Decreases in Brain Size and Encephalization in Anatomically Modern Humans: Despite evolutionary pressures on the phenotype, intelligence increased since at least 1870 until recently, due to environmental factors

Decreases in Brain Size and Encephalization in Anatomically Modern Humans. Stibel J.M. Brain Behav Evol, Oct 2021. https://doi.org/10.1159/000519504

Abstract: Growth in human brain size and encephalization is well documented throughout much of prehistory and believed to be responsible for increasing cognitive faculties. Over the past 50,000 years, however, both body size and brain mass have decreased but little is known about the scaling relationship between the two. Here, changes to the human brain are examined using matched body remains to determine encephalization levels across an evolutionary timespan. The results find decreases to encephalization levels in modern humans as compared to earlier Holocene H. sapiens and Late Pleistocene anatomically modern Homo. When controlled for lean body mass, encephalization changes are isometric, suggesting that much of the declines in encephalization are driven by recent increases in obesity. A meta-review of genome-wide association studies finds some evidence for selective pressures acting on human cognitive ability, which may be an evolutionary consequence of the more than 5% loss in brain mass over the past 50,000 years.

Keywords: Brain sizeEncephalizationHuman evolutionHuman cognitionGeneral cognitive functionGeneral cognitive ability

Discussion

The current research supports a growing body of evidence demonstrating a decline in human brain size since at least 50 kyr BP [Henneberg, 1988; Henneberg and Steyn, 1993; Ruff et al., 1997]. As compared to the Upper Paleolithic (approx. 50 kyr BP to 15 kyr BP), brain size has declined by 5.415% (p < 0.001, t test) in modern humans. In addition to declines in absolute brain size, Homo encephalization has also declined significantly during modern periods.

Body size changes appear to explain most of the recent changes to brain size. With the exception of the modern sample, encephalization levels remained relatively stable across the past 50,000 years. While the modern sample demonstrated a relatively low level of encephalization, increases in BMI appear to have driven much of the change. There is strong evidence that encephalization in mammals is best understood in terms of lean body mass [Schoenemann, 2004] and the present results suggest that lean body mass may be a better measure at least with respect to comparing within species over time. The modern sample, adjusted for BMI, showed no significant differences in encephalization as compared to AM Homo. After controlling for obesity, modern brain and body mass appear to scale isometrically relative to the prehistoric AM Homo sample. The results herein suggest that recent reductions in brain size are an adaptive response to changing physiology, particularly as it relates to body mass changes.

Nevertheless, there is strong evidence that brain mass is highly correlated with cognitive function evolutionarily [Bouchard Jr. et al., 1990; Posthuma et al., 2002, 2003; Deaner et al., 2007; Pietschnig et al., 2015; Sniekers et al., 2017; Davies et al., 2018; Nave et al., 2018]. Absent structural changes that have made the brain more efficient and significant decreases in brain mass could lead to reductions in cognitive function irrespective of encephalization. To some extent, it is possible that the overall makeup of the brain could have evolved toward greater functionality within a smaller cavity. The skull appears to have evolved from an elongated to a more globular shape roughly at the same time of the slowdown in cranial capacity growth (between 100 and 35 kyr BP), indicative of structural changes to the brain [Neubauer et al., 2018]. However, fossil evidence supports relatively distributed brain size reductions [Henneberg and Steyn, 1993] or inconsistent variations [Balzeau et al., 2012; Liu et al., 2014]. One study reported significantly smaller frontal lobes in modern humans as compared to some but not all early Homo and Neanderthal specimens [Balzeau et al., 2012], despite this brain region being attributed to higher levels of cognition. In contrast, another study found that modern brains appear to have larger frontal lobes as compared to early Homo [Liu et al., 2014].

While more work is needed, the overall results of the various GWAS studies that have examined evolutionary changes to cognitive ability suggest that both general cognitive function and educational attainment are under negative selection pressure. While the genetic correlations and underlying relationships are still not fully understood, the data support a genetic decrease in cognitive ability consistent with an evolutionary decline in brain size.

There is a paradox to the genetic data, however: despite the selective pressures on cognitive ability noted in the GWAS studies, measures of general intelligence and educational attainment have all risen during much of the past century [Flynn, 1984, 1987, 2009; Barro and Lee, 2013; Pietschnig and Voracek, 2015; Conley and Domingue, 2016; Lee and Lee, 2016]. Intelligence, as with most phenotypes, is determined by genetic and environmental causes. Short-term changes in general intelligence are largely driven by environmental factors – such as health, education, and technology – that can offset or enhance long-term genetic trends [Pietschnig and Voracek, 2015; Bratsberg and Rogeberg, 2018]. Genetic intelligence, in contrast, is driven by heredity. In this way, neither brain size nor genetic intelligence is a predeterminate of general intelligence at an individual, group, or species level.

Aggregated data from 14 countries over nearly a century demonstrate the long-term positive impact of environmental factors on human intelligence [Flynn, 1984, 1987, 2009], a phenomenon known as the Flynn effect. Gains in IQ scores across all countries averaged 0.410 points per year, with the majority of countries showing significant increases (Table 3) between 1932 and 2006. Similar results have been found for educational attainment, with average gains of roughly 0.068 years of growth annually between 1870 and 2010 across more than 100 countries [Barro and Lee, 2013; Lee and Lee, 2016] (Table 4).

Table 3.

General intelligence gains (Flynn effect) across multiple cognitive performance tests for 14 nations from 1932 to 2006

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Table 4.

Educational attainment (EA) gains across over 100 nations from 1870 to 2010

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The incongruity between genetic and environmental effects was highlighted in one of the Health and Retirement GWAS studies [Conley and Domingue, 2016], which directly tested whether the effects of negative selection found in polygenic scores of educational attainment manifested themselves in actual decreases in educational attainment. The authors found, consistent with other studies, that educational attainment is increasing in the population despite evolutionary pressures on the phenotype.

Environmental factors are often more transient than genetics so it is not clear whether physical changes to the brain or genetic predispositions will ultimately produce a negative impact on human cognitive ability. There are, however, signs of a possible reversal in the Flynn effect. A significant decrease in IQ has been noted over the past 30 years in many parts of the globe, with the largest declines occurring across industrialized nations [Shayer et al., 2007; Pietschnig and Voracek, 2015; Bratsberg and Rogeberg, 2018; Flynn and Shayer, 2018]. On an evolutionary timescale, environmental improvements may not be able to offset the long-term impact of genetic and physical changes to the brain. This places into question the ability for natural selection in general to drive species level intelligence beyond an upper bound of fitness.

Statements that sounded superficially impressive but lacked intent to communicate meaning generated meaning-seeking, but only when delivered by high admirability speakers (the Dalai Lama) as compared to low admirability speakers (Kim Kardashian)

Kara-Yakoubian, Mane, Ethan A. Meyers, Constantine Sharpinskyi, Anna Dorfman, and Igor Grossmann. 2021. “Hidden Wisdom or Pseudo-profound Bullshit? the Effect of Speaker Admirability.” PsyArXiv. October 28. doi:10.31234/osf.io/tpnkw

Abstract: How do people reason in response to ambiguous messages shared by admirable individuals? Using behavioral markers and self-report questionnaires, in two experiments (N = 571) we examined the influence of speakers’ admirability on meaning-seeking and wise reasoning in response to pseudo-profound bullshit. In both studies, statements that sounded superficially impressive but lacked intent to communicate meaning generated meaning-seeking, but only when delivered by high admirability speakers (e.g., the Dalai Lama) as compared to low admirability speakers (e.g., Kim Kardashian). The effect of speakers’ admirability on meaning-seeking was unique to pseudo-profound bullshit statements and was absent for mundane (Study 1) and motivational (Study 2) statements. In Study 2, participants also engaged in wiser reasoning for pseudo-profound bullshit (vs. motivational) statements and did more so when speakers were high in admirability. These effects occurred independently of the amount of time spent on statements or the complexity of participants’ reflections. It appears that pseudo-profound bullshit can promote epistemic reflection and certain aspects of wisdom, when associated with an admirable speaker.

Check also “Who said it?” How contextual information influences perceived profundity of meaningful quotes and pseudo‐profound bullshit. Vukaڑin Gligoriو  Ana Vilotijeviو. Applied Cognitive Psychology, December 20 2019. https://doi.org/10.1002/acp.3626

Rethinking the Diagnosis of Mental Disorders: Data-Driven Psychological Dimensions, Not Categories, as a Framework for Mental-Health Research, Treatment, and Training

Rethinking the Diagnosis of Mental Disorders: Data-Driven Psychological Dimensions, Not Categories, as a Framework for Mental-Health Research, Treatment, and Training. Christopher C. Conway, Robert F. Krueger, HiTOP Consortium Executive Board. Current Directions in Psychological Science, April 27, 2021. https://doi.org/10.1177/0963721421990353

Abstract: Generations of psychologists have been taught that mental disorder can be carved into discrete categories, each qualitatively different from the others and from normality. This model is now outdated. A preponderance of evidence indicates that (a) individual differences in mental health (health vs. illness) are a matter of degree, not kind, and (b) broad mental-health conditions (e.g., internalizing) account for the tendency of narrower ones (e.g., depression, social anxiety, panic) to co-occur. With these observations in mind, we discuss an alternative diagnostic system, called the Hierarchical Taxonomy of Psychopathology (HiTOP), that describes the broad and specific components of mental disorder. It deconstructs traditional diagnostic categories, such as those listed in the Diagnostic and Statistical Manual of Mental Disorders, and recasts them in terms of profiles of dimensions. Recent findings support the utility of this approach for mental-health research and intervention efforts. HiTOP has the potential to put mental-health research, training, and treatment on a much sounder scientific footing.

Keywords: classification, diagnosis, Hierarchical Taxonomy of Psychopathology (HiTOP), individual differences, mental disorder

Gay men preferred more masculinized faces than did bisexual men; tops preferred feminized faces, whereas bottoms & versatiles preferred masculinized faces; South China gay men preferred more masculinized faces than did those living in North China

Demographic and Geographic Differences in Facial Masculinity Preferences Among Gay and Bisexual Men in China. Lijun Zheng & Jing Zhang. Archives of Sexual Behavior, Oct 25 2021. https://link.springer.com/article/10.1007/s10508-021-02082-w

Abstract: This study examined demographic and geographic differences in facial masculinity preferences among gay and bisexual men in China. The final sample included 2595 participants whose data were obtained from four published data sets and one unpublished data set. Demographic variables included sexual self-label, sexual orientation, age, educational level, and occupational status. Geographic variables were classified based on the IP addresses of respondents including North–South division, administrative division, economic regional division, and modernization division. There were significant differences in facial masculinity preferences in demographic variables. Gay men preferred more masculinized faces than did bisexual men. “Tops” preferred feminized faces, whereas “bottoms” and “versatiles” preferred masculinized faces. Participants aged 20–29 years preferred more masculinized faces than did those aged 16–19 years and older than 30. Also, the results indicated significant differences in facial masculinity preferences in geographic variables. Participants living in South China preferred more masculinized faces than did those living in North China. Concerning administrative division, individuals living in South China (Guangdong, Guangxi, Fujian, and Jiangxi) preferred more masculinized faces than did those living in other regions. Participants living in first-tier cities (Beijing, Shanghai, Guangzhou, and Shenzhen) preferred more masculinized faces than did those living in other cities. The findings implicated context-dependent variability in facial masculinity preferences among gay and bisexual men; facial trait-attribution processes may contribute to these individual differences.

Rolf Degen summarizing... Large-scale, long-term study that allows tracking of individual developments gives the all-clear as regards the dangers of intensive social media use for adolescents

The complex association between social media use intensity and adolescent wellbeing: A longitudinal investigation of five factors that May affect the association. Maartje Boer et al. Computers in Human Behavior, October 28 2021, 107084. https://doi.org/10.1016/j.chb.2021.107084

Highlights

• On average, within-person changes in SMU intensity and wellbeing were not related.

• Within-person relations between SMU and wellbeing varied across adolescents.

• At the between-person level, more SMU was somewhat related to less wellbeing.

• Between-person relations between SMU and wellbeing were confounded by SMU problems.

• Active and passive SMU did not yield differential associations with wellbeing.

Abstract: The present study examined five possible explanations for the mixed findings on the association between adolescents' social media use (SMU) intensity and wellbeing. Particularly, it investigated whether the association between SMU intensity and life satisfaction depended on (1) the type of SMU activity the adolescent engaged in, (2) the (non)linearity of the association, (3) individual differences, (4) inclusion of SMU problems, and (5) the level of analysis. Data from four waves of longitudinal data among 1419 adolescents were used (Mage(T1) = 12.51 (0.60), 45.95% girl). Multilevel analyses showed that at the within-person level, on average, changes in different types of SMU activities were not associated with changes in life satisfaction. Within individuals, the associations ranged from negative to positive across adolescents. In general, this variation could not be explained by adolescents' engagement in upward social comparisons. At the between-person level, the higher adolescents' average intensity of certain SMU activities, the lower their average level of life satisfaction. However, these associations were confounded by adolescents’ SMU problems. No curvilinear associations were found. Overall, the findings underline that to enhance our understanding of the association between SMU and wellbeing in adolescence, it is important to acknowledge the heterogeneity of effects, distinguish between SMU intensity and SMU problems, and disentangle within-from between-person effects.

Keywords: Social media useWellbeingLife satisfactionAdolescentsLongitudinal study

4. Discussion

The present study investigated the extent to which the association between SMU intensity and wellbeing is dependent on (1) the SMU activity adolescents engage in, (2) the (non)linearity of the association, (3) individual differences, (4) whether SMU problems are considered, and (5) the level of analyses. In doing so, we distinguished SMU activities ranging from more active (i.e., SNS posting, IM sending, SNS responding, SNS liking) to more passive (i.e., SNS viewing, IM viewing). Wellbeing was indicated by life satisfaction. At the within-person level, there was no average association between any of the SMU activities and life satisfaction, regardless of whether we controlled for SMU problems. However, the associations at the within-person level varied: For some adolescents, increases in SMU activities were associated with decreases in life satisfaction, whereas for others, increases in SMU activities were associated with increases in life satisfaction. In general, this variation could not be explained by adolescents' tendency to engage in upward social comparisons. At the between-person level, higher average intensity of some more passive activities (i.e., SNS and IM viewing) and one more active (i.e., IM sending) activity were associated with lower average life satisfaction with a small effect size. However, these associations disappeared when controlling for adolescents’ average level of SMU problems. In addition, for none of the SMU activities, evidence was found that the association between SMU intensity and life satisfaction was curvilinear.

Our findings highlight the importance of three factors for understanding the association between SMU activities and wellbeing in adolescence. First, answering the question whether the association between SMU intensity and wellbeing differs across adolescents (RQ3a), our findings showed that within-person effects of SMU intensity ranged from positive to negative across adolescents. This result is in line with experience sampling studies showing that for some adolescents, momentary increases in the intensity of SMU activities were associated with momentary decreases in wellbeing, but for others with increases or no changes in wellbeing (Beyens, Pouwels, Valkenburg, & Van Driel, 2020; Beyens, Pouwels, Van Driel et al., 2020). This study extends these findings as it revealed that also with annual assessments, associations between adolescents’ intensity of SMU activities and life satisfaction varied across adolescents.

Second, answering the question whether a negative association between SMU intensity and wellbeing is driven by SMU problems (RQ4), our findings indicated that negative between-person associations between certain SMU activities and life satisfaction disappeared when controlling for SMU problems. These findings suggest that a negative association between SMU intensity and life satisfaction may be explained by the presence of SMU problems rather than by engagement in specific SMU activities. Therefore, negative associations between SMU intensity and wellbeing revealed in previous studies may have been driven by unobserved SMU problems (e.g., Kelly et al., 2018; Twenge et al., 2018). However, even after controlling for SMU problems, we found that the within-person associations between the SMU activities and life satisfaction ranged from negative to positive. Hence, for some adolescents, increases in SMU activities were associated with decreases in life satisfaction, which could not be attributed to increases in SMU problems.

Third, related to our question at which level a negative association between SMU intensity and wellbeing occurs (RQ5), we found no average associations at the within-person level, while there were negative associations at the between-person level (although only when not controlling for SMU problems). This finding demonstrates that between-level associations do not necessarily reflect within-person dynamics, which was also found in earlier longitudinal studies (Beeres et al., 2020; Coyne et al., 2020; Orben et al., 2019). Conceptually, this finding suggests that the observed between-person association between higher SMU intensity and lower wellbeing was not a causal relation, as changes in SMU intensity were not related to changes in wellbeing within an adolescent.

Above all, some of the factors affecting the association between SMU intensity and life satisfaction need to be considered in concert when understanding this association. As noted above, SMU problems confound the association between certain SMU activities and life satisfaction, but only with regards to between-person associations.

We also examined which type of SMU activity could be detrimental to wellbeing (RQ1). At the within-person level, we found no average associations between any of the SMU activities and life satisfaction, which aligns with findings from experience sampling studies (Beyens, Pouwels, Van Driel et al., 2020; Jensen et al., 2019). At the between-person level, the observed negative associations between adolescents' intensity of engaging in SMU activities and life satisfaction were not specific to passive SMU activities, as proposed by researchers (Liu et al., 2019; Verduyn et al., 2017). In line with our findings, other studies also showed that adolescents’ active as well as passive SMU activities were negatively correlated with their wellbeing at the between-person level (Beyens, Pouwels, Van Driel et al., 2020). Passive and active SMU activities are possibly difficult to disentangle, because adolescents often engage in such SMU activities simultaneously (Valkenburg, Van Driel, & Beyens, 2021). For example, responding to a message on an IM requires viewing that message first. Accordingly, our study showed very high correlations between IM sending and IM viewing at the between-person level. As such, their differential associations with wellbeing may be difficult to grasp, which may explain why in our study IM sending and IM viewing were both negatively related to life satisfaction. However, we stress that these negative associations disappeared when we controlled for SMU problems.

Based on the Goldilocks hypothesis (Przybylski & Weinstein, 2017), we also investigated whether the association between SMU intensity and wellbeing was nonlinear (RQ2), which was not confirmed in our study. Findings of the present study are thereby consistent with other longitudinal studies that did not find curvilinear associations (Houghton et al., 2018; Jensen et al., 2019). Curvilinear associations were mainly found in cross-sectional studies (Przybylski & Weinstein, 2017; Twenge et al., 2018), which could imply that the Goldilocks hypothesis applies to associations at the between-person level at one particular timepoint. Alternatively, earlier found curvilinear associations may have been country-specific. International research shows that the association between adolescents’ SMU and wellbeing are susceptible to country-level factors, for example the extent to which social media are adopted among youth within society (Boer et al., 2020).

Further, we examined whether the association between adolescents’ SMU intensity and wellbeing would depend on the tendency to engage in upward social comparisons (RQ3b). We found no evidence for this moderating effect, with one exception: Among adolescents reporting high levels of upward social comparison, increases in SNS liking were associated with decreases in life satisfaction, which supports the social comparison perspective (De Vries et al., 2018). Among adolescents reporting low levels of upward social comparison, increases in SNS liking were associated with increases in life satisfaction, which corresponds to the emotional contagion perspective (De Vries et al., 2018). However, the individual differences in the associations between SNS liking and life satisfaction were not reduced when upward social comparisons were considered. Also, this was the only moderating effect found out of the six SMU activities that were examined. Therefore, future studies are necessary to replicate our findings.

Our findings provide several implications for future research on the association between SMU intensity and adolescent wellbeing. Specifically, future longitudinal studies that acknowledge heterogeneity in effects, consider SMU problems, and distinguish between within-person and between-person effects would be promising. Research considering these three factors seems more informative than research aiming to disentangle the effects of different SMU activities or examining curvilinear associations. Furthermore, our findings illuminate why earlier studies on the link between SMU intensity and adolescent wellbeing are so inconsistent: Depending on whether researchers investigate specific groups of adolescents, control for SMU problems when examining SMU intensity, or study within-person or between-person associations, the link can range from positive to negative.

In addition, our findings can also inform those concerned with the wellbeing of adolescents, including parents and teachers. They suggest that most adolescents engaging in higher SMU intensity are not at risk for impairments in wellbeing, regardless of whether this concerns engaging in more active or more passive SMU activities. Higher SMU intensity may be considered as normative adolescent behavior that contributes to adolescents’ individual development and daily interaction with peers (Granic, Morita, & Scholten, 2020; Valkenburg & Peter, 2011). Nevertheless, our findings imply that risks to wellbeing could arise when adolescents report SMU problems, indicated by symptoms of addiction (e.g., loss of control over SMU). Therefore, investing in the prevention, early detection, and treatment of problematic SMU may be warranted. Yet, our findings also showed that for a particular group of adolescents, increases in SMU intensity are indicative of decreased wellbeing. Research focusing on identifying the individual characteristics that make adolescents vulnerable to negative SMU effects could provide directions for targeted prevention or intervention programs.

Although we tested many ways in which adolescents’ SMU and their wellbeing could be related, the association may be dependent on more factors that were not addressed in this study. First, it may depend on whom adolescents have contact with on social media. For example, longitudinal research on adults showed that receiving Facebook messages from close friends increased wellbeing, whereas receiving such messages from acquaintances did not change wellbeing (Burke & Kraut, 2016). Other research showed that adolescents who reported more Instagram use with close friends reported more friendship closeness than adolescents who showed less Instagram use with close friends (Pouwels, Valkenburg, Beyens, Van Driel, & Keijsers, 2021). This association was not observed with regards to Instagram use without close friends (Pouwels et al., 2021). Second, the association may depend on the wellbeing outcome being studied. Meta-analytic findings indicate that SMU intensity has different associations with self-esteem and social capital than with life satisfaction (Meier & Reinecke, 2020). Furthermore, research suggests that the association is different for positive indicators of wellbeing than for negative indicators, for example depression and negative affect (Huang, 2017; Wirtz, Tucker, Briggs, & Schoemann, 2020). Third, the association may be contingent on the social media platform used. More specifically, the use of highly visual social media, such as Instagram and Snapchat, may induce more impact than less visual social media, such as Facebook and Twitter. Highly visual social media are mainly focused on uploading visual content, including photos and videos, and allow users to edit this content in more appealing ways using filters (McCrory, Best, & Maddock, 2020). Exposure to modified idealized online portrayals may reinforce a negative body image, which, in turn, could undermine wellbeing (Marengo, Longobardi, Fabris, & Settanni, 2018).

4.1. Strengths and limitations

Using four waves of longitudinal data among secondary school adolescents and a systematic multilevel analytical approach, the present study examined five factors that possibly affect the association between SMU intensity and wellbeing. However, results of this study should be interpreted while considering several limitations. The yearly time intervals of the data used in the present study only allowed for estimating long-term associations. Consequently, potential short-term effects of the intensity of SMU activities could not be captured. Yet, findings from studies on the association between different SMU activities and wellbeing using (multiple) daily assessments showed some comparable results. Often, these studies also observed no average within-person relation between passive and active SMU activities and wellbeing. Also, they showed that these within-person associations ranged from negative to positive across adolescents (Beyens, Pouwels, Valkenburg, & Van Driel, 2020; Beyens, Pouwels, Van Driel et al., 2020; Jensen et al., 2019). Additionally, self-report measures of adolescents’ SMU intensity may not accurately represent actual use, because adolescents may over- or underestimate their use. Indeed, research showed a moderate correlation between self-report and tracked SMU (Parry et al., 2020). Research replicating our study using tracked data of SMU activities is warranted. In addition, the present analyses did not explore the direction of the associations between the intensity of SMU activities and life satisfaction. Studying directionality would require a different analytical approach (e.g., random intercept cross-lagged panel modelling), which cannot be adopted within the present multilevel framework. Although we examined life satisfaction as an outcome of higher SMU intensity, a reverse order may be plausible as well. A meta-analysis on the direction of the association supports our assumption, although it investigated the direction of the relation between screen time in general and depression symptoms (Tang, Werner-Seidler, Torok, Mackinnon, & Christensen, 2021). Finally, the data included considerable dropout of adolescents, which may have affected the quality of the data, especially in the final wave. However, this dropout was mostly not due to individual refusal (i.e., not due to selective dropout), but to classes and schools dropping out. Also, we aimed to limit any potential bias by imputing missing data based on available data at all waves (Madley-Dowd et al., 2019).

Across a variety of economic decision-making situations, we were able to show a more generous attitude towards attractive people; this bias has been shown to be stronger for women, especially when men are the favoring subjects

Voit, M., Weiß, M. & Hewig, J. The benefits of beauty – Individual differences in the pro-attractiveness bias in social decision making. Curr Psychol (2021). Oct 28 2001. https://doi.org/10.1007/s12144-021-02366-3

Abstract: While there already is a huge body of research examining the advantages and disadvantages of physical attractiveness in social and economic decisions, little research has been made to explore the role of individual differences in social decision-making with regard to beauty. To close this scientific gap, we conducted a multiparadigm online study (N = 210; 52% females) in which participants were asked to make decisions in four different economic games facing differently attractive counterparts. Additionally, the personality trait agreeableness was assessed to test for individual differences in decision-making. In exploratory analyses, we also assessed which facet of agreeableness is the most appropriate to predict individual differences in the various economic games. In the study, we were able to replicate the finding of a beauty premium and a plainness penalty but did not find any support for the idea of a beauty penalty. Furthermore, evidence for an opposite-sex advantage was found, which was greater when men were facing women than the other way around. While agreeableness as an overall trait influenced decision making across various paradigms, interactions of distinct facets of agreeableness with the partners’ attractiveness remain heterogeneous and ambiguous. This underlines the importance of integrating the specificity of certain traits in experimental research and the necessity of combining them with different social situations.

Discussion

We investigated how attractiveness and the sex of a social interaction partner affects decision making in four different social and economic paradigms depending on the participants’ sex. To evaluate different aspects of a social interaction, we have chosen the Dictator Game, Trust Game, Ultimatum Game, and Prisoner's Dilemma. Moreover, we examined how the Big Five personality factor agreeableness interacts with decision-making and which particular facet of agreeableness is predictive in the different paradigms.

As expected, participants perceived the attractiveness of their counterparts in line with the intended attractiveness category. Moreover, men rated the range of opposite-sex counterparts’ attractiveness as broader than the range of same-sex partners’ attractiveness. Men thus rated unattractive females as less attractive than unattractive males, whereas attractive females were rated as more attractive than attractive males. Women made no such sex distinctions in the category of attractive and unattractive partners. Hence, men seem to be more judgmental than women towards the partner’s attractiveness when facing a different-sex partner compared to same-sex partners. This is consistent with previous findings (Levy et al., 2008), where men (contrary to women) rated beautiful women as more attractive than beautiful men, which also correlated with enhanced motivational effort for viewing attractive females.

In line with our first hypothesis, we were able to show that in the TG, DG and PD, there was both a clear beauty premium and a plainness penalty, as attractive individuals received more money and higher cooperation rates, whereas unattractive individuals received less money and lower cooperation rates in comparison with moderately attractive individuals. Even in the UG, both a beauty premium and a plainness penalty could be observed for female proposers, when the receiver was male. These findings strengthen the concept of a beauty premium and a plainness penalty, which were firstly described by Hamermesh and Biddle (1993) and further supported by a large body of evidence (e. g., Ma & Hu, 2015; Solnick & Schweitzer, 1999; Wilson & Eckel, 2006). It may be hypothesized that participants show more beneficial economic decisions towards more attractive individuals of both sexes in order to promote positive social relations with them due to their expected qualities (Andreoni & Petrie, 2008; Boyatzis et al., 1998; Dion et al., 1972; Eagly et al., 1991; Feingold, 1992; Langlois et al., 2000; Shinada & Yamagishi, 2014b; Wilson & Eckel, 2006). Accordingly, participants are supposedly less interested in positive interactions and exhibit a lower monetary investment if the social counterpart is of low attractiveness. However, unfair offers from attractive individuals were not rejected more often than unfair offers from less attractive individuals, thus no evidence for a beauty penalty was found. This contradicts our second hypothesis, which was based on the previous findings of Eckel & Wilson (2004) and Andreoni and Petrie (2008) who found attractive individuals who disappointed the participants expectations to be punished harder in a TG and a public goods dilemma, respectively. One has to take into account, though, that in the UG, attractiveness in general seemed to be far less relevant than the size of offer when it comes to decision making. We found no main effect of attractiveness (and only minor advantages for attractive women compared to moderately attractive ones and moderately attractive women compared to unattractive women, when the participant was male) which could explain the absence of a beauty penalty as well. Having identified attractiveness as an important impact factor on social and economic decisions, further research should focus on means to overcome this beauty gap. Moreover, as the beauty gap appears to be greater for women compared to men, unattractive women face a twofold discrimination. Spending so much (well invested) time and energy on discussions of how to overcome the gender gap, society needs to discuss how to deal with this kind of discrimination in everyday and work life. In a recent study placing participants in a hiring position, Tu et al. (2021) found a means to level the gap in an economic context. By asking unattractive individuals to take a powerful body posture, they were rated as being more nonverbally present and the initially found disadvantage in hireability diminished. However, this is not an overarching resolution and may not pay off in social encounters.

Delving into the influence of personality, we could show participants scoring higher on agreeableness as an overall trait tended to be more altruistic, trusting and cooperative. This is consistent with a variety of previous studies who found agreeableness positively linked to cooperation and generosity (e.g., Kagel & McGee, 2014; Koole et al., 2001; Volk et al., 2011; Zhao & Smillie, 2015). Surprisingly and contrary to our third hypothesis, agreeableness did not lead to an increase in decisions in favor of attractive individuals, but even downsized the payment gap between the most and least attractive partners in the DG. As agreeableness was found to play an important role in the inhibition of affect and emotion control (Ode et al., 2008; Robinson, 2007) and the suppression of hostile thoughts (Meier et al., 2006), more agreeable participants may inhibit the urge to favor or discriminate counterparts exclusively based on their (un)attractiveness. However, high levels of agreeableness did not affect the payment and cooperation gap in three out of the four games, but solely led to higher rates of cooperation and payment for all counterparts, regardless of their attractiveness. The abovementioned explanatory approach is thus not completely satisfactory and further research is required. Interestingly, increasing agreeableness scores in women led to decreasing acceptance rates of high and medium offers in the UG. This was not the case for men, who were more likely to accept high offers when scoring high in agreeableness. Further research is needed to determine whether this interaction follows a systematic mechanism or appeared incidentally in our paradigm.

As hypothesized, women benefited more from their attractiveness than men most of the time, contributing to a large body of evidence (Busetta et al., 2013; French, 2002; Kahn et al., 1971; Maestripieri et al., 2017). However, as women were also perceived as more attractive, the origin of this pro-femaleness bias may rather lay in their attractiveness than in their sex. In addition to the pro-femaleness bias, we found evidence for the predicted opposite-sex bias in ratings. The opposite-sex bias was especially large for male participants who preferred attractive female counterparts over attractive male counterparts. This sex difference has already been described in similar studies (e.g., Bhogal et al., 2016) and has also been explained from an evolutionary perspective. While men prefer female mates that show high reproductive value, and thus attractiveness, women emphasize males that present themselves as cooperative and altruistic (see Buss, 1989, for a more detailed discussion). It thus makes sense that males behave in ways that signal resource acquisition, e.g., altruism, generosity, and cooperation when facing highly attractive females. However, in our economic games an opposite-sex bias that depends on attractiveness was only found in DG and PD as evidenced by the three-way interaction of attractiveness, partner sex and participant sex. In these cases, both men and women showed relatively more beneficial economic decisions towards more attractive opposite-sex counterparts. This may be linked to mechanisms of mating behavior in both gender groups and could have an evolutionary background with attractiveness signaling health and fertility for the opposite sex (Maestripieri et al., 2017).

In a recent review, Kou et al. (2020) discuss the underlying cognitive mechanisms influencing the processing of facial attractiveness. They also argue that evolutionary processes may play an important role in both the opposite-sex bias and the femaleness bias when processing differently attractive faces. However, they could not fully discover whether the “female beauty captures attention” or the “opposite-sex beauty captures attention” hypothesis is more likely.

Interestingly, while unattractive women received more money than unattractive men in the DG and in the TG, they faced disadvantages in the PD, where participants cooperated less often with them than with their male counterparts. The reason for these dissimilarities may lay in the differences in the paradigms. Only in the PD, participants rely on their partner’s willingness to cooperate. As they have no other cue than their counterpart’s physical appearance when deciding whether or not to cooperate, the detrimental biases of unattractive counterparts seems to be stronger when facing women than men. In the other paradigms, participants were more generous towards unattractive women than men.

In our explorative analyses we examined which specific facets are especially predictive for decision making in the different paradigms. Concerning the UG and the PD, the facet trust predicted cooperation and acceptance rates to the highest degree. In the TG, increasing scores on the facet of sympathy led to higher amounts of entrusted money. This is counterintuitive as in both the TG and the subscale of trust are supposed to measure trust as a construct and should thus highly correlate. Respectively, in the PD and the UG, one would intuitively expect cooperation to have a stronger influence on decision making than trust. This begs the question whether the subscales of agreeableness do measure distinguishable facets or if the intercorrelation is too high to actually differ between the constructs. It does also underline the importance to include several paradigms and subscales to explore the mechanisms underlying the interaction of attractiveness, the facets of agreeableness and the decision to behave in cooperative, trusting, and altruistic ways.

Taking all the results presented above into account, we found strong support for both a beauty premium and a plainness penalty whereas a beauty penalty could not be observed. Evidence was also found for a stronger pro attractiveness bias for women compared to men, which is in line with a variety of studies. Interestingly, increasing agreeableness did not lead to stronger benefits for attractive counterparts, but rather reduced the beauty gap. Furthermore, in differing economic games, different facets of agreeableness seemed especially predictive. Including multiple games and multiple facets of agreeableness in our study led to a more differentiated and sounder outcome than we would have found with only one specific paradigm.

As a limitation we want to point out the attractiveness differences concerning our counterparts. Both women and men rated moderately attractive females as more attractive than moderately attractive males. This could bias the effects in favor for women and lead to a diminished generalizability. While the reliabilities of the faces were particularly high in the TG and DG (all values of α ≥ 0.85), and acceptable in the UG (most values of α > 0.7), in the PD, however, most reliabilities fell below the critical value of 0.7, as participants differed more severely in their decisions whether or not to cooperate with the different attractive counterparts. Thus, the results for the PD should be taken with caution due to their limited consistency.

To simplify our paradigm, we only included pictures of white, young to middle-aged faces. Future studies should include other races and ages (in both counterparts and participants) to increase the generalizability, as social proximity was found to influence social decisions (Balliet et al., 2014). Moreover, further research is necessary to examine whether the effects are transferable into face-to-face situations.

After a third of houses in a town were covered by lava., people living in them were much more likely to move away permanently; for the children, being induced to move by the “lava shock” dramatically raised lifetime earnings & education

The Gift of Moving: Intergenerational Consequences of a Mobility Shock. Emi Nakamura, Jósef Sigurdsson, Jón Steinsson. The Review of Economic Studies, rdab062, September 20 2021. https://doi.org/10.1093/restud/rdab062

Abstract: We exploit a volcanic “experiment” to study the costs and benefits of geographic mobility. In our experiment, a third of the houses in a town were covered by lava. People living in these houses were much more likely to move away permanently. For the dependents in a household (children), our estimates suggest that being induced to move by the “lava shock” dramatically raised lifetime earnings and education. While large, these estimates come with a substantial amount of statistical uncertainty. The benefits of moving were very unequally distributed across generations: the household heads (parents) were made slightly worse off by the shock. These results suggest large barriers to moving for the children, which imply that labour does not flow to locations where it earns the highest returns. The large gains from moving for the young are surprising in light of the fact that the town affected by our volcanic experiment was (and is) a relatively high income town. We interpret our findings as evidence of the importance of comparative advantage: the gains to moving may be very large for those badly matched to the location they happened to be born in, even if differences in average income are small.

Stability of rejection: Heterosexual men were more likely to report engaging in anti-gay behavior, wanting to avoid contact with gay men; heterosexual women reported a stronger desire to avoid contact with lesbians than did heterosexual men

Gender Differences in Anti-Gay Prejudice: Evidence for Stability and Change. Mary E. Kite, Bernard. E. Whitley, Jr., Kim Buxton & Hannah Ballas. Sex Roles, Oct 28 2021. https://link.springer.com/article/10.1007/s11199-021-01227-4

Abstract: In recent years, there has been remarkable change in societal acceptance of lesbians and gay men. This meta-analysis explored whether this positive shift has reduced the gender difference in these attitudes. We tested Kite and Whitley’s (1996) gender belief system model and replicated their finding that heterosexual men held more negative attitudes toward gay people (g. = 0.37, k = 245, N = 98,295), gay behavior (g. = 0.22, k = 68, N = 98,734), and gay civil rights (g. = 0.16, k = 80, N = 89,187). We also found that heterosexual men were more likely to report engaging in anti-gay behavior (g. = 0.53, k = 7, N = 2,509), endorsing gay stereotypes (g. = 0.17, k = 17, N = 6,936), and wanting to avoid contact with gay men (g. = 0.49, k = 7, N = 2,178). However, heterosexual women reported a stronger desire to avoid contact with lesbians than did heterosexual men (g. = -0.36, k = 5, N = 1,339). For the most part, gender differences remained stable over time; the exceptions were attitudes toward same-gender sexual behavior and attitudes toward lesbian and gay civil rights, which showed small increases. Gender differences in anti-gay prejudice were mediated by gender differences in traditional gender-role beliefs. Moderator variables included participant group, type of measure, and target group.

Romantic dealbreaker factors: Hostile, Unattractive, Unambitious, Filthy, Arrogant, Clingy, and Abusive

Seven deadly sins of potential romantic partners: The dealbreakers of mate choice. Zsófia Csajbók, Mihály Berkics. Personality and Individual Differences, Volume 186, Part B, February 2022, 111334. https://doi.org/10.1016/j.paid.2021.111334

Highlights

• Previous research focused on positive factors of mate preferences.

• Undesirable characteristics of a potential partner may weigh more in mate choice.

• Negative, dealbreaker characteristics loaded on seven factors.

• Dealbreakers complement dealmakers in mate choice.

Abstract: Mate preference research predominantly focused on what people desire in a romantic partner, i.e., dealmakers. It was demonstrated that undesirable traits (dealbreakers) may weigh more in mate choice decisions than desirable traits. We conducted four studies to investigate the key dimensions on which these aversive traits are measured, how the dealbreaker factors complement the dealmaker factors in perceptions of a potential partner, and whether dealbreakers indeed weigh more in mate choice decisions than dealmakers. In Study 1, N = 155 participants reported 96 undesirable characteristics in a potential partner. In Study 2, N = 2445 participants rated these undesirable characteristics according to how much each would make them reject a potential partner. Seven dealbreaker factors were extracted: Hostile, Unattractive, Unambitious, Filthy, Arrogant, Clingy, and Abusive. Study 3 employed the budget-allocation method (N = 1175) and found some consistencies and inconsistencies in the most crucial necessities when measured by dealbreakers vs dealmakers. Lastly, Study 4 found (N = 442) participants were more interested in knowing first their potential partner's dealmaker vs dealbreaker characteristics under constraints. In contrast to previous research, we could not demonstrate the higher importance of relationship dealbreakers when compared to dealmakers, but the two concepts were shown to well complement each other in mate preference research.

Keywords: Mate preferencesMate choiceDealbreakersDealmakersError management theory