Specific cognitive abilities (SCA) are 56% heritable, similar to general intelligence, g; some SCA are significantly more or less heritable than others, 39-64%; SCA do not show the dramatic developmental increase in heritability seen for g

The genetics of specific cognitive abilities. Francesca Procopioa et al. Intelligence, Volume 95, November–December 2022, 101689. https://doi.org/10.1016/j.intell.2022.101689

Highlights

• Specific cognitive abilities (SCA) are 56% heritable, similar to g.

• Some SCA are significantly more heritable than others, 39% to 64%.

• Independent of g (‘SCA.g’), SCA remain substantially heritable (∼50%).

• SCA do not show the dramatic developmental increase in heritability seen for g.

• Genomic research on SCA.g is needed to create profiles of strengths and weaknesses.

Abstract: Most research on individual differences in performance on tests of cognitive ability focuses on general cognitive ability (g), the highest level in the three-level Cattell-Horn-Carroll (CHC) hierarchical model of intelligence. About 50% of the variance of g is due to inherited DNA differences (heritability) which increases across development. Much less is known about the genetics of the middle level of the CHC model, which includes 16 broad factors such as fluid reasoning, processing speed, and quantitative knowledge. We provide a meta-analytic review of 747,567 monozygotic-dizygotic twin comparisons from 77 publications for these middle-level factors, which we refer to as specific cognitive abilities (SCA), even though these factors are not independent of g. Twin comparisons were available for 11 of the 16 CHC domains. The average heritability across all SCA is 56%, similar to that of g. However, there is substantial differential heritability across SCA and SCA do not show the developmental increase in heritability seen for g. We also investigated SCA independent of g (SCA.g). A surprising finding is that SCA.g remain substantially heritable (53% on average), even though 25% of the variance of SCA that covaries with g has been removed. Our review highlights the need for more research on SCA and especially on SCA.g. Despite limitations of SCA research, our review frames expectations for genomic research that will use polygenic scores to predict SCA and SCA.g. Genome-wide association studies of SCA.g are needed to create polygenic scores that can predict SCA profiles of cognitive abilities and disabilities independent of g.

Keywords: Specific cognitive abilityIntelligencemeta-analysisTwin studyHeritability

4. Discussion

Although g is one of the most powerful constructs in the behavioural sciences (Jensen, 1998), there is much to learn about the genetics of cognitive abilities beyond g. Our meta-analysis of 747,567 twin comparisons yielded four surprising findings. One of the most interesting findings about g is that its heritability is similar to that of SCA. The heritability of g is about 50% (Knopik et al., 2017) and the average heritability of SCA from our meta-analysis is 56%.

We focused on three additional questions: Are some SCA more heritable than others (differential heritability)? Does the heritability of SCA increase during development as it does for g? What is the heritability of SCA independent of g?

4.1. Differential heritability

We conclude that some SCA are more heritable than others. The estimates ranged from 39% for auditory processing (Gt) to 64% for quantitative knowledge and processing speed (Gs). Our expectation that domains conceptually closer to g would have higher heritability than ones more conceptually distinct from g led us to be surprised which SCA were most heritable.

For example, we hypothesised that acquired knowledge would be less heritable than fluid reasoning. This is because acquired knowledge is a function of experience, while fluid reasoning involves the ability to solve novel problems. To the contrary, our results indicate that acquired knowledge is the most heritable grouping of CHC domains, with an average heritability of 58%. In contrast, fluid reasoning has a comparatively low heritability estimate of 40%.

We were also surprised to find significantly large differences in heritability between SCA within the same functional grouping. For example, processing speed (Gs), one of the most heritable CHC domains, is within the functional grouping of general speed. Processing speed is defined as ‘the ability to automatically and fluently perform relatively easy or over-learned elementary cognitive tasks, especially when high mental efficiency (i.e., attention and focused concentration) is required’ (McGrew, 2009, p. 6). In contrast, reaction and decision speed (Gt), another CHC domain within the functional grouping of general speed for which twin comparisons were available, yielded one of the lowest heritabilities of 42%. It is defined as ‘the ability to make elementary decisions and/or responses (simple reaction time) or one of several elementary decisions and/or responses (complex reaction time) at the onset of simple stimuli’ (McGrew, 2009, p. 6). Why is reaction and decision speed (Gt) so much less heritable than processing speed (Gs) (42% vs 64%)? One possibility is that processing speed picks up ‘extra’ genetic influence because it involves more cognitive processing than reaction time, as suggested by their definitions. Moreover, Schneider and McGrew (2018) propose a hierarchy of speeded abilities (Kaufman, 2018, p. 108) in which Gs (which they call broad cognitive speed) has a higher degree of cognitive complexity than Gt (broad decision speed). But this would not explain why processing speed is more heritable than fluid reasoning (40%), which seems to involve the highest level of cognitive processing such as problem solving and inductive and deductive reasoning.

One direction for future research is to understand why some SCA are more heritable than others. A first step in this direction is to assess the extent to which differential reliability underlies differential heritability because reliability, especially test-retest reliability rather than internal consistency, creates a ceiling for heritability. For example, the least heritable SCA is short-term memory (Gsm), for which concerns about test-retest reliability have been raised (Waters & Caplan, 2003).

If differential reliability is not a major factor in accounting for differential heritability, a substantive direction for research on SCA is to conduct multivariate genetic analyses investigating the covariance among SCA to explore the genetic architecture of SCA. This would be most profitable if these analyses also included g, as discussed below (SCA.g).

4.2. Developmental changes in SCA heritability

One of the most interesting findings about g is that its heritability increases linearly from 20% in infancy to 40% in childhood to 60% in adulthood. SCA show average decreases in heritability from childhood to later life (column 1 in Fig. 4). Although several CHC domains show increases from early childhood (0–6 years) to middle childhood (7–11 years), this seems likely to be due at least in part to difficulties in reliably assessing cognitive abilities in the first few years of life.

It is puzzling that heritability increases developmentally for g but not for SCA because g represents what is in common among SCA. A previous meta-analysis that investigated cognitive aging found that the heritability of verbal ability, spatial ability and perceptual speed decreased after the age of around 60 (Reynolds & Finkel, 2015). While we did not find evidence for this for any of the SCA domains, we did observe the general trend of decreasing heritability for reading and writing (Grw) and visual processing (Gv) from middle childhood onwards.

We hoped to investigate the environmental hypothesis proposed by Kovas et al. (2013) to account for their finding that the heritability of literacy and numeracy SCA were consistent throughout the school years (∼65%), whereas the heritability of g increased from 38% age 7 to 49% at age 12 (Kovas et al., 2013). They hypothesised that universal education for basic literacy and numeracy skills in the early school years reduces environmental disparities, which leads to higher heritability as compared to g, which is not a skill taught in schools.

We hoped to test this hypothesis by comparing SCA that are central to educational curricula and those that are not. For example, reading and writing (Grw), quantitative knowledge (Gq) and comprehension-knowledge (Gc) are central to all curricula, whereas other SCA are not explicitly taught in schools, such as auditory processing (Ga), fluid reasoning (Gf), processing speed (Gs), short-term memory (Gsm) and reaction and decision speed (Gt). Congruent with the Kovas et al. hypothesis, Grw, Gq and Gc yield high and stable heritabilities of about 60% during the school years. However, too few twin comparisons are available to test whether Ga, Gf, Gs, Gsm and Gt show increasing heritability during the school years.

4.3. SCA independent of g (SCA.g)

Although few SCA.g data are available, they suggest another surprising finding. In these studies, SCA independent of g are substantially heritable, 53%, very similar to the heritability estimate of about 50% for SCA uncorrected for g. This finding is surprising because a quarter of the variance of SCA is lost when SCA are corrected for g. More SCA.g data are needed to assess SCA issues raised in our review about the influence of g in differential heritability and developmental changes in heritability.

Although more data on SCA.g are needed, our preliminary results are encouraging in suggesting that genetic influence on SCA does not merely reflect genetic influence on g. Although g drives much of the predictive power of cognitive abilities, it should not overshadow the potential for SCA to predict profiles of cognitive strengths and weaknesses independent of g.

An exciting aspect of these findings is their implication for research that aims to identify specific inherited DNA differences responsible for the heritability of SCA and especially SCA.g. Genome-wide association (GWA) methods can be used to assess correlations across millions of DNA variants in the genome with any trait and these data can be used to create a polygenic score for the trait that aggregates these weighted associations into a single score for each individual (Plomin, 2018). The most powerful polygenic scores in the behavioural sciences are derived from GWA analyses for the general cognitive traits of g (Savage et al., 2018) and educational attainment (Lee et al., 2018; Okbay et al., 2022). It is possible to use these genomic data for g and educational attainment to explore the extent to which they can predict SCA independent of g and educational attainment even when SCA were not directly measured in GWA analyses, an approach called GWAS-by-subtraction (Demange et al., 2021), which uses genomic structural equation modeling (Grotzinger et al., 2019). We are also employing a simpler approach using polygenic scores for g and educational attainment corrected for g, which we call GPS-by-subtraction (Procopio et al., 2021).

Ultimately, we need GWA studies that directly assess SCA and especially SCA.g. Ideally, multiple measures of each SCA domain would be used and a general factor extracted rather than relying on a single test of the domain. The problem is that GWA requires huge samples to detect the miniscule associations between thousands of DNA variants and complex traits known to contribute to their heritabilities. The power of the polygenic scores for g and educational attainment comes from their GWA sample sizes of >250,000 for g and more than three million for educational attainment. It is daunting to think about creating GWA samples of this size for tested SCA as well as g in order to investigate SCA.g. However, a cost-effective solution is to create brief but psychometrically valid measures of SCA that can be administered to the millions of people participating in ongoing biobanks for whom genomic data are available. For example, a gamified 15-min test has been created for this purpose to assess verbal ability, nonverbal ability and g (Malanchini et al., 2021). This approach could be extended to assess other SCA and SCA.g.

We conclude that SCA.g are reasonable targets for genome-wide association studies, which could enable polygenic score predictions of profiles of specific cognitive strengths and weaknesses independent of g (Plomin, 2018). For example, SCA.g polygenic scores could predict, from birth, aptitude for STEM subjects independent of g. Polygenic score profiles for SCA.g could be used to maximise children's cognitive strengths and minimise their weaknesses. Rather than waiting for problems to develop, SCA.g polygenic scores could be used to intervene to attenuate problems before they occur and help children reach their full potential.

4.4. Other issues

An interesting finding from our review is that SCA.g scores in which SCA are corrected phenotypically for g by creating residualised scores from the regression of g on SCA yield substantially higher estimates of heritability than SCA.g derived from Cholesky analyses.

We suspect that the difference is that regression-derived SCA.g scores remove phenotypic covariance with g, thus removing environmental as well as genetic variance associated with g. In contrast, Cholesky-derived estimates of the heritability of SCA independent of g are calibrated to the total variance of SCA, not to the phenotypic variance of SCA after g is controlled. Regardless of the reason for the lower Cholesky-derived estimates of the heritability of g as compared to regression-derived SCA.g scores, regression-derived phenotypic scores of SCA.g are likely the way that phenotypic measures of SCA will be used in phenotypic and genomic analyses. Instead, the Cholesky models involve latent variables that cannot be converted to phenotypic scores for SCA.g.

Another finding from our review is that heritability appears to be due to additive genetic factors. The average weighted MZ and DZ correlations across the 11 CHC domains for which twin comparisons were available were 0.72 and 0.44, respectively. This pattern of twin correlations, which is similar to that seen across all SCA as well as g, is consistent with the hypothesis that genetic influence on cognitive abilities is additive (Knopik et al., 2017). Additive genetic variance involves genetic effects that add up according to genetic relationships so that if heritability were 100%, MZ twins would correlate 1.0 and DZ twins would correlate 0.5 as dictated by their genetic relatedness. In contrast, if genetic effects operated in a non-additive way, the correlation between DZ twins would be less than half the correlation between MZ twins. Because MZ twins are identical in their inherited DNA sequence, only MZ twins capture the entirety of non-additive interactions among DNA variants. In other words, the hallmark of non-additive genetic variance for a trait is that the DZ correlation is less than half the MZ correlation. None of the SCA show this pattern of results (Fig. 3), suggesting that genetic effects on SCA are additive.

Finding that genetic effects on SCA are additive is important for genomic research because GWA models identify the additive effects of each DNA variant and polygenic scores sum these additive effects (Plomin, 2018). If genetic effects were non-additive, it would be much more difficult to detect associations between DNA variants and SCA. The additivity of genetic effects on cognitive abilities is in part responsible for the finding that the strongest polygenic scores in the behavioural sciences are for cognitive abilities (Allegrini et al., 2019) (Cheesman et al., 2017) (Plomin et al., 2013).

4.5. Limitations

The usual limitations of the twin method apply, although it should be noted that twin results in the cognitive domain are supported by adoption studies (Knopik et al., 2017) and by genomic analyses (Plomin & von Stumm, 2018).

As noted earlier, a general limitation is that some CHC categories have too few studies to include in meta-analyses. This is especially the case in the developmental analyses. Power is diminished by dividing the twin comparisons into five age categories. In addition, different measures are used at different ages; even when measures with the same label are used across ages, they might measure different things. Finally, the developmental results are primarily driven by cross-sectional results from different studies. Nonetheless, longitudinal comparisons within the same study have also found no developmental change in heritability estimates for some SCA (Kovas et al., 2013).

Another limitation of this study is that there might be disagreement concerning the CHC categories to which we assigned tests. We reiterate that we used the CHC model merely as a heuristic to make some sense of the welter of tests that have been used in twin studies, not as a definitive assignment of cognitive tests to CHC categories. We hope that Supplementary Table S-3 with details about the studies and measures will allow researchers to categorise the tests differently or to focus on particular tests. This limitation is also a strength of our review in that it points to SCA for which more twin research is needed. The same could be said for other limitations of SCA twin research such as the use of different measures across studies and the absence of any twin research at some ages.

A specific limitation of SCA.g is that removing all phenotypic covariance with g might remove too much variance of SCA, as mentioned in the Introduction. A case could be made that bi-factor models (Murray & Johnson, 2013) or other multivariate genetic models (Rijsdijk, Vernon, & Boomsma, 2002) would provide a more equitable distribution of variance between SCA and g indexed as a latent variable representing what is in common among SCA. However, the use of bifactor models is not straightforward (Decker, 2021). Moreover, phenotypic and genomic analyses of SCA.g are likely to use regression-derived SCA.g scores because bifactor models, like Cholesky models, involve latent variables that cannot be converted to phenotypic scores for SCA.g.

Finally, in this paper we did not investigate covariates such as average birth year of the cohort, or country of origin, nor did we examine sex differences in differential heritability or in developmental changes in heritability or SCA.g. Opposite-sex DZ twins provide a special opportunity to investigate sex differences. We have investigated these group differences in follow-up analyses (Zhou, Procopio, Rimfeld, Malanchini, & Plomin, 2022).

4.6. Directions for future research

SCA is a rich territory to be explored in future research. At the most general level, no data at all are available for five of the 16 CHC broad categories. Only two of the 16 CHC categories have data across the lifespan.

More specifically, the findings from our review pose key questions for future research. Why are some SCA significantly and substantially more heritable than others? How is it possible that SCA.g are as heritable as SCA? How is it possible that the heritability of g increases linearly across the lifespan, but SCA show no clear developmental trends?

Stepping back from these specific findings, for us the most far-reaching issue is how we can foster GWA studies of SCA.g so that we can eventually have polygenic scores that predict genetic profiles of cognitive abilities and disabilities that can help to foster children's strengths and minimise their weaknesses.

Are people more averse to microbe-sharing contact with ethnic outgroup members? It seems not.

Are people more averse to microbe-sharing contact with ethnic outgroup members? A registered report. Lei Fan, Joshua M. Tybur, Benedict C. Jones. Evolution and Human Behavior, September 22 202. https://doi.org/10.1016/j.evolhumbehav.2022.08.007

Abstract: Intergroup biases are widespread across cultures and time. The current study tests an existing hypothesis that has been proposed to explain such biases: the mind has evolved to interpret outgroup membership as a cue to pathogen threat. In this registered report, we test a core feature of this hypothesis. Adapting methods from earlier work, we examine (1) whether people are less comfortable with microbe-sharing contact with an ethnic outgroup member than an ethnic ingroup member, and (2) whether this difference is exacerbated by additional visual cues to a target's infectiousness. Using Chinese (N = 1533) and British (N = 1371) samples recruited from the online platforms WJX and Prolific, we assessed contact comfort with targets who were either East Asian or White and who were either modified to have symptoms of infection or unmodified (or, for exploratory purposes, modified to wear facemasks). Contact comfort was lower for targets modified to have symptoms of infection. However, we detected no differences in contact comfort with ethnic-ingroup targets versus ethnic-outgroup targets. These results do not support the hypothesis that people interpret ethnic outgroup membership alone as a cue to infection risk.

5. Discussion

The current study was designed to improve upon van Leeuwen and Petersen (2018), which tested the outgroup-as-pathogen-cue hypothesis using only a small number of male targets and a two-item assessment of contact comfort via an English-language survey with participants recruited from the U.S. and India. Consistent with van Leeuwen and Petersen, but sampling from different populations, using larger stimulus pools and broader assessments of contact comfort, and presenting materials in participants' native languages, we did not detect effects supportive of the outgroup-as-pathogen-cue hypothesis. Nevertheless, many of our other findings were consistent with those from previous studies in the behavioral immune system literature. For example, contact comfort was negatively related to pathogen disgust sensitivity (Tybur et al., 2020; van Leeuwen & Jaeger, 2022), and was lower for faces manipulated to appear infectious relative to those unmanipulated (e.g., van Leeuwen & Petersen, 2018; van Leeuwen & Jaeger, 2022). Hence, while results indicated that people are more motivated to avoid microbe-sharing contact with individuals possessing symptoms of current infection, they did not reveal evidence that people are motivated to avoid microbe-sharing contact with ethnic-outgroup members more than ethnic-ingroup members.

5.1. Do other findings support the outgroup-as-pathogen-cue hypothesis?

We found that ethnic outgroup targets were rated as slightly more likely to have an infectious disease than were ethnic ingroup targets. However, participants reported no greater discomfort with pathogen-risky contact with outgroup members. This finding complements findings suggesting that people are averse to indirect contact with individuals possessing facial disfigurements known to not be symptoms of infection (Ryan et al., 2012). Here, rather than contact avoidance being higher for targets believed to be non-infectious, contact avoidance was no higher for targets believed to be (slightly) more infectious (cf. Petersen, 2017). Thus, such results did not entirely support the outgroup-as-pathogen-cue hypothesis.

We also detected a small relation between contact comfort and perceptions that a target is similar to individuals in the local community (Bressan, 2021). Although perceived similarity has been interpreted as a continuous measure of outgroupness (Bressan, 2021), it can also reflect myriad factors unrelated to group membership (e.g., facial morphology, eye color, etc.). Further, similarity perceptions could reflect outputs of the behavioral immune system rather than inputs into it, if similarity perceptions partially regulate contact. And, while we also detected a relation between contact comfort and reported frequency of contact with members of the target's ethnic group, the pattern was quadratic. Contact comfort was lowest for participants who reported the least previous contact with people of the target's ethnicity. However, it was lower for participants who reported the most contact frequency than it was for people who reported intermediate contact frequency.

5.2. Effects of facemasks

In addition to investigating the effects of group membership and explicit cues of infectious disease on contact comfort, we also tested whether people were more or less comfortable with microbe-sharing contact with targets wearing facemasks. We carried out this latter test because facemasks might be interpreted as indicative of infection risk and/or prosociality, and perhaps differently in a Western versus an East Asian country. Although masked targets were perceived as slightly more likely to be infectious than unmasked targets (and more so among British participants than Chinese participants), we did not detect an effect of facemask wearing on contact comfort. However, the perception of infectiousness of targets wearing a facemask varied across the two samples. As with ethnic outgroups, beliefs about infectiousness in mask wearers might not influence the infection-neutralizing motivations outputted by the behavioral immune system. Alternatively, beliefs about target infectiousness could also be offset by beliefs about the prophylactic effects of facemasks. Future research could distinguish between these possibilities.

5.3. The impact of the COVID-19 pandemic

We collected data in January 2022, when many countries were experiencing a surge in infections caused by the Omicron variants of the SARS-CoV-2 virus. The degree to which pandemic conditions impact the behavioral immune system is an open question (Ackerman, Tybur, & Blackwell, 2021). Nevertheless, this surge – as well as infections over the previous two years – might have led to a general decrease in contact comfort across targets. Even so, any decrease in global contact comfort did not prevent us from observing an effect of infection symptom on contact comfort, nor did it prevent us from observing a relation between pathogen disgust sensitivity and contact comfort (cf. Tybur et al., 2022). Indeed, the relation between pathogen disgust sensitivity and contact comfort observed here (r = −0.28) was nearly identical to that observed in similar studies before the pandemic (e.g., Tybur et al., 2020, r's = −0.22, −0.24, and −0.33 across three studies). The pandemic might have also influenced how masked faces are perceived. Given that wearing a facemask was mandatory in many settings in both the UK and China from 2020 to 2022, the pandemic might have decreased the degree to which a mask is interpreted as providing information regarding infectiousness. Further, the widespread use of facemasks across the world might have also dampened cross-cultural differences in how masks are perceived.

5.4. Limitations and future research

We recruited from the White population in the UK and the East-Asian population in China, and we used White and East-Asian stimuli. Our inferences are thus limited to these two populations, both in terms of targets and perceivers. Some findings suggest that pathogen-avoidance motives only impact antipathy toward members of groups that are sufficiently culturally distant or sufficiently associated with infectious disease (Faulkner et al., 2004; Ji et al., 2019). Even so, UK participants explicitly associated China with infectious disease, as did Chinese participants the UK, perhaps due to the origins of COVID-19 (in the case of China) and the high number of COVID-19 cases in deaths in 2020 and 2021 (in the case of the UK). Further, China and the UK differ markedly along broad cultural variables (Muthukrishna et al., 2020). For these reasons, the UK and China seem they appear suitable for testing even a narrower version of the outgroup-as-pathogen-cue hypothesis that require additional associations between a target group and cultural differences in pathogens. Nevertheless, future work could certainly test the outgroup-as-pathogen-cue hypothesis using different target groups.

We also used only a single cue to infectiousness – a skin condition intended to mimic the appearance of shingles. Naturally, infectious disease can lead to other symptoms, including other skin changes (e.g., pallor, rashes, jaundice), vocal changes (e.g., hoarseness), behavioral changes (e.g., lethargy, coughing). Infectiousness and health status can also be detected via other senses, such as olfaction (e.g., body odor, Sarolidou et al., 2020; Zakrzewska et al., 2020) and audition (e.g., voice; Fasoli, Maass, & Sulpizio, 2018). Future studies could test whether the outgroup-as-pathogen-cue hypothesis applies when targets possess different cues to infectiousness.

To date, the literature examining relations between pathogen-avoidance and intergroup biases has largely focused on phenomena such as explicit prejudice (e.g., Huang, Sedlovskaya, Ackerman, & Bargh, 2011; O'Shea et al., 2019) or implicit attitudes (e.g., Faulkner et al., 2004; Klavina et al., 2011). Less work has focused on whether people treat individual outgroup members as if they pose more of a pathogen threat than individual ingroup members. Results reported here and in van Leeuwen and Petersen (2018) cast doubt on the outgroup-as-pathogen-cue interpretation of relations between disgust sensitivity and, for example, anti-immigrant bias. Future work can naturally use approaches apart from contact-comfort ratings to evaluate the outgroup-as-pathogen-cue hypothesis. In the meantime, the field will benefit from generating and testing other hypotheses for explaining why more pathogen-avoidant individuals might feel more negatively toward outgroups.

Powerlessness Also Corrupts: Lower Power Increases Self-Promotional Lying

Powerlessness Also Corrupts: Lower Power Increases Self-Promotional Lying. Huisi (Jessica) Li, Ya-Ru Chen, John Angus D. Hildreth. Organization Science, Sep 21 2022. https://doi.org/10.1287/orsc.2022.1630

Abstract: The popular maxim holds that power corrupts, and research to date supports the view that power increases self-interested unethical behavior. However, we predict the opposite effect when unethical behavior, specifically lying, helps an individual self-promote: lower rather than higher power increases self-promotional lying. Drawing from compensatory consumption theory, we propose that this effect occurs because lower power people feel less esteemed in their organizations than do higher power people. To compensate for this need to view themselves as esteemed members of their organizations, lower power individuals are more likely to inflate their accomplishments. Evidence from four studies supports our predictions: compared with those with higher power, executives with lower power in their organizations were more likely to lie about their work achievements (Study 1, n = 230); graduate students with lower power in their Ph.D. studies were more likely to lie about their publication records (Study 2, n = 164); and employees with lower power were more likely to lie about having signed a business contract (Studies 3 and 4). Mediation analyses suggest that lower power increased lying because lower power individuals feel lower esteem in their organizations (Study 3, n = 562). Further supporting this mechanism, a self-affirmation intervention reduced the effect of lower power on self-promotional lying (Study 4, n = 536). These converging findings show that, when lies are self-promotional, lower power can be more corruptive than higher power.

Men exhibit much greater variability in energy expenditure than women, being more likely to fall in the extremes

Variability in energy expenditure is much greater in males than females. Lewis G.Halsey et al. Journal of Human Evolution, Volume 171, October 2022, 103229. https://doi.org/10.1016/j.jhevol.2022.103229

Abstract: In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction.

4. Discussion

Our study represents a first exploration of GMV in energy expenditure, a trait that captures the net effect of many morphological, physiological, and behavioral factors. Our results indicate considerable GMV in human energy expenditure in terms of TEE, BEE, and AEE (Table 1; Figure 1, Figure 2), although the data cannot distinguish between the two prominent explanations for GMV, heterogamy and sexual selection, since both explanations predict greater trait variance in males than females. We also found GMV in key measures of body condition associated with energy expenditure: height and in particular fat-free mass (Heymsfield et al., 2007; Pontzer et al., 2021; Table 1). Height and fat-free mass correlate strongly with energy expenditure in humans (Cameron et al., 2016; Hopkins et al., 2016; Thomas et al., 2019), raising the possibility that GMV in energy expenditure is simply a result of the GMV in those morphometric traits. However, while statistically accounting for height and fat-free mass considerably reduced the within-sex variance in all three measures of energy expenditure in both males and females (with no clear, systematic, additional reduction in variance when accounting for fat mass and age), the variance ratio between males and females did not systematically decrease. In fact, statistically accounting for these morphometric variables and age resulted in a slight increase in the male:female variance ratio in all three measures of energy expenditure. In other words, remarkably, even when attempting to compare, with statistics, males and females of the same height, fat-free mass, fat mass, and age, males exhibit far more variation in TEE, BEE, and AEE than do females.

The fact that the considerable GMV in energy expenditure is not explained by variation in age, body morphometrics, and condition—key correlates of energy expenditure (Heymsfield et al., 2007; Pontzer et al., 2021)—indicates that GMV in energy expenditure is affected by other factors. It has long been known that behavioral traits are important drivers of energy expenditure. Indeed, when Lavoisier (1743–1794) first started measuring metabolic rate more than 225 years ago, it became immediately clear that organisms spend a lot more energy when active than when resting (Lighton, 2008). Activity levels are more variable in males than females consistently across diverse cultures (Althoff et al., 2017), along with hours slept per night (Ban and Lee, 2001), hours spent sitting (Parsons et al., 2009), and aerobic capacity (Olds et al., 2006), which probably explains why males have more variable AEE than do females. In turn, this is probably reflected in TEE given that AEE constitutes 33% of TEE in the current sample of adult humans (Careau et al., 2021).

In contrast to AEE, BEE by definition all but eliminates the direct effect of behavior on metabolic measurements. The fact that we observed considerable GMV in BEE, and even after factoring out body size and composition, is particularly surprising (though a similar finding can be calculated for resting energy expenditure in 104 adult males and 155 adult females having adjusted for fat-free mass; Müller et al., 2011, their Table 1). It suggests that males are more variable than females in the maintenance costs of some of the physiological components that underpin BEE and which are not reflected in measures of fat-free mass. Although hormonal differences could be a factor (Wu and O'Sullivan 2011; Wang and Xu, 2019), the proximate explanation must be the energy expenditures of the various physiological components of the body. More than 80% of the interindividual variance in BEE in humans is explained by the major body systems (Müller et al., 2018), and the remaining factors probably include the immune system (Buttgereit et al., 2000; Wolowczuk et al., 2008) and the digestive systems, including the influence of the gut microbiota on anaerobic resting metabolism (Riedl et al., 2017; Müller et al., 2018). Although there is no evidence that the mass-independent energy expenditures of various individual organs exhibit GMV (Müller et al., 2013), key elements of the cardiorespiratory system such as heart mass and lung vital capacity vary in size more in males than females (Lauer et al., 1992; Müller et al., 2011; Wierenga et al., 2017), as do two other energy-demanding systems (Müller et al., 2013), the brain (Wierenga et al., 2017) and the kidneys (Gong et al., 2012; cf. Müller et al., 2011), though probably not the liver (Chouker et al., 2004; Müller et al., 2011; Patzak et al., 2014). The spleen also exhibits GMV (Spielmann et al., 2005; Hosey et al., 2006; Müller et al., 2011), as perhaps does ‘residual mass’ which includes bone, skin, stomach, intestines, and glands (Müller et al., 2013). There is also evidence that mitochondrial energetics in response to low metabolic demands vary more in males, as does the abundance of different mitochondrial proteins in skeletal muscle, although sample sizes are fairly small and such studies are in vitro; thus extrapolation of the findings to resting muscles must be tentative (Miotto et al., 2018; Monaco et al., 2020). Blood parameters more often show GMV than the reverse (Lehre et al., 2009), though two reported measures in that study which one might a priori posit show GMV but exhibit the reverse are thyroid-stimulating hormone and tetraiodothyronine. Core temperature, albeit subtly, also exhibits GMV (Chamberlain et al., 1995).

Even though activity is eliminated from the BEE measurements, GMV in activity might still have an indirect role to play in generating GMV in BEE due to training effects. For example, regular exercise is known to increase heart size, mitochondrial count, and blood volume (McArdle et al., 2015), decrease levels of certain hormones and cytokines (Node et al., 2010; Silverman and Deuster, 2014; Pontzer, 2018), and improve mitochondrial oxidative capacity (Cardinale et al., 2018). One possibility, then, is that males have evolved to exhibit considerably more interindividual variation in AEE than have females, and that this drives greater variability in both BEE and TEE.

High energy expenditure is related to various traits that are arguably attractive to females. High BEE for a given size and body condition could positively correlate with aerobic fitness (Poehlman et al., 1989), cognitive capacity (Goncerzewicz et al., 2022), or organ function (Müller et al., 2018). High AEE is associated with high levels of physical activity, and also strength and muscle mass, characteristics known to be attractive to females or at least associated with gaining access to females (Schulte-Hostedde et al., 2008; Neave et al., 2011; Lidborg et al., 2022), in part because these characteristics signal physical fitness (Sharp et al., 1992), athletic ability, and thus competitiveness (Hugill et al., 2010), and also access to high levels of energy resources (Bonduriansky, 2007). If so, then energy expenditure does have a sexual signal component, which would associate with greater variation in males. In turn, by viewing everyday energy expenditure in adults ultimately as reproductive investment (directly and indirectly; Key and Ross, 1999), some males are investing considerably more energy in (anticipated) reproduction than are others, whereas in contrast, the variation between females in terms of energy investment in their potential reproduction is much smaller.

However, an alternative explanation for GMV in energy expenditure arises through consideration not of why male variation is greater but why female variation is lower. That is, why might females have undergone stabilizing selection—both low and high energy expenditures being selected against over time? Maximal sustained energy expenditure is intrinsically constrained at a fixed multiple of BEE, both in animals (Drent and Daan, 1980; Peterson et al., 1990) and humans (Hammond and Diamond, 1997; Thurber et al., 2019). Thus, people with a higher BEE will tend to be those with a higher maximal sustained energy expenditure. For females, this could be advantageous during lactation because it would allow them to expend more energy on reproduction (Fig. 5A). However, if there is an external constraint on sustained energy expenditure due to limited food supply, then the energy available for female reproduction would follow a peaked function with BEE (Fig. 5B). In turn, females with either high or low BEE would be selected against because this would be associated with submaximal energy being expended on reproduction. Because BEE is the dominant component of nonreproductive energy expenditure, reduced variation in BEE results in reduced variation in TEE when females are not reproducing.

[Figure 5. Conceptual model of energy availability during pregnancy in relation to basal energy expenditure (BEE). A) Sustained maximal energy expenditure is a multiple of BEE. Consequently, the energy potentially available for reproduction (calculated as sustained maximal energy expenditure minus BEE) is higher in females with a higher BEE. B) If food availability is limited, then energy intake can create a limit to sustained maximal energy expenditure (dashed line) and in turn, energy available for reproduction is not only low for females with a low BEE but also for females with a high BEE; it is highest when BEE is an intermediate value. The arrows denote selection against the extremes of low BEE and high BEE. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)]

Although our study indicates that GMV is a robust phenomenon in human energy expenditure, we cannot assume that the magnitude of GMV is consistent across all human populations and cultures. Indeed, there is a tentative indication in the present data that people from non-Western countries exhibit a still substantial but reduced GMV, due to a reduction in male variability (Fig. 4). It could be that there are features of Western cultures/societies that serve to exacerbate or attenuate GMV although what these could be are not immediately obvious (perhaps, for example, more time and money enable the sexes to pursue hobbies and lifestyles, e.g., Stoet and Geary, 2018, that contrast in terms of energy expenditure). Cultural variations in the magnitude of GMV might indicate that heterogamy is at best only part of the underlying mechanism but do not offer evidence for or against sexual selection as a predominant mechanism underlying GMV because sexual selection can have strong cultural components (Nakahashi, 2017).

Reduced spending at advanced ages: It is not feeling financially constrained (the fraction satisfied with their economic situation is considerably higher), but reduced enjoyment of activities with worsening health, widowing, & increasing age

Explanations for the Decline in Spending at Older Ages. Susann Rohwedder, Michael D. Hurd & Péter Hudomiet. NBER Working Paper 30460. September 2022. DOI 10.3386/w30460

Abstract: We use new data from the 2019 wave of the Consumption and Activities Mail Survey to help interpret the observed decline in spending as individuals age. At one extreme, forward-looking individuals optimally chose the decline; at the other, myopic individuals overspent and were forced to reduce spending because they had run out of wealth. Which interpretation is correct has important implications for the measurement of economic preparation for retirement. According to their own assessments, the fraction of respondents feeling financially constrained is lower at advanced ages, and the fraction satisfied with their economic situation is considerably higher at older ages than at ages near retirement. An important mechanism reconciling the evidence of reduced spending and greater economic satisfaction at older ages may be that individuals’ enjoyment of several activities declines with worsening health, widowing, and increasing age, leading to a lessening desire to spend on them. We find strong support for this hypothesis. Nonetheless, close to 20% of those older than 80 report not being satisfied with their financial situation, pointing to heterogeneity in economic security.

Poor writing, not specialized concepts, drives processing difficulty in legal language

Poor writing, not specialized concepts, drives processing difficulty in legal language. Eric Martínez, Francis Mollic, Edward Gibson. Cognition, Volume 224, July 2022, 105070. https://doi.org/10.1016/j.cognition.2022.105070

Abstract: Despite their ever-increasing presence in everyday life, contracts remain notoriously inaccessible to laypeople. Why? Here, a corpus analysis (n ≈10 million words) revealed that contracts contain startlingly high proportions of certain difficult-to-process features–including low-frequency jargon, center-embedded clauses (leading to long-distance syntactic dependencies), passive voice structures, and non-standard capitalization–relative to nine other baseline genres of written and spoken English. Two experiments (N=184) further revealed that excerpts containing these features were recalled and comprehended at lower rates than excerpts without these features, even for experienced readers, and that center-embedded clauses inhibited recall more-so than other features. These findings (a) undermine the specialized concepts account of legal theory, according to which law is a system built upon expert knowledge of technical concepts; (b) suggest such processing difficulties result largely from working-memory limitations imposed by long-distance syntactic dependencies (i.e., poor writing) as opposed to a mere lack of specialized legal knowledge; and (c) suggest editing out problematic features of legal texts would be tractable and beneficial for society at-large.

4. Discussion

Our study aimed to better understand the reason why legal texts can be difficult to understand for laypeople by assessing to what extent: (a) difficult-to-process features that are reportedly common in contracts are in fact present in contracts relative to normal texts, and (b) such features–insofar as they are present–cause processing difficulties for laypeople of different reading levels. Here we discuss in turn the extent to which our results successfully answer these questions, as well as the implications of our results from both a scientific and policy perspective.

With regard to (a), our corpus analysis revealed that features such as center embedding, low-frequency jargon, passive voice and non-standard capitalization–all associated with processing difficulty–were more prevalent in contracts relative to all other texts genres that we looked at. In most cases, this difference was striking. Prior to our study, there had been long-standing speculation and anecdotal accounts of the presence of these features in legal texts, and more recent studies had to some degree identified the prevalence of passive voice (Goźdź-Roszkowski, 2011) and non-standard capitalization (Arbel & Toler, 2020) in legal contracts, either on a smaller scale or with regard to specific types of contracts. Our study provides the first large-scale systematic account of the presence of all of these features in legal texts, both overall and relative to a baseline.

With regard to (b), our experimental study revealed that contracts drafted with all of these features were more difficult to both comprehend and recall than contracts drafted without all of these features, while our analyses of individual linguistic structures revealed that some of the features–such as center-embedding and low-frequency words–present greater difficulties in the context of recall than others, such as passive voice. Although language experience–as measured by ART–predicted comprehension performance, there was no correlation between ART and recall performance, nor was there a significant interaction between register and performance on ART in predicting recall or comprehension. Taken together, these results suggest that these features collectively present processing difficulties for readers of all levels of experience.

From a cognitive science perspective, our results provide insight into the long-puzzling issue of why contracts and other legal texts appear so difficult to understand for laypeople. Some legal theorists have taken the position that “law is a system built upon expert knowledge of technical concepts,” such as habeas corpus, promissory estoppel, and voir dire (Tobia, 2019). As a result, the processing difficulty of legal texts is simply a natural result of not knowing specialized legal concepts. Others have argued that “law is a system built upon ordinary concepts,” such as cause, consent, and best interest (Tobia, 2019; Tobia, 2021). In which case, processing difficulty could be explained by psycholinguistic factors.

Our findings better align with an ordinary concepts account of legal language. Previous work in the general psycholinguistics literature has suggested that center-embedded clauses are difficult to process due to the working memory constraints they impose on readers. Correspondingly, the fact that center-embedded clauses were more than twice as prevalent per sentence in the contract corpus than in the standard-English corpus, and inhibited recall to a greater degree than other features in our experimental study suggests that the cause of the processing difficulty of legal texts may be largely related to working memory costs as opposed to a mere lack of understanding of specialized legal concepts.

Furthermore, if certain concepts are not known by those without expert legal training, then one would not expect to find many words to describe those concepts aside from the low-frequency jargon used by legal experts (just as there are no higher-frequency synonyms for terms such as quark or electron in physics, for example). Consequently, the fact that our corpus analysis revealed that contracts contained even more cases of words with high-frequency synonyms than standard English texts undercuts the view that processing difficulty is driven merely by lack of specialized knowledge. Although it is conceivable that specialized concepts contribute to the perceived processing difficulty of legal texts, our results suggest that insofar as low-frequency legal terminology presents processing difficulty for laypeople, this often results not from unfamiliarity with the concept underlying that terminology but with the terminology itself (such as the phrases ab initio and ex post facto, which in many cases respectively can be simplified to “from the start” and “after the fact”).

From a policy perspective, these findings also provide insight into the long-standing issue of how to ease the processing difficulty of legal texts for laypeople. Efforts to simplify legal language over the last 50 years have focused largely on public legal documents, despite the fact that contracts and other private legal documents are more commonly encountered by laypeople–and increasingly so with the rise of the internet and online terms of service agreements. The fact that contracts contain a stunningly high proportion of features that incur processing difficulty in laypeople that can be feasibly replaced with easier-to-process alternatives underscores the importance for efforts to simplify legal language to not neglect private legal documents. Moreover, the fact that certain features that are common to legal texts–such as center embedding and low-frequency words–appear to inhibit recall to a greater degree than others, such as passive voice, suggests that lawyers interested in simplifying legal texts for the benefit of readers ought to prioritize unpacking clauses into separate sentences and opting for higher frequency synonyms when possible.

The main effect of language experience on comprehension performance suggests that those with less language experience have a harder time understanding legal texts. Given that those with less reading experience as a group tend to be of lower socioeconomic status (Bradley & Corwyn, 2002; Kieffer, 2010), and those of lower SES face greater disenfranchisement from the legal system (Legal Services Corporation, 2017), this suggests that simplifying contracts may have non-trivial access to justice implications, particularly as their prevalence increases. At the same time, the fact that those with higher reading experience also struggled to comprehend and understand contracts written in legalese suggests that redrafting texts into a simpler register would have beneficial effects for those of all reading levels.

To better understand how to integrate these findings, we should aim to understand why lawyers choose to write in such an esoteric manner in the first place. One possibility is that legal language must be written so as to maintain communicative precision. This possibility is undercut by our results and previous findings that show comprehension of legal content with a simplified register (e.g., Masson & Waldron, 1994). While it seems entirely plausible that certain legal jargon is inevitable, our results suggest that in many instances such jargon can be replaced with simpler alternatives that increase recall and comprehension while preserving meaning.

Another possibility is that lawyers choose to write in a complex manner to convey their priorities. For example, if a lawyer prioritizes the user's responsibilities they may focus on making them clear at the expense of other content (e.g., company's obligations). If the lawyer's priorities differ from the reader's priorities they may even do this implicitly as opposed to engaging in an outright “conspiracy of gobbledegook” (Mellinkoff, 2004).

Lastly, lawyers may not choose to write in an esoteric manner. Similar to the “curse of knowledge” (Hinds, 1999; Nickerson, 1999), they may not realize that their language is too complicated for the average reader to understand (Azuelos-Atias, 2018). This hypothesis appears to be supported by previous findings that show an effect of features such as prior knowledge and reading skill on the processing of specialized texts (Cain, Oakhill, & Lemmon, 2004; Kendeou & Van Den Broek, 2007; Long, Prat, Johns, Morris, & Jonathan, 2008; Noordman & Vonk, 1992; Ozuru, Dempsey, & McNamara, 2009). Similarly, one might predict that lawyers would be equally likely to comprehend contracts if they were drafted in an esoteric style as they would if they were drafted in a simpler register, which may render them less able to appreciate the difficulty of these features for those without legal training. Further work into the plausibility of these hypotheses could yield insight into how best to persuade lawyers to integrate the findings of our and similar studies and help alleviate the growing mismatch between the ubiquity and impenetrability of legal texts in the modern era.

The authors explore whether mandatory, universal, in-person sexual misconduct training achieves its goals to build knowledge about sexual assault and harassment and increase intentions to report episodes of assault

Effects of Mandatory Sexual Misconduct Training on University Campuses. Mala Htun et al. Socius, September 20, 2022. https://doi.org/10.1177/23780231221124574

Abstract: The authors explore whether mandatory, universal, in-person sexual misconduct training achieves its goals to build knowledge about sexual assault and harassment and increase intentions to report episodes of assault. The authors present results from three studies with quasi-experimental designs as well as interviews with students and staff members at a diverse public university in the western United States. The surprising finding is that participating in training makes women students less likely to say they that will report experiences of sexual assault to university authorities. The training produces some small positive effects: students gain broader definitions of sexual misconduct and are less likely to endorse common rape myths, and women students express less sexist attitudes immediately after training. This study raises questions about whether one-shot training helps reduce sexual violence and increase reporting on college campuses and whether universities should invest in these types of training.

Discussion

The most striking finding of our study is that women students become less likely to say that they would report experiences of sexual assault after participating in sexual misconduct training. We see a 12 percentage point decline in the share of women who say they would report assault to the university. The share of men who say that they would report assault does not change. In addition, women become more likely to say they would encounter retaliation if they report.

Our results imply that the university’s considerable investments in reporting did not change women’s perceptions of reporting’s desirability and its risks. Women do not all welcome the possibility of reporting assault, and they are more worried about the consequences of reporting than are men. Not reporting allows women to downplay a bad experience, reject the label of victim, and preserve their existing relationships (Khan et al. 2018). Sitting through sexual misconduct training—perhaps by concretizing the meaning of assault for survivors or potential survivors—may actually induce greater resistance to reporting among women.

On the brighter side, we find that training expands student knowledge about, and attitudes toward, sexual assault and harassment in ways intended by the university and the federal government’s Title IX goals. This is potentially important, as changing knowledge and attitudes may be necessary to change the culture surrounding gendered violence on college campuses (Hirsch et al. 2019). However, the effect sizes are small and reflect the training’s immediate impact, as our study design precluded gathering evidence of changes in behavior and attitudes after more time had passed.²³ Future research should probe whether the positive and negative effects of the training endure over the medium to longer term.

In contrast to other work showing that discussions of sexual assault and harassment activate gender stereotypes (e.g. Tinkler 2013), our surveys do not show that training aggravates sexist beliefs. However, we do find that men’s and women’s views on sexism diverge more after the training (see Figure 5). Some of our interviews suggest that for some people—and despite trainers’ gender neutral discourse and avoidance of the male perpetrator–female victim stereotype—the training may have reinforced differences between men and women. For example, one woman student told us she found the training to be “isolating”:

it made everyone feel, like the genders, feel polarized. So, when I walked in there, I was having a comfortable conversation with my neighbor who was a man and by the end it was like we were trying to distance our seats as much as we could from each other.²⁴

The need to comply with federal mandates motivated university officials to develop the training program we studied, as is the case with hundreds of other institutions of higher education around the country. At our study site, the compliance process was intense because of the DOJ oversight agreement. The agreement led to multiple changes in policy and process, which were necessary and overdue, but it also had some detrimental effects on institutional culture.

A senior university leader characterized the challenge of reducing sexual assault on campus in the following way:

How do you solve a problem? Look to other cases of institutional success. [such as our work to increase graduation rates] Leadership took a strong stand and communicated a clear message. We made the issue a priority. We targeted problem cases. We did research and got data [that ruled out what many people thought to be the source of the problem]. . . . But it’s hard to launch this process under the guise of a [federal] investigation, which makes everyone defensive and resentful.²⁵

University administrators had mixed interpretations of how much programming federal guidelines required. As one compliance officer put it, “I have super high expectations of what it means to meet [federal] expectations, but others see it more minimally.”²⁶ Senior university leaders assigned responsibility for sexual violence prevention to certain campus units without giving them the extra staffing and budget that serious efforts require. One administrator of these units noted that the university “is continuing the pattern of marginalization and underfunding of these issues.”²⁷