Human adult neurogenesis seems unlikely: Found signatures of adult neurogenesis in mouse, pig, and macaque dentate gyrus, but not in humans, adding to a growing body of evidence that this process is likely lost in humans

Transcriptomic taxonomy and neurogenic trajectories of adult human, macaque, and pig hippocampal and entorhinal cell. Daniel Franjic et al. Neuron, Volume 110, Issue 3, February 2 2022, Pages 452-469.e14. https://doi.org/10.1016/j.neuron.2021.10.036

Highlights

• Single-nucleus RNA-seq of adult hippocampal-entorhinal cells in human, monkey, and pig

• Transcriptomic signatures of adult neurogenesis in mouse, pig, and monkey but not human

• Excitatory neuron diversification delineates transitions from 3- to 6-layered cortex

• METTL7B defines subregion-specific excitatory neurons and astrocytes in primates

Summary: The hippocampal-entorhinal system supports cognitive functions, has lifelong neurogenic capabilities in many species, and is selectively vulnerable to Alzheimer’s disease. To investigate neurogenic potential and cellular diversity, we profiled single-nucleus transcriptomes in five hippocampal-entorhinal subregions in humans, macaques, and pigs. Integrated cross-species analysis revealed robust transcriptomic and histologic signatures of neurogenesis in the adult mouse, pig, and macaque but not humans. Doublecortin (DCX), a widely accepted marker of newly generated granule cells, was detected in diverse human neurons, but it did not define immature neuron populations. To explore species differences in cellular diversity and implications for disease, we characterized subregion-specific, transcriptomically defined cell types and transitional changes from the three-layered archicortex to the six-layered neocortex. Notably, METTL7B defined subregion-specific excitatory neurons and astrocytes in primates, associated with endoplasmic reticulum and lipid droplet proteins, including Alzheimer’s disease-related proteins. This resource reveals cell-type- and species-specific properties shaping hippocampal-entorhinal neurogenesis and function.

Discussion

We report an extensive single-cell transcriptomics analysis of several anatomically defined cell populations in the adult human, macaque, and pig hippocampal-entorhinal system. Our findings reveal fundamental species differences in adult hippocampal neurogenesis and delineate the molecular diversity of the cytoarchitectural transition from the allo- to the neocortex. These results also outline genes that are selectively enriched in certain species and cell types that may have a role in the specific biology and/or pathology of the hippocampal-entorhinal system

Unlike recent studies that mostly rely on one or two key markers (e.g., progenitors [nestin]; neuroblasts and immature granule cells [DCX]) (Boldrini et al., 2018; Moreno-Jiménez et al., 2019; Tobin et al., 2019), single-cell RNA-seq studies are more comprehensive because they leverage combinatorial gene expression profiles to identify cell populations more robustly (Hochgerner et al., 2018). This approach also allows cross-species analysis, amplifying rare signals within a single species that may be masked when analyzed separately. Our cross-species analysis allowed identification of the neurogenic lineage in the mouse, pig, and macaque, which was virtually absent in the human. We only detected one cell with the transcriptomics profile characteristic of nIPCs and one with putative neuroblast profile among 32,067 granule cells (0.003%) in our adult human DG samples, a proportion considerably lower than the expected 0.09%–3.8% neuroblasts according to previous DCX immunostaining or 14C incorporation studies of the adult human HIP (see Table S2 for data and relevant studies).

The same analytic strategy detected much higher proportions of neuroblasts in the other analyzed species (mouse, 6.6%; pig, 55.6%; macaque, 2.0%; Figure 2B; Table S3). These proportions were higher than those estimated previously based on progenitor proliferation and identification of neuroblasts markers such as DCX (Table S2), suggesting that more studies are needed to fine-tune detection of these neurogenic populations. However, this apparently lax detection protocol confirms that our parameters are unlikely to have missed any appreciable neuroblast populations among the large pool of surveyed human DG granule cells, even if they might exhibit an ambiguous profile.

Alternative confounding of our cross-species integrative analysis from possible human-specific transcriptomics changes was ruled out when human UMAP layouts did not include any clustering of neurogenic cells adjacent to the mature granule cell cluster. Likewise, the possibility that human neuroblasts exist in our samples but that their transcriptomics profile differs from other species and blends with related cell populations is lessened by findings that all neurogenic lineages preceding mature granule cells were absent in human DG samples (Tables S2 and S3).

We also extended our findings to existing snRNA-seq data of the adult human HIP. We reappraised the identity of a recently reported neural progenitor cluster (Ayhan et al., 2021) marked by LPAR1, a gene reported to mark mouse DG neural progenitors (Walker et al., 2016; Hochgerner et al., 2018). Our analyses indicated that this cluster actually represented doublets formed by oligodendrocytes and granule cells (Figure S3S). In addition, reanalysis of the pioneer HIP data (Habib et al., 2017) by Sorrells et al. (2021) showed that the cell cluster labeled as neural stem cells was actually characteristic of ependymal cells.

Analysis of DCX transcripts in all the analyzed species showed expression in mature neurons, mostly InNs, and in glial cells, indicating that DCX expression is not exclusive to DG neuroblasts (Figures 3A and 3B). This pattern is in agreement with the reanalysis of the data from Habib et al. (2017) (Sorrells et al., 2021). All transcriptomics analyses performed so far suggest a lack of neurogenic cell populations in the adult human DG.

At the protein level, DCX was, with a few exceptions (Figure S3L), present exclusively in DG cells resembling neuroblasts and immature granule cells in all analyzed non-human species. Also, cells with immature morphology could be detected in other areas, such as the EC of the macaque or the pyriform cortex of the mouse, as described previously (Gómez-Climent et al., 2008; Zhang et al., 2009). In humans, there is intense controversy regarding DCX immunostaining in the human DG, with some reports showing negative results (Dennis et al., 2016; Cipriani et al., 2018; Sorrells et al., 2018, 2021) and others describing DCX-IL cells (Knoth et al., 2010; Epp et al., 2013; Boldrini et al., 2018; Le Maître et al., 2018; Moreno-Jiménez et al., 2019, 2021; Tobin et al., 2019). We detected clear DCX-IL cells in the amygdala and occasionally in the EC, but we could not find DCX-IL cells resembling neuroblasts in the DG in the same tissue sections. These inconsistencies in detecting DCX-IL cells in the adult human DG cannot be fully attributed to postmortem denaturation and degradation of DCX protein because DCX-IL cells were clearly detected in samples with prolonged PMIs (Figures S3D, S3E, and S3I–S3L). Moreno-Jiménez et al. (2019) reported an intensive protocol for antigen retrieval as a necessary step to label DCX cells in the human DG. However, they reported no positive cells in the EC, a relatively common finding in our study (Figure S3D) and another (Sorrells et al., 2021) using conventional antigen retrieval. Because our analysis did not reveal neuroblasts at the RNA or protein level (using diverse antigen retrieval methods), the question remains what those previously reported cells could be. Apart from underappreciated non-specific and off-target effects (Sorrells et al., 2021), those studies could label mature granule cells and InNs that might contain low levels of DCX protein that was detected specially after multi-step antigen retrieval. In support of this hypothesis is the fact that the faintly immunolabeled cells we detected mostly in the vicinity of the granule cell layer, exhibited the morphology of mature InNs, and some co-labeled with antibodies against GAD1, a marker of InNs (Figures 3E and S3M–S3Q). This faint staining is far from the strong staining and well-defined morphology of somata and dendrites revealed in the EC and in the amygdala (Figures S3D and S3E) and is similar to the light DCX immunostaining reported previously (Seki et al., 2019). Thus, our conclusion is that DCX protein might be expressed at very low levels in InNs or in some mature granule cells that can be lightly immunolabeled under normal antigen retrieval but can show more intense and widespread staining under more elaborate tissue treatment and stringent conditions of antigen retrieval. In fact, Figure 2I from Moreno-Jiménez et al. (2019) shows that around 75% of DCX-IL cells were colocalized with NeuN (RBFOX3, 75%), a marker of mature granule cells, and 91% of DCX-IL cells were also positive for Prospero homeobox1 (PROX1), a transcription factor expressed by granule cells that is also expressed by InNs generated in the caudal ganglionic eminence (Ma et al., 2013; Laclef and Métin, 2018), supporting the possibility that most DCX-IL cells might actually be mature granule cells or InNs.

Regarding RNA analysis, although the PMI for humans was longer than for other analyzed species, human brains were kept at 4°C for most of the PMI period, whereas the pigs used as controls for PMI were kept at room temperature. This warm PMI will likely exacerbate the postmortem effects, but those conditions were not an obstacle to detect the neurogenic pathway in this species. It could be argued that the neurogenic pathway in the human DG is not detected because our snRNA-seq strategy might preferentially exclude neurogenic cells in humans. However, it seems extremely unlikely that it will affect all cell types in the neurogenic lineage, from progenitors to neuroblasts, and only in human. Overall, the most parsimonious interpretation of the combined results from our RNA transcript analysis and the DCX protein study is that, contrary to the other analyzed mammals, ongoing baseline neurogenesis does not occur or is extremely rare in the adult human DG.

Similar species-related and cell-specific transcriptomics profiling that characterizes neurogenic potential also outlines the transition from allocortical to neocortical domains in the hippocampal-entorhinal system and shows that ExNs are the main drivers of the differences between subfields (Figure 4), which evidences a richer complement of ExNs than traditional descriptions based on cytoarchitecture. Our analysis provides a primer to further study these populations and characterize the possible implications for hippocampal-entorhinal physiology. These data refine our understanding of the evolution of the allo-, meso-, and neocortex. The transcriptomics signatures we developed strongly suggest homology between the mammalian allocortex and specifically deep layers of the EC and neocortex.

Among the genes contributing to the layer transition, we identified METTL7B to be important in hippocampus physiology and function. We found that METTL7B, equipped with methyltransferase activity, interacts with important AD-related proteins (e.g., APP, LRP1, RTN3, and RTN4). Importantly, our results suggest that these functional interactions in a subset of ExNs and astrocytes seem to be phylogenetically specific to Old World monkeys and apes (parvorder Catarrhini), species that show more marked signs of pathology related to aging, such as AD, than other species (Perez et al., 2013; Finch and Austad, 2015; Edler et al., 2017; Paspalas et al., 2018). Overall, our analyses provide multiple vignettes of how this resource can be used to identify cell types and genes that might be functionally relevant for the biology of the hippocampus, allowing inter-species comparisons.

Nudges: Our megastudy with 689,693 Walmart pharmacy customers demonstrates that text-based reminders can encourage pharmacy vaccination

A 680,000-person megastudy of nudges to encourage vaccination in pharmacies. Katherine L. Milkman et al. Proceedings of the National Academy of Sciences, February 8, 2022 119 (6) e2115126119; https://doi.org/10.1073/pnas.2115126119

Significance: Encouraging vaccination is a pressing policy problem. Our megastudy with 689,693 Walmart pharmacy customers demonstrates that text-based reminders can encourage pharmacy vaccination and establishes what kinds of messages work best. We tested 22 different text reminders using a variety of different behavioral science principles to nudge flu vaccination. Reminder texts increased vaccination rates by an average of 2.0 percentage points (6.8%) over a business-as-usual control condition. The most-effective messages reminded patients that a flu shot was waiting for them and delivered reminders on multiple days. The top-performing intervention included two texts 3 d apart and stated that a vaccine was “waiting for you.” Forecasters failed to anticipate that this would be the best-performing treatment, underscoring the value of testing.

Abstract: Encouraging vaccination is a pressing policy problem. To assess whether text-based reminders can encourage pharmacy vaccination and what kinds of messages work best, we conducted a megastudy. We randomly assigned 689,693 Walmart pharmacy patients to receive one of 22 different text reminders using a variety of different behavioral science principles to nudge flu vaccination or to a business-as-usual control condition that received no messages. We found that the reminder texts that we tested increased pharmacy vaccination rates by an average of 2.0 percentage points, or 6.8%, over a 3-mo follow-up period. The most-effective messages reminded patients that a flu shot was waiting for them and delivered reminders on multiple days. The top-performing intervention included two texts delivered 3 d apart and communicated to patients that a vaccine was “waiting for you.” Neither experts nor lay people anticipated that this would be the best-performing treatment, underscoring the value of simultaneously testing many different nudges in a highly powered megastudy.

Keywords: vaccinationCOVID-19nudgeinfluenzafield experiment

Discussion

The results of this megastudy suggest that pharmacies can increase flu vaccination rates by sending behaviorally informed, text-based reminders to their patients. Further, although all interventions tested increased vaccination rates, there was significant variability in their effectiveness. Attribute analyses suggest that the most-impactful interventions employed messages sent on multiple days and conveyed that a flu vaccine was already waiting for the patient. These insights from our megastudy of flu vaccinations can potentially inform efforts by pharmacies and hopefully also providers and governments around the world in the ongoing campaign to encourage full vaccination against COVID-19.

The first- and second-best-performing messages in our megastudy repeatedly reminded patients to get a vaccine and stated that a flu shot was “waiting for you.”§ This aligns with prior research suggesting multiple reminders can help encourage healthy decisions (13). In terms of message content, communicating that a vaccine is “waiting for you” may increase the perceived value of vaccines, in accord with research on the endowment effect showing that we value things more if we feel they already belong to us (33). Further, because defaults convey implicit recommendations, this message may imply that the pharmacy is recommending vaccination (34)—otherwise, why would they have allocated a dose to you? Relatedly, this phrasing implies that the patient already agrees that getting the vaccine is desirable. Finally, saying a vaccine is “waiting for you” may suggest that getting a vaccine will be fast and easy.

Remarkably, the three top-performing text messages in a different megastudy, which included different intervention messages encouraging patients to get vaccines at an upcoming doctor’s visit, similarly conveyed to patients that a vaccine was “reserved for you.” (8) The Walmart megastudy tested a wide range of different messaging tactics designed by different researchers to explore largely different hypotheses such that the two megastudies had very limited overlap in their content. Further, our outcome variable here was electing to get a vaccine in a Walmart pharmacy, whereas the prior megastudy examined whether patients accepted a proffered vaccine in a doctor’s office. Despite differences in the messenger (pharmacy versus primary care provider), the outcome (seeking a vaccine at a pharmacy versus passively accepting one in a doctor’s office), and the messages actually tested, and despite analyzing our data without incorporating any priors, the results of the two megastudies converged, painting a consistent picture of what works. Together, this evidence suggests that sending reminder messages conveying that vaccines are “reserved” or “waiting” for patients is an especially effective communications strategy in the two most-common vaccination settings in the United States (16). While more research is needed to establish boundary conditions, it is notable that a follow-up study that built on the findings from these two megastudies and adapted the best-performing treatment to nudge COVID-19 vaccinations in the winter of 2021 found convergent results (9).

The scientists who designed interventions in our megastudy were not able to accurately forecast the average or relative performance of text message interventions designed to boost vaccinations. In contrast, lay survey respondents made fairly accurate predictions of both. This contradicts past research showing that experts are generally better at predicting the effectiveness of behavioral interventions than nonexperts (35). One possible explanation is that direct involvement in the design of interventions led to bias. Another possibility is that nonexperts are generally more-accurate relative forecasters in this particular field setting. Regardless, the inability of either scientists or laypeople to anticipate the top-performing intervention underscores the value of empirical testing when seeking the best policy.

The strengths of this megastudy include its massive, national sample, statistical power, an objective measure of vaccination obtained longitudinally over a 3-mo follow-up period, and simultaneous comparison of many different interventions. Several important weaknesses are also worth noting. First, we were only able to measure the impact of our interventions on vaccinations received at Walmart pharmacies. We cannot assess whether interventions increased vaccinations in other locations or, in fact, crowded out vaccinations in other settings. Past research found no meaningful evidence of crowd-in or crowd-out from reminder messages nudging vaccine adoption (4), but we cannot rule out either possibility. Another limitation is that the population studied only included patients who had received an influenza vaccine at a Walmart pharmacy in the prior flu season and agreed to receive SMS communications from Walmart pharmacy. Even so, our key findings are consistent with a different megastudy nudging vaccination at doctors’ visits (8), in which results were not moderated by prior vaccination status. It would be ideal to replicate and extend this megastudy with patients who have no prior history of vaccination. Relatedly, while we did not observe meaningful heterogeneity in treatment effects by available demographics, future research exploring heterogeneous treatment effects with a richer set of individual difference variables would be valuable.

Men are less religious in more gender-equal countries

Men are less religious in more gender-equal countries. Jordan W. Moon, Adam E. Tratner and Melissa M. McDonald. Proceedings of the Royal Society B: Biological Sciences, February 2 2022. https://doi.org/10.1098/rspb.2021.2474

Abstract: Sex differences in religiosity are cross-culturally common and robust, yet it is unclear why sex differences in some cultures are larger than in others. Although women are more religious than men in most countries, religions frequently provide asymmetrical benefits to men at the expense of women. Two global analyses (51 countries and 74 countries) found that country-level gender equality was consistently and negatively associated with religiousness (i.e. religious attendance, reported importance of God and frequency of prayer) for men, more than for women, leading to a larger sex difference in religiousness in more gender-equal countries. Results were especially robust for religious attendance, and hold accounting for country-level wealth, as well as individuals' religious affiliation, the moralization of sexuality, age and education level. We interpret results through a rational choice lens, which assumes that people are more drawn to religion when it is consistent with their reproductive goals.

4. Discussion

These data show that gender equality across cultures consistently and negatively predicts religious belief and behaviour among men, but the effect is small and inconsistent for women. This interaction between gender equality and participant sex holds in most of the models we ran, even when accounting for the clustering of countries within sub-regions, the religious denominations of participants, sociosexuality, age, education and country-level wealth.

The results were particularly strong with religious attendance as an outcome; in all such models there was a consistent negative relationship between gender equality and religious attendance for men, but no effect for women. We suggest that religious attendance (versus private religious behaviour or belief) is the outcome most relevant to our hypothesis. That is, it is attendance and overt participation that we would expect to be associated with the reproductive outcomes of interest. Overt religious participation may allow men to more easily monitor women, police sexual behaviour or to signal their value as a mate via religious commitment.

In addition, the focal results were driven by gender equality in education and economic participation, but not political power or health/survival. These results could be consistent with the view of religion as a ‘costly signal’ to indicate qualities such as trustworthiness, dedication to one's family or even simply dedication to one's group [7,37–39,62–64]; gender equality might also influence the payoffs of using religion as a costly signal. For instance, there is some evidence that women's economic dependence on men—which makes paternal certainty more critical—facilitates moralization of promiscuity [65]. It follows, then, that women who are dependent on men (i.e. when gender equality is low) may prioritize signals of paternal investment and long-term commitment; this could, in turn, incentivise men in these societies to use religion as a signal of their willingness to invest in their offspring [7,39].

One could also predict the same pattern by considering other functions of religion. For example, religion fosters cooperation and ingroup cohesion [66,67] and can help people manage their existential insecurities [41]. Indeed, religions are especially attractive to people after facing mortal threats, such as intergroup conflict [68]. One alternative explanation, then, could be that countries that have achieved greater gender equality face fewer threats that require male coalitional coordination (e.g. warfare); therefore, people (particularly men) in these countries are less likely to view religion as necessary. We reiterate, however, that our analyses are unable to reveal the mechanism behind the observed effects, or to adjudicate between alternative explanations.

Our hypothesis stems from a rational choice perspective on religion [9], suggesting that engagement in religious behaviours and beliefs might stem partly from the reproductive benefits people acquire from them [9,16,18]. Because religions often involve costly behaviour [69,70], one should expect religious engagement to be more likely when the benefits outweigh the costs. If indeed one of the functions of religion is reproductive support that often favours men over women, and if the manipulation of women in such ways (e.g. through modesty norms or proscribing sexual promiscuity) is less accepted in more gender-equal societies, the costs may outweigh the benefits for men in these societies, resulting in lower religiousness among men.

Feminist-identified men were substantially more likely to report Erectile Dysfunction Medication use than non-feminist men; could be that feminist men are more honest about this usage, or that non-feminist ones see using it as a threat to masculinity

Silva, Tony, and Tina Fetner. 2022. “Men’s Feminist Identification and Reported Use of Prescription Erectile Dysfunction Medication.” SocArXiv. February 1. doi:10.1080/00224499.2022.2029810

Abstract: We analyzed data from the 2018 Sex in Canada survey (n = 1,015 cisgender men) to examine the association between feminist identification and reported use of prescription ED medication (EDM) during men’s last sexual encounter. Feminist-identified men were substantially more likely to report EDM use than non-feminist men, even after controlling for alcohol use before sex, erection difficulties, sexual arousal, sexual health, mental health, and physical health. One explanation is that feminist men may use EDM to bolster their masculinity when it is otherwise threatened by their identification as feminist. Another is that non-feminist men may be less likely to use prescription EDM because they view accessing healthcare services as a threat to their masculinity. It is also possible that feminist men are more likely to use EDM because they wish to maintain an erection to better please their partner. Lastly, feminist men may be more honest about EDM use than non-feminist men, even though rates are similar. Regardless of the exact reason, therapists can use these results to tailor sexual health messages to clients based on feminist identification. Future work could employ qualitative methods to understand why feminist men report higher rates of EDM use than non-feminist men.

The size and homophily of friendship networks are to a substantial degree based on genetic influence; no evidence found that shared hobbies, education, or Big Five personality traits affect networks

Heritability in friendship networks. Michael Neugart, Selen Yildirim. Journal of Economic Behavior & Organization, Volume 194, February 2022, Pages 41-55. https://doi.org/10.1016/j.jebo.2021.12.008

Highlights

• Heritability of overall friendship network characteristics is explored.

• Data from German TwinLife Study is analyzed within classical twin design.

• Genetic component found in twins’ network size and network homophily.

• Role of twins’ shared hobbies, education, and personality traits is analyzed.

Abstract: There is considerable evidence nowadays that friendship networks account for a large part of an individual’s success or failure in life. Little, however, is known about the extent to which friendship networks are associated with an individual’s genotype. Using data from the German TwinLife study, we explore, within a classical twin design, whether friendship networks are related to genes. We find a substantial heritability component in twins’ network sizes and network homophily, but not in twins’ network closeness. The genetic influence on network characteristics may be attributable to traits which are themselves influenced by genetic factors. Addressing indirect ways in which genes could influence network characteristics, we do not find evidence that shared hobbies, education, or Big Five personality traits affect networks.

Keywords: Social networksTwinsBehavioral geneticsHobbiesBig fiveEducation

Heterosexual women's exposure to a same-sex peer who constituted a sexual rival (straight/bisexual) led to more spreading of reputation-damaging information vs. reputation-enhancing info, compared with exposure to a noncompetitor (lesbian target)

Bakolas, N. K. M., & Park, J. H. (2022). Female intrasexual competition is affected by the sexual orientation of the target and the ovulatory cycle. Evolutionary Behavioral Sciences, Feb 2022. https://doi.org/10.1037/ebs0000287

Abstract: Research suggests that women use indirect aggression strategies to compete with same-sex peers and improve their mating prospects. One such tactic involves strategically transmitting reputation-damaging information as opposed to reputation-enhancing information, to lessen the appeal of sexual rivals. The present study further examined whether this strategic information transmission constitutes an intrasexual competition strategy, by comparing denigration of same-sex peers who constitute sexual competitors or noncompetitors as determined by their sexual orientation. This study also explored the impact of the ovulatory cycle on this strategy, following research suggesting that hormone fluctuation drives subtle behavioral changes near ovulation, amplifying other forms of intrasexual competition between women. Results indicated that among women identifying as straight, exposure to a same-sex peer who constituted a sexual rival (straight/bisexual target) led to greater transmission of reputation-damaging information relative to reputation-enhancing information, compared with exposure to a noncompetitor (lesbian target). The ovulatory cycle was found to be associated with denigration, but this did not depend on the sexuality of the target. Participants in the estimated high-estrogen phase showed greater denigration overall than participants in the low-estrogen phase, regardless of the target’s sexuality.

Women's pick-up lines are perceived as most effective when they are direct and unmistakable, particularly by men

Wade, T. J., Fisher, M. L., & Gaines, L. (2022). The perceived effectiveness of women’s pick-up lines: Do age and personality matter? Evolutionary Behavioral Sciences, Feb 2022. https://doi.org/10.1037/ebs0000286

Abstract: One way to initiate a conversation for the purposes of mate attraction is to use a pick-up line. While past research has addressed men’s use of pick-up lines, there has been far less research on those used by women. Here, we explored the perceived effectiveness of women’s pick-up lines, particularly with regard to one’s age but also as correlated with their Big Five personality factors. We hypothesized that both men and women would rate the same pick-up lines as effective and that older participants would rate pick-up lines as more effective than younger participants. Our results indicate that women’s use of direct pick-up lines, sharing things in common, asking for a phone number, indirectly hinting at a date, and asking if single were perceived as most effective by both sexes. We did not support our prediction about age. The results demonstrate that of the Big Five dimensions, extraversion in particular is important and was positively correlated with perceived effectiveness.

People are more likely to reveal secrets that violate their own moral values; were more willing to reveal immoral secrets as a form of punishment, and this was explained by feelings of moral outrage

Salerno, J. M., & Slepian, M. L. (2022). Morality, punishment, and revealing other people’s secrets. Journal of Personality and Social Psychology, Feb 2022. https://doi.org/10.1037/pspa0000284

Abstract: Nine studies represent the first investigation into when and why people reveal other people’s secrets. Although people keep their own immoral secrets to avoid being punished, we propose that people will be motivated to reveal others’ secrets to punish them for immoral acts. Experimental and correlational methods converge on the finding that people are more likely to reveal secrets that violate their own moral values. Participants were more willing to reveal immoral secrets as a form of punishment, and this was explained by feelings of moral outrage. Using hypothetical scenarios (Studies 1, 3–6), two controversial events in the news (hackers leaking citizens’ private information; Study 2a–2b), and participants’ behavioral choices to keep or reveal thousands of diverse secrets that they learned in their everyday lives (Studies 7–8), we present the first glimpse into when, how often, and one explanation for why people reveal others’ secrets. We found that theories of self-disclosure do not generalize to others’ secrets: Across diverse methodologies, including real decisions to reveal others’ secrets in everyday life, people reveal others’ secrets as punishment in response to moral outrage elicited from others’ secrets.

Handedness in twins: meta-analyses

Handedness in twins: meta-analyses. Lena Sophie Pfeifer, Judith Schmitz, Marietta Papadatou-Pastou, Jutta Peterburs, Silvia Paracchini & Sebastian Ocklenburg. BMC Psychology volume 10, Article number: 11. Jan 15 2022. https://bmcpsychology.biomedcentral.com/articles/10.1186/s40359-021-00695-3

Abstract

Background: In the general population, 10.6% of people favor their left hand over the right for motor tasks. Previous research suggests higher prevalence of atypical (left-, mixed-, or non-right-) handedness in (i) twins compared to singletons, and in (ii) monozygotic compared to dizygotic twins. Moreover, (iii) studies have shown a higher rate of handedness concordance in monozygotic compared to dizygotic twins, in line with genetic factors playing a role for handedness.

Methods: By means of a systematic review, we identified 59 studies from previous literature and performed three sets of random effects meta-analyses on (i) twin-to-singleton Odds Ratios (21 studies, n = 189,422 individuals) and (ii) monozygotic-to-dizygotic twin Odds Ratios (48 studies, n = 63,295 individuals), both times for prevalence of left-, mixed-, and non-right-handedness. For monozygotic and dizygotic twin pairs we compared (iii) handedness concordance Odds Ratios (44 studies, n = 36,217 twin pairs). We also tested for potential effects of moderating variables, such as sex, age, the method used to assess handedness, and the twins’ zygosity.

Results: We found (i) evidence for higher prevalence of left- (Odds Ratio = 1.40, 95% Confidence Interval = [1.26, 1.57]) and non-right- (Odds Ratio = 1.36, 95% Confidence Interval = [1.22, 1.52]), but not mixed-handedness (Odds Ratio = 1.08, 95% Confidence Interval = [0.52, 2.27]) among twins compared to singletons. We further showed a decrease in Odds Ratios in more recent studies (post-1975: Odds Ratio = 1.30, 95% Confidence Interval = [1.17, 1.45]) compared to earlier studies (pre-1975: Odds Ratio = 1.90, 95% Confidence Interval = [1.59–2.27]). While there was (ii) no difference between monozygotic and dizygotic twins regarding prevalence of left- (Odds Ratio = 0.98, 95% Confidence Interval = [0.89, 1.07]), mixed- (Odds Ratio = 0.96, 95% Confidence Interval = [0.46, 1.99]), or non-right-handedness (Odds Ratio = 1.01, 95% Confidence Interval = [0.91, 1.12]), we found that (iii) handedness concordance was elevated among monozygotic compared to dizygotic twin pairs (Odds Ratio = 1.11, 95% Confidence Interval = [1.06, 1.18]). By means of moderator analyses, we did not find evidence for effects of potentially confounding variables.

Conclusion: We provide the largest and most comprehensive meta-analysis on handedness in twins. Although a raw, unadjusted analysis found a higher prevalence of left- and non-right-, but not mixed-handedness among twins compared to singletons, left-handedness was substantially more prevalent in earlier than in more recent studies. The single large, recent study which included birth weight, Apgar score and gestational age as covariates found no twin-singleton difference in handedness rate, but these covariates could not be included in the present meta-analysis. Together, the secular shift and the influence of covariates probably make it unsafe to conclude that twinning has a genuine relationship to handedness.

Discussion

In three sets of meta-analyses, we examined the influence of twin status and twin zygosity on handedness prevalence and handedness concordance. Our first set of meta-analyses confirmed that in line with Sicotte et al. [10], left-handedness (OR = 1.40, Fig. 3) and non-right-handedness (OR = 1.36, Fig. 5) occur more often among twins than among singletons. Moderator analyses found elevated levels of non-right-handedness among twins to be independent of all variables tested with respect to a potential moderating effect. However, we found that more recent studies reported smaller differences in prevalence of left-handedness between twins and singletons (Fig. 6). To test whether there is a higher left-handedness prevalence in twins compared to singletons in more recent studies at all, we estimated twin-to-singleton ORs for left-handedness for studies published pre and post 1975 separately. With a pre-1975 OR of 1.90 (95% CI = [1.59, 2.27]) and a post-1975 OR of 1.30 (95% CI = [1.17, 1.45]), ORs for more recent studies were smaller, but still indicated a significant twin effect on left-handedness.

Overall, the decrease in twin-to-singleton ORs might either be explained by a decrease in left-handedness in twins or an increase of left-handedness in singletons, or both. As already mentioned, complications occur more often in the course of multiple births [11,12,13], which might contribute to the development of atypical handedness [10]. However, most individual studies included in our meta-analysis did not provide information on pre- or perinatal conditions, so we could not test for a moderating effect of these conditions on the twin-to-singleton OR. Along these lines, future research might have a closer look on the relation between birth complications and handedness.

Assuming that higher proportions of left-handedness among twins might be the by-product of birth complications, a decrease in atypical handedness in twins must be assigned to a decrease in the occurrence of these complications. In fact, it is well conceivable that medical progress over the last decades, that is clearly detectable, e.g. in the United States [92, 93], may have helped to equalize the risks associated with multiple and single births. Such assumptions are supported by a study by Heikkilä et al. [77] who showed differences in left-handedness in twins and singletons to disappear when controlling for birth weight, Apgar score, and gestational age. We therefore tested whether there is evidence for a decrease in left-handedness prevalence in twins (Fig. 6b) by running meta-analyses on left-handedness prevalence in twins and singletons separately while including publication year as a moderator variable. However, while there was no evidence for an effect of publication year on left-handedness prevalence in twins, there seemed to be a trend towards an increase of left-handedness prevalence in singletons (Fig. 6c).

The overall prevalence of atypical handedness in our study was lower than expected. We found 9.13% of twins and 6.97% of singletons to be left-handed (Table 1), while Papadatou-Pastou et al. [3] reported a figure of 10.6% (95% CI 9.71%, 11.50%) for the general population. The low values in our study might be the result of a general effect of publication year in singletons, given that the prevalence of left-handedness has been shown to be higher in younger than in older cohorts [25, 94, 95]. The social stigma associated with left-handedness in the last century [96] may have driven left-handers to conceal their preference in self-reports [97] and to retrain to use their right hand [25, 98]. Most of the studies included in our meta-analysis were published in the previous century and their participants could have been subjected to environmental pressures against left-handedness, leading to underestimation of the true population prevalence of left-handedness. Similarly, we found low overall prevalence of mixed-handedness (3.39% in twins and 2.67% in singletons, Table 1), whereas Papadatou-Pastou et al. [3] gave a point estimate of 9.3% for the general population. This might also be due to an effect of publication year. Moreover, three of five studies that provided data for mixed-handedness classified handedness as writing hand so that data extracted from these studies most likely reflect not mixed-handedness, but ambidexterity, which is much rarer [99].

Our second set of meta-analyses found no difference in the prevalence of atypical handedness between MZ and DZ twins (left-handedness OR = 0.98, mixed-handedness OR = 0.96, non-right-handedness OR = 1.01, Table 3). This result is consistent with the meta-analysis by Sicotte et al. [10] who interpreted this null-effect as indication against mirror imaging theories designed to explain heightened frequencies of left-handers and frequent handedness discordance among MZ twins [100,101,102]. Indeed, it weakens the hypothesis suggesting that the monozygotic twinning process is responsible for atypical handedness [10]. Moreover, it indicates that the overall heightened frequencies of left- and non-right-handers among twins are independent of the twins’ zygosity. A moderator analysis showed that this effect was not influenced by the method used to determine the twins’ zygosity, thus refuting the idea that the result was affected by the accuracy with which twins were classified as monozygotic or dizygotic. All in all, revealing comparable prevalence of atypical handedness for MZ and DZ twins cannot enrichen knowledge about genetic contribution to handedness per se. As already recognized by Sicotte et al. [10], to do so, it is crucial to look at pairwise handedness concordance or discordance of MZ and DZ twin pairs.

Our third set of meta-analyses found a small yet significant effect (OR = 1.11, Fig. 7) for higher handedness concordance among MZ (80.49%) as compared to DZ (79.27%) twins, consistent with the meta-analysis by Sicotte et al. [10]. Even though other publications have demonstrated the occurrence of handedness discordance among MZ twin pairs [100, 101, 103, 104], it was estimated to concern a minority of 20–25% of cases [2]. Stronger phenotypic variation among DZ compared to MZ pairs indicates a certain genetic foundation of that phenotype [2, 26]. Therefore, our results confirm handedness to rely on genetic factors to some extent [10] and are consistent with heritability estimates of 0.24–0.26 [31,32,33]. A moderator analysis suggested that the frequencies of handedness concordance did not differ between studies included in the meta-analysis by Sicotte et al. [10], studies explicitly excluded from Sicotte et al. [10], and more recent studies.

To allow future meta-analyses to perform comparisons on handedness prevalence in twins more specifically (e.g., handedness in male vs. female twins, or handedness in same sex pairs vs. opposite sex pairs), it is desirable that researchers report results broken down for parameters like zygosity, sex, and consider data on birth complications. As this might be beyond the scope of individual papers, we encourage authors to provide open raw data in publicly accessible repositories such as the osf.io.

The present study is not without limitations. We did not investigate relative hand skill but were restricted to hand preference. Measuring hand preference is far more established as compared to assessing relative hand skill, as it is easier and more convenient [105]. Most of the studies included in our meta-analysis only provided information on hand preference, not allowing for an additional analysis for hand skill. Moreover, hand preference and hand skill correlate to some extent [106,107,108], and the distribution of handedness categories overlaps for preference- and skill-related criterions in 90% of the cases [109].

Similarly, our study only dealt with handedness direction in terms of categorial handedness classification which does not take into account the fact that individual handedness can further be defined regarding its strength or its degree. Along these lines, other approaches consider handedness as a continuum, extending the question to how strong or how consistently one hand is preferred, used, or skilled over the other. Indeed, several findings obtained within laterality research on associations between handedness and structural brain lateralization [110] or cognitive performance [111, 112] as well as concerning the genetic foundation of handedness [113, 114] are linked to strength but not direction of handedness. However, since most studies included in the present meta-analyses did not assess handedness in a continuous manner, we were unable to account for handedness strength. Therefore, it falls to future studies to extend their assessment repertoire by measures of handedness strength.

From a methodological point of view, it is further crucial to mention that overall, our moderator analyses are low in power due to the investigated study sample sizes. Of note, in some cases, moderator levels included only three data points calling for an interpretation of these findings with caution.

Meta-analysis: People do not drink alcohol to drown their sorrows, but to indulge in their joys

Dora, Jonas, Marilyn Piccirillo, Katherine T. Foster, Kelly Arbeau, Stephen Armeli, Marc Auriacombe, Bruce D. Bartholow, et al. 2022. “The Daily Association Between Affect and Alcohol Use: A Meta-analysis of Individual Participant Data.” PsyArXiv. February 1. psyarxiv.com/xevct

Abstract: Influential psychological theories hypothesize that people consume alcohol in response to the experience of both negative and positive emotions. Despite two decades of daily diary and ecological momentary assessment research, it remains unclear whether people consume more alcohol on days they experience higher negative and positive affect in everyday life. In this preregistered meta-analysis, we synthesized the evidence for these daily associations between affect and alcohol use. We included individual participant data from 69 studies (N = 12,394), which used daily and momentary surveys to assess affect and the number of alcoholic drinks consumed. Results indicate that people do not drink more often on days they experience high negative affect, but are more likely to drink and drink heavily on days high in positive affect. People self-reporting a motivational tendency to drink-to-cope and drink-to-enhance were estimated to consume more alcohol, but not to consume more alcohol on days they experience higher negative and positive affect. Results were robust across different operationalizations of affect, study designs, study populations, and individual characteristics. Based on our findings, we collectively propose an agenda for future research to explore open questions surrounding affect and alcohol use.

Age, gender, geographical region, belonging to the host country, religious fractionalization, & stereotypic gender roles (proxied by labor force participation rate of women in the athlete’s country) are prominent predictors of crying in the Olympics

Golden tears: A cross-country study of crying in the Olympics. Alex Krumer, Andrew Musau. January 2022. https://www.researchgate.net/publication/358233754_Golden_tears_A_cross-country_study_of_crying_in_the_Olympics

Description: Previous psychological studies on emotional crying have overwhelmingly relied on self-reported data from individuals’ recollections of their own experiences. Apart from the bias that arises from faulty recollection, there is no incentive for an individual to truthfully reveal his or her own experiences in such surveys. In this paper, we address the methodological limitations associated with self-reporting and non-sufficient emotional elicitors, by exploring data on gold medalists of all 450 individual events at the 2012 and 2016 Summer Olympic Games at the end of the medalists’ respective competitions and during the medal ceremonies. We find that age, gender, geographical region, belonging to the host country, religious fractionalization, and stereotypic gender roles (proxied by labor force participation rate of women in the athlete’s home country) are likely to be prominent predictors of crying. Thus, our results suggest that emotional crying is not only a biological feature, but also a cultural phenomenon.

Social acceptance & social anxiety, embarrassment, jealousy, hurt feelings, guilt, & lowered self-esteem: We may do distance ourselves from other people, aggress rejecters, or engage in symbolic efforts to increase subjective acceptance

The relentless pursuit of acceptance and belonging. Mark R. Keary, Shira Gabriel. Advances in Motivation Science, January 31 2022. https://doi.org/10.1016/bs.adms.2021.12.001

Abstract: A great deal of human behavior is motivated by the desire for acceptance and belonging, and a high proportion of people's emotional reactions stems from concerns with actual or potential social rejection. The pervasive quest for acceptance can be seen in the attention and effort people devote to their physical appearance, their efforts to be liked, achievement-related behaviors, conformity, accumulating resources that others need, and generally being the sort of person with whom others want to have social connections. Depending on the context, concerns with social acceptance are typically accompanied by emotions such as social anxiety, embarrassment, jealousy, hurt feelings, and guilt, as well as lowered self-esteem. In addition, people who feel inadequately valued and accepted may behave in ways to increase acceptance, aggress against those who rejected them, distance themselves from other people, and/or engage in symbolic efforts to increase their subjective sense of being accepted. Concerns with acceptance and belonging exert a pervasive, ongoing effect on human thought, behavior, and emotion.

Keywords: BelongingAcceptanceRejectionExclusionOstracismRelational value

COVID-19 state anxiety is linked to everyday cognition and slower processing speed in women, but not men

COVID-19-Related Anxiety and Cognition in Middle-Aged and Older Adults: Examining Sex as a Moderator. Ashley F. Curtis et al. Psychological Reports, January 31, 2022. https://doi.org/10.1177/00332941211064820

Abstract: Aging populations experience disproportionate risk for cognitive decline, which may be exacerbated by coronavirus (COVID-19) illness, particularly among women. This study tested sex as a moderator of associations between COVID-19 state anxiety and cognition in middle-aged/older adults. Adults aged 50+ (N = 275; 151 men/124 women) completed the Coronavirus Anxiety Scale and Cognitive Failures Questionnaire online from remote locations in July/August 2020. A subset of participants (n = 62) completed an objective cognitive task (Stroop). Multiple regressions determined whether sex moderated associations between COVID-19 anxiety and cognitive outcomes. Sex was a significant moderator, such that for women (not men), greater COVID-19 anxiety was associated with more memory failures and blunders (subjective measures) and worse processing speed (objective measure). COVID-19 state anxiety is linked to everyday cognition and processing speed in women, but not men. Consistency across subjective and objective measures promotes the need for sex-specific understanding of the pandemic’s behavioral and cognitive effects in mid-to-late life.

Keywords: Cognition, coronavirus, anxiety, sex differences, middle-aged adults, older adults

37% of the participants contacted other persons because they dreamed about them; dream recall frequency, attitude towards dreaming, younger age, and female gender was associated with contacting the person(s) dreamed of

The Frequency of Contacting Persons you Dreamed About: A Social Aspect of Dreaming. Michael Schredl, Anja S. Göritz. Imagination, Cognition and Personality, January 31, 2022. https://doi.org/10.1177/02762366221077631

Abstract: Although dreams are very private, dreaming has also social components, i.e., dreams are shared quite often. We studied the frequency of how often the dreamer deliberately contacted another person because s/he dreamed about this person, as this might intensify the waking-life bonds with this person. Overall, 2929 participants completed the dream survey, and a subsample also completed a Big Five Personality inventory. The findings indicate that 37% of the participants contacted other persons because they dreamed about them. Dream recall frequency, attitude towards dreaming, younger age, and female gender was associated with contacting the person(s) dreamed of. Moreover, extraversion was also related to the frequency of contacting the person(s) dreamed of – similar to the relationship found for dream sharing frequency and extraversion. However, the association with low conscientiousness is a new finding. It would be very interesting to test whether this social behavior (contacting another person) motivated by dreams strengthens the social bonds between the dreamer and the contacted person(s) and thereby provide support for the Social Simulation Theory.

Keywords: social aspects of dreaming, dream recall frequency, attitude towards dreaming, extraversion, conscientiousness