as a consequence, exert a crucial influence on political choices.


Both organisational & societal conspiracy beliefs are associated with sensation seeking (a preference for exciting and intense experiences); one reason why people believe conspiracy theories is because they find them entertaining

The entertainment value of conspiracy theories. Jan-Willem van Prooijen, Joline Ligthart, Sabine Rosema, Yang Xu. British Journal of Psychology, July 14 2021. https://doi.org/10.1111/bjop.12522

Abstract: Many citizens around the globe believe conspiracy theories. Why are conspiracy theories so appealing? Here, we propose that conspiracy theories elicit intense emotions independent of emotional valence. People therefore find conspiracy theories entertaining – that is, narratives that people perceive as interesting, exciting, and attention-grabbing – and such entertainment appraisals are positively associated with belief in them. Five studies supported these ideas. Participants were exposed to either a conspiratorial or a non-conspiratorial text about the Notre Dame fire (Study 1) or the death of Jeffrey Epstein (preregistered Study 2). The conspiratorial text elicited stronger entertainment appraisals and intense emotions (independent of emotional valence) than the non-conspiratorial text; moreover, entertainment appraisals mediated the effects of the manipulation on conspiracy beliefs. Study 3 indicated that participants endorsed stronger conspiracy beliefs when an election event was described in an entertaining rather than a boring manner. Subsequent findings revealed that both organisational (Study 4) and societal conspiracy beliefs (Study 5) are positively associated with sensation seeking – a trait characterised by a preference for exciting and intense experiences. We conclude that one reason why people believe conspiracy theories is because they find them entertaining.

General discussion

The psychology of belief in conspiracy theories suggests a paradox: Conspiracy beliefs have harmful implications for perceivers and their social environment, yet many people hold such beliefs (Butter & Knight, 2020; Douglas et al., 2017; Jolley & Douglas, 2014a2014b; Van Prooijen, 2018; Van Prooijen & Douglas, 2018). The present research sought to illuminate that conspiracy theories have a psychological payoff for perceivers: People often perceive conspiracy theories as entertaining, which facilitates belief in them. Results of five studies are consistent with this notion. Studies 1 and 2 manipulated exposure to a conspiracy theory (about the Notre Dame fire and Jeffrey Epstein), and results revealed that entertainment appraisals mediated the effects of conspiracy exposure on conspiracy belief. Study 3 manipulated how entertaining or boring a description of an election event was, and this manipulation shaped conspiracy beliefs. Studies 4 and 5 investigated the implications of these insights for the personality trait sensation seeking, which was associated with both belief in organisational conspiracy theories (Study 4) and societal conspiracy theories (Study 5). Together, these studies support the idea that conspiracy theories have entertainment value, which helps explain belief in such theories.

Three more specific theoretical contributions for the emerging research domain of conspiracy beliefs follow from the present research. First, the present studies provide a novel answer to the question why conspiracy theories are so widespread in society. While we do not dispute that, quite often, conspiracy theories emerge from aversive experiences (e.g., societal crisis situations), the present studies expand on a range of recent finding suggesting that conspiracy beliefs sometimes also may have psychological benefits: Belief in conspiracy theories is associated with feeling unique and special (Imhoff & Lamberty, 2017; Lantian et al., 2017), an inflated evaluation of the self (i.e., narcissism; Cichocka et al., 2016) and an inflated evaluation of the groups that are central to a perceiver’s identity (i.e., collective narcissism; Golec de Zavala & Cichocka, 2012; Golec de Zavala & Federico, 2018). But while these previous findings clarify how conspiracy theories may be positively related with people’s self-perception and identity, the present research adds to these findings by revealing that people also may perceive conspiracy theories as entertaining – that is, interesting, exciting, and attention-grabbing narratives.

Second, and relatedly, the present research suggests that not necessarily negative emotions, but rather, intense emotional experiences predict conspiracy beliefs. While the majority of studies have focused on negative feelings and emotions to explain conspiracy beliefs (Grzesiak-Feldman, 2013; Kofta et al., 2020; Newheiser et al., 2011; Van Prooijen, 2016; Van Prooijen & Acker, 2015; Whitson & Galinsky, 2008), research suggests that also various positive emotions can increase conspiracy beliefs (Whitson et al., 2015). Emotional intensity (independent of valence) may reconcile these previous findings, and provides a novel perspective on the role of emotions in conspiracy beliefs. Third, Studies 3 to 5 of the current contribution make the novel point that particularly people scoring high on sensation seeking are susceptible to conspiracy theories. These findings extend previous findings that conspiracy beliefs are associated with the narrower construct susceptibility to boredom (Brotherton & Eser, 2015), and contributes to a body of research suggesting that stable individual difference variables predict people’s susceptibility to conspiracy theories (e.g., Cichocka et al., 2016; Swami et al., 2011). Moreover, Study 3 suggests that particularly people high on sensation seeking associate conspiracy theories with entertainment, underscoring the more general point that the link between situational cues and conspiracy theories are often moderated by other contingencies such as individual difference variables.

The present findings also have broader implications for the role of negative affect in human cognition and behaviour. Feelings of anxiety, uncontrollability, and uncertainty often are interpreted as exclusively aversive experiences that people seek to avoid or regulate (e.g., Park, 2010; Van den Bos, 2009). It has been noted previously, however, that emotional intensity can counter the detrimental effects of negative emotions on overall well-being (e.g., Fujita et al., 1991). As a thought experiment, imagine a study comparing people who have just seen a horror movie (e.g., ‘the Exorcist’) with a neutral control group. We would be quite comfortable to pre-register the prediction that participants who have watched the horror movie provide higher ratings than the control group on variables such as anxiety, uncontrollability, and uncertainty. This does not mean that watching the movie was an aversive experience, however. On the contrary, people deliberately choose to expose themselves to such frightening experiences because they are entertaining. Many experiences in daily life yield emotions that are not only positive or negative but also intense, which have unique implications for human cognition and behaviour (see also Van Boven et al., 2010).

Of importance, the current propositions do not hold normative implications regarding the value of believing in conspiracy theories: Observing that people find conspiracy theories entertaining does not imply a recommendation to endorse them (as an analogy, some people find using drugs or excessive gambling entertaining, yet we do not recommend those activities either). It is well-known that conspiracy theories stimulate harmful behaviours, such as vaccine refusals or decreased efforts to reduce one’s carbon footprints (e.g., Jolley & Douglas, 2014a; Van der Linden, 2015). Rather, the present research was designed to shed light on the scientific question what makes conspiracy theories appealing to people, despite their harmful effects.

Strengths, limitations, and future research

The results across five studies supported a similar conclusion even though we investigated different conspiracy theories in different settings. This is in line with the notion that although conspiracy theories may differ widely in content, belief in such theories is rooted in similar and predictable underlying psychological processes (Douglas et al., 2017; Van Prooijen, 2020; Van Prooijen & Van Vugt, 2018). Furthermore, the studies combined experiments to reveal the effects of conspiracy exposure and entertainment value (Studies 1–3) with cross-sectional studies to investigate the implications of these findings for a role of sensation-seeking in conspiracy theories (Studies 4 and 5). Finally, all the studies reported here were well-powered, and one of the studies was preregistered, suggesting that the current findings are robust and likely to replicate in follow-up studies.

One limitation of the present studies is that in Studies 1–3, emotional valence and emotional intensity were assessed with general measures of only one item. It is possible that more sophisticated measures of specific, discrete emotions with negative valence (e.g., anger, anxiety) shape conspiracy thinking independent of intensity. Also, the scope of the present findings is yet unclear. For instance, the causal evidence for the link between entertainment appraisals and conspiracy beliefs depends on Study 3, but the emotional content of the entertainment condition may have had additional effects unaccounted for (e.g., in acrimonious social settings, actual corruption may be more likely). Furthermore, it is possible that these findings are moderated by stable individual difference variables. Moreover, entertainment is not the only factor predicting conspiracy belief, and quite often genuine distress (e.g., following social crisis situations such as a pandemic or terrorist attack) stimulates conspiracy thinking (Van Prooijen & Douglas, 2017).

Finally, some conspiracy theories may be very entertaining yet not particularly credible (e.g., flat earth conspiracy theories). One might speculate that for the present effects to occur, entertainment appraisals need to include a serious fascination, rooted in the assumption that a conspiracy theory might be true. If one experiences a less serious form of entertainment (e.g., excessive humour after reading a ridiculous conspiracy theory), the effects observed in the present studies are unlikely to occur. At the same time, we should note that anecdotes exist of clearly fictional stories turning into far-fetched conspiracy theories that some people genuinely believe. For instance, the ‘alien lizard’ conspiracy theory (assuming that powerful politicians are a breed of alien lizards disguised as humans) shows strong parallels with the plotline of a science fiction series from the 1980s called ‘V’. Likewise, the novel ‘the Da Vinci Code’ has inspired people to believe the conspiracy theory described in the book (Newheiser et al., 2011). Future research may provide a more fine-grained analysis of the relationships between intense emotional experiences, entertainment appraisals, and conspiracy beliefs.

Compared to heterosexual couples, gay coupless, men and women, tend to have or be willing to accept larger age differences

Age-dissimilar couple relationships: 25 years in review. Lara McKenzie. Journal of Family Theory & Review, July 14 2021. https://doi.org/10.1111/jftr.12427

Abstract: This review explores research over the past quarter century on couples with age differences. I present recent global trends in age-dissimilar couplings, illustrating a shift away from statistical marriage studies focusing on relationships' motivations, inequalities, and challenges, and largely underpinned by biological, economic, or demographic outlooks. Since the last review of age-dissimilar couples in 1993, there have been substantive qualitative developments. Scholarship looking beyond Euro-American contexts is increasingly common, as are approaches examining class, race, sexuality, culture, religion, and nationality, as well as age, marital status, education, and employment. This transformation informs new perspectives on power and partner choice. I argue that research now needs more fluid definitions of age differences, greater range in qualitative studies' geographies and methodologies, and continued consideration of the life course and intersecting differences. Examinations of age-dissimilar couples should thus focus on these relationships' varied configurations, explored through a range of social analyses.


Wednesday, July 14, 2021

The evolution of perennially enlarged breasts in women: Maybe not due to sexual selection, to assist in nursing or other hypotheses; a novel explanation is that they could be a by-product of other evolutionary changes

The evolution of perennially enlarged breasts in women: a critical review and a novel hypothesis. Bogusław Pawłowski, Agnieszka Żelaźniewicz. Biological Reviews, July 13 2021. https://doi.org/10.1111/brv.12778

Abstract: The possession of permanent, adipose breasts in women is a uniquely human trait that develops during puberty, well in advance of the first pregnancy. The adaptive role and developmental pattern of this breast morphology, unusual among primates, remains an unresolved conundrum. The evolutionary origins of this trait have been the focus of many hypotheses, which variously suggest that breasts are a product of sexual selection or of natural selection due to their putative role in assisting in nursing or as a thermoregulatory organ. Alternative hypotheses assume that permanent breasts are a by-product of other evolutionary changes. We review and evaluate these hypotheses in the light of recent literature on breast morphology, physiology, phylogeny, ontogeny, sex differences, and genetics in order to highlight their strengths and flaws and to propose a coherent perspective and a new hypothesis on the evolutionary origins of perennially enlarged breasts in women. We propose that breasts appeared as early as Homo ergaster, originally as a by-product of other coincident evolutionary processes of adaptive significance. These included an increase in subcutaneous fat tissue (SFT) in response to the demands of thermoregulatory and energy storage, and of the ontogenetic development of the evolving brain. An increase in SFT triggered an increase in oestradiol levels (E2). An increase in meat in the diet of early Homo allowed for further hormonal changes, such as greater dehydroepiandrosterone (DHEA/S) synthesis, which were crucial for brain evolution. DHEA/S is also easily converted to E2 in E2-sensitive body parts, such as breasts and gluteofemoral regions, causing fat accumulation in these regions, enabling the evolution of perennially enlarged breasts. Furthermore, it is also plausible that after enlarged breasts appeared, they were co-opted for other functions, such as attracting mates and indicating biological condition. Finally, we argue that the multifold adaptive benefits of SFT increase and hormonal changes outweighed the possible costs of perennially enlarged breasts, enabling their further development.


Masculine Voices Predict Attachment Style and Relationship Communication Patterns in Romantic Relationships

Masculine Voices Predict Attachment Style and Relationship Communication Patterns in Romantic Relationships. Jing Zhang &Lijun Zheng. Journal of Sex & Marital Therapy, Volume 47, 2021 - Issue 3, Pages 262-269, Jan 6 2021. https://doi.org/10.1080/0092623X.2020.1869125

Abstract: Humans exhibit sexually-based vocal dimorphisms, providing information about peoples’ intrinsic states. Studies indicate that voice pitch predicts relationship quality; however, none have explored its effects on relationship maintenance. We explored the association between sexually dimorphic vocal properties [voice pitch, measured by fundamental frequency (F0) and F0 variation, the within-subject SD in F0 across the utterance (F0-SD)], attachment styles, and communication patterns among Chinese heterosexuals in romantic relationships. Men’s F0-SD positively correlates with constructive communication pattern and negatively correlates with avoidant attachment style. No significant correlations are found for women. These findings suggest that men with masculine voices are more avoidantly attached, using avoidant communications. Furthermore, they show that voice may play a crucial role in and be an important morphological index of human mating relationships.

Keywords: Voicerelationshipattachment stylecommunicationmasculinity

Check also Do men with more masculine voices have better immunocompetence? Steven Arnocky et al. Evolution and Human Behavior, Jun 2018. https://www.bipartisanalliance.com/2018/06/do-men-with-more-masculine-voices-have.html


Observed gender differences in prescriptive gender stereotypes were smaller or non-existent for sexual and ethnic minority targets compared to straight and White targets

Hudson, Sa-kiera T. J., and Asma Ghani. 2021. “Sexual Orientation and Race Mute the Prescriptive Nature of Gender Stereotypes.” PsyArXiv. July 1. doi:10.31234/osf.io/9uxwz

Abstract: There is substantial research on the nature and impact of gender prescriptive stereotypes. However, there has been relatively little work on whether these stereotypes are equally applicable to men and women of different identities. Across two studies (total N = 1074), we assessed gender prescriptive stereotypes intersectionality in an American context, for men and women of different sexual orientations (Study 1) and races (Study 2). Results show strong evidence of a straight-centric bias, as prescriptive stereotypes of men and women most closely aligned with those of straight men and women, but limited evidence for a White-centric bias. Furthermore, observed gender differences in prescriptive stereotypes were smaller or non-existent for sexual and ethnic minority targets compared to straight and White targets, suggesting that theories around the dyadic nature of gender stereotypes between men and women might be restricted to straight and White men and women.



Clone images elicited higher eeriness than individuals with different faces; related to distinguishableness of each face, the duplication of identity, avoidance reactions based on disgust sensitivity, inter alia

Yonemitsu F, Sasaki K, Gobara A, Yamada Y (2021) The clone devaluation effect: A new uncanny phenomenon concerning facial identity. PLoS ONE 16(7): e0254396. Jul 13 2021. https://doi.org/10.1371/journal.pone.0254396

Abstract: Technological advances in robotics have already produced robots that are indistinguishable from human beings. This technology is overcoming the uncanny valley, which refers to the unpleasant feelings that arise from humanoid robots that are similar in appearance to real humans to some extent. If humanoid robots with the same appearance are mass-produced and become commonplace, we may encounter circumstances in which people or human-like products have faces with the exact same appearance in the future. This leads to the following question: what impressions do clones elicit? To respond to this question, we examined what impressions images of people with the same face (clone images) induce. In the six studies we conducted, we consistently reported that clone images elicited higher eeriness than individuals with different faces; we named this new phenomenon the clone devaluation effect. We found that the clone devaluation effect reflected the perceived improbability of facial duplication. Moreover, this phenomenon was related to distinguishableness of each face, the duplication of identity, the background scene in observing clone faces, and avoidance reactions based on disgust sensitivity. These findings suggest that the clone devaluation effect is a product of multiple processes related to memory, emotion, and face recognition systems.

General discussion

Our six studies investigated the impressions formed by clone faces and factors to influence the impression of clone faces. The participants evaluated six individuals with clone faces as eerier and more improbable than those with different faces and a person with a single face (Study 1). We called this negatively emotional response to clone faces the clone devaluation effect. This effect was stronger as the number of clone faces increased from two to four persons (Study 2). Moreover, this effect did not occur when each clone face was indistinguishable like animal faces (Study 3). It was also shown that the duplication of identity rather than facial features has an important role in this effect and clone faces with the duplication of identity were eerier (Studies 4a & 4b). The clone devaluation effect became weaker when clone faces existed in the lower reality of the context (Study 5). Furthermore, the eeriness of clone faces stemming from improbability would be positively predicted by disgust, in particular animal-reminder disgust (Study 6). Taken together, these results suggest that clone faces induce eeriness and that the clone devaluation effect is related to the realism and disgust reaction. We discuss the details of an assumed mechanism below.

Our findings provide evidence for the internal mechanisms of the clone devaluation effect. The results of Study 6 imply a relationship among realism, the eeriness of clone faces, and animal-reminder disgust sensitivity. The domain of animal-reminder disgust sensitivity includes the lack of the ideal appearance in a human body such as death or a damaged exterior form [30]. In addition to this idea, a previous study indicated that animal-reminder disgust is also involved in the eeriness of humanlike objects such as androids [31], the appearance of which is often improbable and strange. Objects with clone faces, even though they have an absolute appearance in human bodies, might be judged as strange because the clone faces are improbable. As a result, the eeriness is elicited in order to avoid any harm from such improbable and strange objects (i.e., clone faces). Taken together, the improbability of the clone faces is assumed to trigger a defensive reaction stemming from animal-reminder disgust, which in turn plays key roles in emotional reactions (i.e., eeriness).

Considering that improbability and strangeness are the keys to the phenomenon of the clone devaluation effect, a lack of humanity is another of the important parts of the effect. What is involved in the lack of humanity? The results of Studies 4a and 4b indicate that it is likely that this lack of humanity stems from duplication of identity, not facial features. Faces are important information for identifying individuals because human beings have a one-to-one correspondence between face and identity in principle. However, clone faces violate this principle, which may make us misjudge that the identity of people with clone faces should be the same. Thus, the duplication of identity is contrary to the principle of human beings and thus could be considered as a lack of humanity. In most of the present studies except for 4a and 4b, the clone devaluation occurred without the manipulation of identity; observers deduced duplication of identity from clone faces and, as a result, eeriness was elicited. However, we showed that the eeriness of the clone faces was low when clone faces were judged as multiplets; they have the same facial features. In this case, the participants were able to assign clone faces to different identities and thus eeriness was not evoked. Considering this, faces are the most critical cue of personal identity when there is no other special cue (e.g., details of siblings). This idea is consistent with the findings of previous studies [3233]. Taken together, the lack of humanity in the clone devaluation effect may stem from the duplication of identities inferred by clone faces.

Considering the findings of our six studies, it was possible to some extent to speculate on a mechanism of the clone devaluation effect (Fig 9). Initially, when one observes clone faces, they are analyzed based on facial features. In this case, because they have identical facial features, they are judged as the same faces. This point is supported by Study 3, which showed that the clone devaluation effect did not occur when clone faces could not be analyzed and distinguished. Several models of aesthetic and facial processing argued that visual features were analyzed and abstracted from objects in the first stage [3436]. Therefore, it is appropriate to assume that facial features are analyzed as the first stage of the facial processing system. After the judgment of clone faces, their information is processed in the memory system. In this stage, the realism of encountered clone faces is evaluated based on prior knowledge and experience. The results of studies 4a and 4b reflected this processing because the eeriness of famous or little-known multiplets’ faces was diminished even if they have clone faces. This stage is related to the reality of the background scene in which the clone faces exist, which supported the results of study 5’s that the eeriness and improbability of the photographic clone faces was higher than the cartoon clone faces. Although the present study only used the cartoon scene as less realistic scene than the photographic scene, we can investigate the influence of the background scene in further detail if the virtual reality space in which 3D avatars with clone faces existed was used as a more realistic scene. Finally, the improbability of clone faces induces avoidance reaction to strangers, which stems from disgust. Through this processing, unpleasant emotions (i.e., eeriness) toward clone faces are finally evoked.


Fig 9. The mechanism of the clone devaluation effect proposed in the present study.

The emergence of objects with clone faces is not a mere fantasy; they can be expected to appear in the near future. For example, when humanoid technology has further developed, the appearance of humanoids will be the same as that of humans, and the mass production of such humanoids will be possible. Further, the uncanny valley may disappear in humanoids. The present study indicates that clone faces elicit eeriness. This suggests an irony: even if this new technology can bridge the uncanny valley, a new eerie phenomenon (i.e., the clone devaluation effect) would appear alongside new technologies like human cloning techniques or robotic development. The results of a previous study that investigated public attitudes towards human cloning in the United Kingdom found that people have relatively negative responses to reproductive cloning technology [37]. However, unlike this survey, the present study created an experimental situation in which new technologies such as cloning human were realized and found that people tended to evaluate clone faces negatively. Therefore, our findings shed light on the negative aspects of the development of new technology and we urge the reconsideration of the rapid introduction of such technologies into society from the perspective of psychological responses instead of bioethics.

The present study has some limitations, which suggest the need for further research on the clone devaluation effect. First, we used dog faces in Study 3 to investigate the influence of distinguishableness of faces on the clone devaluation effect. However, there is another effect that enables human beings to easily distinguish faces that belong to their own racial group, which is known as the other-race effect [e.g., 38]. To explore the influence of distinguishableness in detail, this effect may be helpful. If other-race faces are used as clone faces, the clone devaluation effect would be weaker than own-race faces or not occur. Second, we should also set up an experimental scene to simulate real-life situations in the near future. In most of our studies, we presented clone faces of humans mainly because we assumed a future where technology overcomes the uncanny valley. However, it is possible that robots with features less similar to human faces, which have not fallen into the uncanny valley, will become popular before more human-like robots will be available on the market. As the results of Study 3 imply, the clone devaluation effect is unlikely to occur in non-human clone faces. Considering this, we speculated that if robots with features less similar to human faces are clearly perceived as robots, not humans, the clone devaluation effect would not occur in clone faces of such robots. Third, it is possible that the observation time of the clone faces varied depending on the participants, which may have affected the results of the present study since we did not control the exposure time of clone faces. Observing clone faces for a long time may lead to habituation, resulting in reduced clone devaluation effects. Therefore, to reveal a temporal aspect of the clone devaluation effect (e.g., minimum time for the clone devaluation effect to occur) future studies should manipulate the exposure time of clone faces.

In conclusion, the present study has identified the clone devaluation effect, which asserts that clone faces elicit eeriness. The improbability and lack of humanity of the clone faces were related to this effect. Moreover, the duplication of identity, not facial features, had key roles in the clone devaluation effect. Furthermore, the clone devaluation effect stemmed from disgust and avoidance reactions (particularly, animal-reminder disgust). The present study suggests it is possible that the introduction of new technology in robotics or the cloning of human beings into society may cause unpleasant psychological reactions in the future.


Life satisfaction does not adapt to high income: After five or more years, people who maintain high incomes still have higher life satisfaction than the average population

Happiness adaptation to high income: Evidence from German panel data. Jianbo Luo. Economics Letters, July 13 2021, 109995. https://doi.org/10.1016/j.econlet.2021.109995

Highlights

• Life satisfaction does not adapt to high income.

• After five or more years, people who maintain high incomes still have higher life satisfaction.

Abstract: This paper is the first to use national representative panel data to demonstrate that individuals do not adapt to high income in the long run: after five or more years, the life satisfaction of high-income people is still higher than that of the average population. Using entropy balancing (EB) matching and Lasso variable selection to reweight the control group yields similar results.

Keywords: High incomeSubjective well-beingAdaptationEntropy balancingMachine learning Lasso




Wearing an opposite-sex virtual body enhanced participants’ perceptions of pleasantness and erogeneity for caresses on intimate areas from a same-sex toucher; this effect was stronger in men than in women

Wearing same- and opposite-sex virtual bodies and seeing them caressed in intimate areas. Manuel Mello et al. Quarterly Journal of Experimental Psychology, July 9, 2021. https://doi.org/10.1177/17470218211031557

Abstract: Immersive virtual reality enables people to undergo the experience of owning an artificial body and vicariously feeling tactile stimuli delivered to it. However, it is currently unknown how such experiences are modified by the sexual congruency between the human and the artificial agent. In two studies, heterosexual men (Experiment 1) and women (Experiment 2) embodied same-sex and opposite-sex avatars and were asked to evaluate the experience (e.g., pleasantness, erogeneity) of being touched on social or intimate areas of their virtual body by a male or female avatar. Electrocardiogram and galvanic skin response were also recorded. Moreover, participants’ implicit and explicit gender biases were examined via a gender-potency implicit association test and the Ambivalent Sexism Inventory. When embodying a same-sex avatar, men and women rated caresses on intimate areas from an avatar of the opposite sex as more pleasant and erogenous. Conversely, body swap—that is, wearing an opposite-sex avatar—enhanced participants’ perceptions of pleasantness and erogeneity for caresses on intimate areas from a same-sex toucher. This effect was stronger in men than in women. Furthermore, physiological correlates of enhanced processing of arousing stimuli predicted behavioural outcomes during the body swap illusion. Wearing an opposite-sex avatar affects one’s own body representations and may have important implications on people’s attitudes and implicit reactivity to touch-mediated interactions. Men seem more susceptible to this type of body swap illusion. Our paradigm may induce profound changes of cross-sex perspective-taking and provide novel tools for promoting empathy and comprehension of sex-related diversity.

Keywords: Body ownership, social touch, virtual reality, embodiment, body swap, sex differences


Yawning Is More Contagious in Pregnant Than Nulliparous Women

Yawning Is More Contagious in Pregnant Than Nulliparous Women. Naturalistic and Experimental Evidence. Ivan Norscia, Lucia Agostini, Alessia Moroni, Marta Caselli, Margherita Micheletti-Cremasco, Concetta Vardé & Elisabetta Palagi. Human Nature, Jul 13 2021. https://rd.springer.com/article/10.1007/s12110-021-09404-w

Abstract: Contrary to spontaneous yawning, which is widespread in vertebrates and probably evolutionary ancient, contagious yawning—yawning triggered by others’ yawns—is considered an evolutionarily recent phenomenon, found in species characterized by complex sociality. Whether the social asymmetry observed in the occurrence of contagious yawning is related to social and emotional attachment and may therefore reflect emotional contagion is a subject of debate. In this study we assessed whether yawn contagion was enhanced in pregnant women, a cohort of subjects who develop prenatal emotional attachment in preparation for parental care, via hormonal and neurobiological changes. We predicted that if yawn contagion underlies social and emotional attachment, pregnant women would be more likely to contagiously yawn than nonpregnant, nulliparous women of reproductive age. We gathered data in two different settings. In the experimental setting, 49 women were exposed to video stimuli of newborns either yawning or moving their mouth (control) and we video-recorded the women during repeated trials to measure their yawning response. In the naturalistic setting, 131 women were observed in a social environment and their yawning response was recorded. We tested the factors influencing the yawning response, including the reproductive status (pregnant vs. not pregnant). In both settings, yawn contagion occurred significantly more in pregnant than nonpregnant women. By showing that pregnant women were most likely to respond to others’ yawns, our results support the hypothesis that the social variation observed in yawn contagion may be influenced by emotional attachment and that yawning in highly social species might have been coopted for emotional contagion during evolution.


Discussion

The results from both the experimental and the naturalistic data converge in indicating that women’s reproductive status had an effect on contagious yawning, which was more likely to occur in pregnant than in nulliparous women (here defined as women who were not pregnant and had no children). As a matter of fact, pregnant women were more likely to respond than nulliparous women to both video yawns of unknown infants in the experimental trials and live yawns from adults in the naturalistic setting (Tables 2 and 3; Figs. 3 and 5). This finding, presented for the first time with this study, provides support to the Emotional Bias Hypothesis (EBH) because yawn contagion was highest in the category of women characterized by enhanced social attachment predisposition, owing to the biological and psychological changes typical of the gestation period (Barba-Müller et al. 2019; Brandon et al. 2009; Tichelman et al. 2019).

Since yawn contagion has been found to vary across the day (Giganti and Zilli 2011), we checked whether our yawning response sampling could be biased by the time periods during which the data were collected, depending on the availability of the study subjects. In neither setting did we find a significant effect (Tables 1 and 3), probably because the majority of the data was collected in the morning and in the afternoon (with little data collected at the very extremes of the day).

The use of a twofold approach, involving both experimental and naturalistic data collection, allowed the verification of the possible effect of different variables on yawn contagion. The results of the experimental trials show that the yawning response was significantly higher in the yawning than in the control video condition (Table 1; Fig. 2). This finding confirms that yawn contagion was present in the cohort of human subjects considered in this study (nulliparous and pregnant women) since it has been found in other segments of the population (Arnott et al. 2009; Provine 19892005).

Yawn contagion may be affected by selective, top-down attentional biases (Massen and Gallup 2017), in addition to bottom-up, stimulus-driven attention (Attentional Bias Hypothesis, ABH; Palagi et al. 2020). Therefore, in the experimental setting we checked for selective attention to the stimulus and we found no significant influence of the time of attention to the stimulus source (video screen) on yawning (Table 1), which was high overall in both yawning and control video conditions, as well as in pregnant and nulliparous women. This finding reduces the probability that in our sample a selective attention bias may have accounted for the differences between stimulus (yawning/control) and reproductive status (pregnant/nulliparous) conditions. This is line with evidence indicating, directly or indirectly, that contagious yawning in humans may depend on bottom-up more than top-down selective attention (Norscia et al. 2020; for a review see Palagi et al. 2020). Age is another variable known to possibly affect yawn contagion rates (Bartholomew and Cirulli 2014). In our case, in the experimental setting there was a nonsignificant trend of the influence of age in the yawning response, possibly because the women under study fell within the relatively short reproductive age.

In the naturalistic setting we could verify the effect of a social bond between the trigger and the potential responder on the yawning response. Although the bond was restricted to two categories (strangers and acquaintances) owing to data constraints, and despite showing an inverse correlation with reproductive status, the bond had a significant effect on yawn contagion, which was more likely between subjects who knew each other than between strangers. This finding is in agreement with previous literature showing that relationship quality has an influence on yawn contagion, whose likelihood increases as the strength of the social bond increases (from strangers to acquaintances, friends, and lastly to family members; Norscia and Palagi 2011; Norscia et al. 2016). Norscia et al., (2020) found no difference between strangers and acquaintances when the yawns were heard but not seen, although friends and family responded at significantly higher rates than did those in the other categories. In the absence of the visual cue, it is probably more difficult for the potential responders to discern between subjects with whom they have reduced or no familiarity.

Importantly, our results from the experimental trials show that reproductive status (pregnant/nulliparous) had a significant effect on the yawning response in the yawning video condition but not in the control video condition (cf. Tables 2 and 3). Therefore, only yawning resulting from contagion—and not spontaneous yawning—was affected by pregnancy in our sample. Historical accounts report an increase of spontaneous yawning in the case of certain diseases (e.g., puerperal fever or hemorrhage; Walusinski 2010), and excessive yawning has indeed been indicated as a possible marker of disease in humans (Thompson and Simonsen 2015). Progesterone increases daytime drowsiness and sleeping time (Won 2015) and so it may increase spontaneous yawning rate during pregnancy. In this respect, we cannot exclude that the yawning stimulus might have preferentially primed the yawning motor response in pregnant women also because they experienced increased fatigue (despite showing similar levels of sleep to those of nulliparous women). An investigation on how spontaneous rates vary within subjects across pregnancy, possibly in relation to fatigue and tiredness, and how contagious yawning varies depending on the stimulus (e.g., babies/adults)—with hormonal and neurobiological correlates—could better clarify the above issues.

Overall, the different yawning response of pregnant women relative to women with no children can fall within the broad range of the behavioral changes that start occurring during pregnancy, such as motor activity and dietary choice variations (Crozier et al. 2009; Gradmark et al. 2011). Compared with childless women, pregnant women show increased sensitivity to emotional signals and facial expressions. For example, pregnant women were found to perceive infant cries in more differentiated ways than women with no offspring (Bleichfeld and Moely 1984; Yoshiaki 1985). As gestation progresses, pregnant women also show enhanced ability to encode and process emotional faces, especially related to distress (an emotional state; Keltner et al. 2019) as an evolutionary adaptation to motherhood, which requires hypersensitivity to emotional threat signals and contagion (Osório et al. 2018; Pearson et al. 2009). Our results fit with this scenario because they indicate enhanced responsiveness of pregnant women to yawning, which has been linked (with various degrees of evidence) to anxiety and distress in human and nonhuman primates (from lemurs to apes: e.g., Baker and Aureli 1997; Coleman and Pierre 2014; Leone et al. 2014; Palagi et al. 2019; Thompson 20142017; Thompson and Bishop 2012; Zannella et al. 2015). Thompson (2014) has posited that cortisol (involved in the stress response) may be involved in yawn contagion, at least under certain situations. Another hypothesis, not mutually exclusive to the cortisol hypothesis, may be that yawn contagion is, to a certain extent, under the influence of oxytocin, considering that enhanced emotional recognition is one of the effects of oxytocin, whose levels largely increase during pregnancy (Domes et al. 2007; Preston 2013). In particular, oxytocin appears to increase the accuracy of the recognition of faces displaying angry and happy emotions, especially in women (Yue et al. 2018). Mariscal et al., (2019) found that yawn contagion in autism spectrum disorder (ASD) children was positively related to the blood concentration of oxytocin. The possible relationship between oxytocin and yawn contagion is supported by evidence that yawn contagion in humans follows the empathic gradient (sensu Preston and de Waal 2002), being highest between closely bonded subjects (Norscia and Palagi 2011; Norscia et al. 2020). Some features typical of mother-infant attachment, such as social recognition, bonding, and affiliation, are maintained in adulthood and promoted by oxytocin, which has been found to increase trust (Kosfeld et al. 2005), generosity (Zak et al. 2007), altruism (de Dreu et al. 2010), and both cognitive and affective empathy (Rodrigues et al. 2009; Shamay-Tsoory et al. 2013; Smith et al. 2014; Uzefovsky et al. 2015). One of the future steps is to evaluate the possible covariation between oxytocin and yawn contagion in both pregnant and nulliparous women. Beyond incorporating hormones, further studies could involve postmenopausal versus pregnant women and check how mothers react when they see their own fetus yawning on the echograph screen.

The possible connection between yawn contagion and increased social and emotional bonding is also suggested by the fact that some of the areas that seem to be involved in yawn contagion (such as the ventromedial-prefrontal cortex, superior temporal sulcus, amygdala, insula, posterior cingulate, and precuneus; Nahab et al. 2009; Platek et al. 2005; Schürmann et al. 2005) are also involved in mother-infant care, in mother’s enhanced sensitivity to the baby, and maternal brain changes occurring during pregnancy (Barba-Müller et al. 2019; Hoekzema et al. 2017; Kikuchi and Noriuchi 2015; Preston 2013; Rifkin-Graboi et al. 2015).

In summary, by showing increased occurrence of yawn contagion in pregnant women—a cohort of subjects that is specifically “programmed” to recognize and respond to others’ emotions—this study provides support for the hypothesis that yawn contagion may, at least under certain circumstances, underlie emotional contagion (EBH; Palagi et al. 2020). This process is considered by some scholars a basic form of empathy and occurs when an emotion is transferred from one individual to another, possibly via a motor perception–action mechanism, involving the matching of facial expressions and the resonance of the emotions that underlie such expressions (de Waal and Preston 2017).

The perception–action and the offspring care model both predict that subjects can preferentially attend the stimuli coming from closely bonded others, particularly caregiving individuals such as pregnant women toward babies (Preston 2013; Preston and de Waal 2002). Visual, top-down attention has limited effect on yawn contagion and does not follow a consistent familiarity trend in hominines because other factors, such as dominance, can come into play (Lewis et al. 2021; Norscia et al. 2020; Palagi et al. 2020). Hence, a possible bonding hypothesis between EBH and ABH is that yawn contagion can be influenced by emotional bonding and attention, mainly directed through bottom-up mechanisms.

Importantly, not all contagious yawning is triggered by emotional resonance, and that is not the point in question here. Contagious yawning also occurs between strangers (Norscia and Palagi 2011), and some people are consistently not susceptible to others’ yawns (Bartholomew and Cirulli 2014; Platek et al. 2003; Provine 19861989). Contagious yawning is a form of yawning and—as such—can be related to nonemotional, individual and/or environmental factors, such as time of the day (Giganti and Zilli 2011), age (Bartholomew and Cirulli 2014), and possibly temperature (Gallup and Eldakar 2011). The perception–action mechanism itself is based on a theory in motor control that assumes that our physical motor acts are primed in the brain by observation of those in others, even if they do not bear emotional cues (Preston and de Waal 2002). Thus, contagious yawning can also be a nonemotional motoric response. The pivot around which this study revolves is the possible mechanism leading to the social variations observed in the occurrence of contagious yawning. Although still under debate (Adriaense et al. 2020; Massen and Gallup 2017), various physiological, neuroethological, and psychological studies sustain the possible connection between the social asymmetry of yawn contagion and emotional bonding. Some of the brain areas that appear to be involved in yawn contagion (Nahab et al. 2009; Platek et al. 2005; Schürmann et al. 2005) seem to overlap with those involved in emotional processing of internal and external stimuli and empathy (Palagi et al. 2020) and—importantly—with the maternal brain (Barba-Müller et al. 2019; Hoekzema et al. 2017; Kikuchi and Noriuchi 2015; Rifkin-Graboi et al. 2015). Highest levels of yawn contagion are associated with increased oxytocin levels (i.e., ASD children; Mariscal et al. 2019), enhanced social bonding (i.e., between friends and family; Norscia and Palagi 2011), and maternal prenatal bonding (i.e., in pregnant women; present study). Lower yawn contagion rates in association with levels of autistic traits were found to be related to attentive rather than background emotional empathy deficits (Helt et al. 2021). Finally, another study found that subjects who yawned in response to observing others’ yawns exhibited significantly higher empathy scores (Franzen et al. 2018).

Hence, although we cannot discard the possibility that other priming and motor mechanisms may also underlie the social asymmetry of yawn contagion, the hypothesis that this behavior has been coopted during evolution for emotional contagion still stands and gains further support.