No mechanism known to explain positive observed effect of 2.45 GHz Wi‐Fi exposure on sleep‐dependent memory consolidation

Effects of 2.45 GHz Wi‐Fi exposure on sleep‐dependent memory consolidation. Ana Bueno‐Lopez  Torsten Eggert  Hans Dorn  Gernot Schmid  Rene Hirtl  Heidi Danker‐Hopfe. Journal of Sleep Research, November 9 2020. https://doi.org/10.1111/jsr.13224

Rolf Degen's take: https://twitter.com/DegenRolf/status/1326395159362342913

Abstract: Studies have reported that exposure to radiofrequency electromagnetic fields (RF‐EMF) emitted by mobile telephony might affect specific sleep features. Possible effects of RF‐EMF emitted by Wi‐Fi networks on sleep‐dependent memory consolidation processes have not been investigated so far. The present study explored the impact of an all‐night Wi‐Fi (2.45 GHz) exposure on sleep‐dependent memory consolidation and its associated physiological correlates. Thirty young males (mean ± standard deviation [SD]: 24.1 ± 2.9 years) participated in this double‐blind, randomized, sham‐controlled crossover study. Participants spent five nights in the laboratory. The first night was an adaptation/screening night. The second and fourth nights were baseline nights, each followed consecutively by an experimental night with either Wi‐Fi (maximum: psSAR10g = <25 mW/kg; 6 min average: <6.4 mW/kg) or sham exposure. Declarative, emotional and procedural memory performances were measured using a word pair, a sequential finger tapping and a face recognition task, respectively. Furthermore, learning‐associated brain activity parameters (power spectra for slow oscillations and in the spindle frequency range) were analysed. Although emotional and procedural memory were not affected by RF‐EMF exposure, overnight improvement in the declarative task was significantly better in the Wi‐Fi condition. However, none of the post‐learning sleep‐specific parameters was affected by exposure. Thus, the significant effect of Wi‐Fi exposure on declarative memory observed at the behavioural level was not supported by results at the physiological level. Due to these inconsistencies, this result could also be a random finding.

4 DISCUSSION

The present provocation study, which can only address acute effects, analysed whether a Wi‐Fi exposure during TIB (8 h) might affect sleep‐dependent memory consolidation processes (declarative, procedural and emotional memory) and their learning‐associated brain activity during sleep in young healthy male volunteers.

4.1 Sleep‐dependent memory consolidation: Behavioural level

Results show that although Wi‐Fi did not affect retention in the procedural and emotional memory tasks, the data reveal that retention in the declarative memory was increased after Wi‐Fi as compared to sham exposure.

In the WPT, overnight performance gain was higher after Wi‐Fi exposure compared to sham (see Figure 3a.i), with an effect size of 0.40. According to Cohen (1988) this is a small effect, which, however, has a large uncertainty (95% CI [0.11; 0.70]). This observed difference in overnight retention of correctly recalled word pairs between sham and Wi‐Fi exposure conditions represented moderate evidence for the alternative hypothesis when evaluated based on the corresponding Bayes factor (BF01 = 0.254) (see Table 2). However, the interaction of several factors needs to be taken into account in order to interpret this result accurately. Small differences in the number of correctly recalled word pairs during immediate recall might have affected performance gains in the WPT. That is, the number of correctly recalled word pairs in the evening was slightly, but not significantly, higher in the sham nights as compared to Wi‐Fi, whereas the opposite was observed in the morning (see Table 2). The lower “reference level” in the evening preceding the Wi‐Fi condition might explain why overnight change was significantly higher under Wi‐Fi compared to sham. On the other hand, as both versions of the WPT had the same level of difficulty, it is unlikely that encoding difficulties could explain this finding. Regardless of the exposure condition, the performance on the evening of the two experimental nights did not differ, which supports the absence of a learning effect between experimental nights (see Table S5). Moreover, the data did not reflect the presence of floor or ceiling effects.

Wi‐Fi exposure did not affect performance in the FRT. Overnight retention was similar between Wi‐Fi and sham exposure. Bayes factors showed that overnight retention in all categories presented moderate evidence for the absence of a decline or improvement after exposure (all faces: BF01 = 3.931; neutral faces: BF01 = 4.538; positive faces: BF01 = 3.155; negative faces: BF01 = 5.527) with effect sizes (Cohen's d) that vary from no (negative faces) to small effects (all, neutral and positive faces; see Table 2). Thus, recognition memory in the emotional task did not differ between exposure conditions.

Performance improvements in the SFTT after sleep were not affected by Wi‐Fi exposure. The results for the overnight retention in this memory task did not differ between exposure conditions. Moreover, retention in this task showed moderate evidence for the null hypothesis (BF01 = 4.539), which is supported by a small effect size (see Table 2). In contrast, Lustenberger et al. (2013) reported a reduction of the performance improvement, measured as the variance of the reaction time, in a similar SFTT under RF‐EMF exposure compared to sham (with an effect size of |d| = 0.57 representing a medium effect; effect size calculated from data presented in Lustenberger et al., 2013). This effect could not be confirmed by our results. The variance in reaction time performance in the present study did not differ significantly between the exposure conditions, the effect size indicates no effect (|d| = 0.13) and the Bayes factor indicates moderate evidence for the null hypotheses (BF01 = 6.355) (see Table S4, and Figure S2). However, beside different signal characteristics, Lustenberger et al. (2013) used substantially higher intensities of RF‐EMF exposure, whereas in the present study the applied RF‐EMF intensities represent realistic worst‐case exposure from real Wi‐Fi installations.

Irrespective of exposure, the present results confirmed the beneficial role of sleep for memory consolidation. Performance in the three memory tasks improved after a night of sleep, reflecting small (FRT, 0.014) to medium effect sizes (WPT, 0.069; SFTT, 0.116) as indicated by generalized η2 values. Sleep‐dependent improvements in memory consolidation have been extensively discussed using different declarative and non‐declarative memory tasks showing that post‐sleep memory retention is better than retention after a wake period (Rasch & Born, 2013). This sleep‐specific beneficial effect is assumed to be reflected in the present results. In particular, in the WPT, declarative memory enhancements after a night of sleep under both experimental conditions are in line with multiple other studies (for reviews, see Diekelmann et al., 2009; Rasch & Born, 2013). Regarding the FRT, recognition memory performance for all faces, regardless of their emotional valence, improved after a night of sleep, which is in agreement with previous findings (Solomonova et al., 2017; Wagner et al., 2007). Additionally, memory performance was better after sleep for neutral and positive facial expressions. These findings are consistent with the results of a recent meta‐analysis (Schäfer et al., 2020), which revealed an enhancement of recognition memory for both emotional and neutral stimuli. In contrast, recognition for negative stimuli did not improve after sleep in the present study. In this respect, only the neutral faces were recognized during the evening recall phase more effectively on the second experimental night when compared with the first night, regardless of the exposure condition (see Table S5). Finally, results of the SFTT are in line with the evidence of the contribution of sleep to procedural memory consolidation (for review, see King et al., 2017).

4.2 Sleep‐specific features related to memory consolidation: Physiological level

There is compelling evidence that depending on the type of memory, certain sleep stages and sleep EEG characteristics are related to the previously mentioned memory consolidation processes. With regard to the macrostructure of sleep, overnight improvements in declarative memory have been related to slow‐wave sleep (N3) (e.g., Diekelmann et al., 2012), whereas overnight improvements in procedural memory have been proposed to be related to time spent in stage N2 sleep (e.g., Walker et al., 2002). Additionally, REM sleep has been associated with both procedural and declarative memory consolidation (Fogel et al., 2007). Finally, the consolidation of emotional memory has been proposed to be dependent on both REM sleep and NREM sleep (Tempesta et al., 2018).

The present analysis revealed that Wi‐Fi exposure had no effect on time spent in sleep stages N2, N3 (slow‐wave sleep), NREM or REM sleep. Bayes factors for N2 and N3 sleep supported this interpretation by providing moderate evidence for the absence of an exposure effect on these two sleep stages (N2, BF01 = 6.672; N3, BF01 = 5.379). The corresponding Cohens' d values indicated also no effect. However, Bayes factors for NREM and REM sleep indicated only anecdotal evidence for the H0 (NREM, BF01 = 2.414; REM, BF01 = 2.266), with Cohens' d values representing small effects (see Table 3). In other words, these results pointed out that N2 and N3 sleep were rather unlikely to be affected by Wi‐Fi exposure, but that an exposure effect on NREM and REM sleep cannot be excluded. It could be speculated that the evaluation of these two effects, whether they are supportive of the null or alternative hypothesis, would have been more convincing if the sample size had been larger. Then, if this supported the tendency observed in NREM sleep at the descriptive level under Wi‐Fi exposure compared to sham (see Table 3), this possible change in NREM could explain at least partially the improvement of declarative memory consolidation.

The literature shows that RF‐EMF effects on sleep architecture are quite heterogeneous. Although some studies found effects in the discussed sleep parameters, others did not (for detailed overview, see Danker‐Hopfe et al., 2016). Therefore, the present results can be assigned to the group of studies that reported null findings with regard to effects of exposure on sleep macrostructure. The same applies to the study by Danker‐Hopfe et al. (2020), which examined the impact of Wi‐Fi exposure on a large number of objective sleep parameters in addition to some subjective sleep variables. This previous study, however, considered sleep data from all 34 recruited participants and disregarded deliberately some of the sleep‐specific variables that are thought to be associated with memory consolidation processes. Thus, the present study fills this gap and complements this previous publication, but with results restricted to a subsample of 30 subjects for whom behavioural data were available.

With regard to sleep microstructure, sleep spindle frequency ranges, as well as slow‐wave activity (0.1–3.5 Hz), have been associated with both declarative and procedural memory improvements (Fogel et al., 2007; Holz et al., 2012). However, other studies did not find a clear association between performance improvements and related sleep stages or EEG power in declarative (Gais et al., 2002) or procedural memory (Rångtell et al., 2017). Sleep spindle density has been proposed to be involved in declarative (e.g., Gais et al., 2002) and in procedural (e.g., Barakat et al., 2011) memory consolidation. Additionally, emotional memory has been positively correlated with fast spindle densities (13–16 Hz) and negatively with slow spindle (10–13 Hz) densities (Solomonova et al., 2017).

The present results did not reveal any Wi‐Fi exposure effect on the EEG power in the ranges of slow oscillations (0.5–0.1 Hz) and narrow (12–14 Hz) and wide (12–16 Hz) sleep spindles. Nor was the sleep spindle density in stages N2 and N3 sleep affected by exposure (see Table 4). This is supported by Cohen's d values, which indicate small or no effects (see Table S2). Bayes factors revealed moderate evidence for the absence of a Wi‐Fi effect on the narrow sleep spindle frequency range at all regions in N2 and N3. Similarly, Bayes factors indicated moderate evidence for the absence of a Wi‐Fi effect on the EEG power in the wide spindle frequency range and in the range of slow oscillations in all cortical regions in both sleep stages, except for the occipital region in N2 and N3. In these cases, Bayes factors revealed only anecdotal evidence for the absence of Wi‐Fi effects. As mentioned above, a larger sample size could have provided stronger evidence for the presence or absence of the reduced EEG power under Wi‐Fi exposure that can be observed at the descriptive level (see Table S2). Furthermore, Bayes factors revealed moderate evidence for an absence of an exposure effect on sleep spindle densities in both sleep stages, with Cohen's d values indicating no effects (see Table S3).

In this respect, Lustenberger et al. (2013) reported that pulsed RF‐EMF induced an increase of slow‐wave activity at the end of the sleep period, whereas spindle activity remained unchanged and sleep‐dependent procedural memory gains were downscaled. Similarly, other RF‐EMF studies did not report effects on the EEG in the spindle frequency range (Fritzer et al., 2007; Hinrichs et al., 2005; Nakatani‐Enomoto et al., 2013; Wagner et al., 1998, 2000) or for spindle density (Lustenberger et al., 2015), in line with the present results. However, as pointed out previously, RF‐EMF effects on the sleep EEG power show mixed results.

In summary, the results at the physiological level did not reveal an impact of Wi‐Fi exposure on any of the sleep parameters that are generally associated with sleep‐dependent memory consolidation processing, such as NREM sleep, specifically slow‐wave sleep, as well as EEG power values in the SO and spindle frequency ranges, and sleep spindle densities. Accordingly, the positive effects that Wi‐Fi exposure had on memory retention in the declarative task were not supported by physiological changes associated with memory consolidation processes during sleep. Thus, the present behavioural and neurophysiological findings did not provide evidence that night‐time Wi‐Fi exposure affects sleep‐dependent memory consolidation, so the positive exposure effect on declarative memory should be classified as inconclusive.

Self‐directed sexist humor was seen as more affiliative (only women), less aggressive, & more self‐defeating than other‐directed sexist humor; women romantically preferred men who used self‐ rather than other‐directed sexist humor

Is it sexy to be sexist? How stereotyped humor affects romantic attraction. Diana E. Betz  Theresa E. DiDonato. Personal Relationships, November 9 2020. https://doi.org/10.1111/pere.12346

Abstract: Sexist humor is a common form of disparagement humor that is nonetheless understudied in romantic attraction contexts. Three experiments investigated how sexist humor is perceived and received during relationship initiation. In Study 1 (n = 262) participants rated self‐directed sexist humor as more affiliative (only women), less aggressive, and more self‐defeating than other‐directed sexist humor. Study 2 (n = 209) replicated these findings and found that women romantically preferred men who used self‐ rather than other‐directed sexist humor, an effect mediated by perceived warmth. Self‐directed sexist humor's attractiveness advantage persisted in Study 3 (n = 667), which also included manipulations of self‐disparaging, group‐disparaging, and benign humor. Results suggest a romantic cost for men telling sexist jokes that disparage women.

Social Media and Well-Being: Small negative effects on average, with both positive & negative sides... Alarm seems exaggerated by the media due to our focus on the negative

Social Media and Well-Being: Pitfalls, Progress, and Next Steps. Ethan Kross et al. Trends in Cognitive Sciences, November 10 2020. https://doi.org/10.1016/j.tics.2020.10.005

Rolf Degen's take: https://twitter.com/DegenRolf/status/1326180998074273797

Highlights

-  Social media has revolutionized how humans interact, providing them with unprecedented opportunities to satisfy their social needs.

-  An explosion of research has examined whether social media impacts well-being. First- and second-generation studies examining this issue yielded inconsistent results.

-  An emerging set of third-generation experiments has begun to reveal small but significant negative effects of overall social media use on well-being.

-  The results of these experiments mask the complexities characterizing the relationship between social media and well-being. Whether it enhances or diminishes well-being depends on how and why people use it, as well as who uses it.

-  People use social media for different reasons (e.g., to manage impressions, to share emotions), which influence how it impacts their own and other people’s well-being.

Abstract: Within a relatively short time span, social media have transformed the way humans interact, leading many to wonder what, if any, implications this interactive revolution has had for people’s emotional lives. Over the past 15 years, an explosion of research has examined this issue, generating countless studies and heated debate. Although early research generated inconclusive findings, several experiments have revealed small negative effects of social media use on well-being. These results mask, however, a deeper set of complexities. Accumulating evidence indicates that social media can enhance or diminish well-being depending on how people use them. Future research is needed to model these complexities using stronger methods to advance knowledge in this domain.

Keywords: social mediaFacebookwell-beingonline social networksemotionlife satisfaction

Moving Forward

We have drawn multiple parallels between the printing press and social media in this review, but there is one notable difference. Whereas the printing press took decades to revolutionize the way society functioned, social media have had a transformational impact in a tiny window of time. Nevertheless, scientists have been remarkably nimble in their ability to reroute their research programs to respond to the challenge of making sense of how this technology impacts people’s emotional lives. Indeed, we view the past 15 years of research on social media and well-being as a testament to scientists doing what they do best: focusing on important phenomena, critically evaluating current knowledge in light of new results, and bringing to bear increasingly sophisticated methods and conceptual frameworks to generate novel solutions that have important basic science and practical implications. But where does all of this work leave us in terms of the question on so many people’s minds: how do social media influence well-being?

Converging reviews of the literature suggest that a small but significant negative relationship characterizes the effect of social media on well-being (Box 3). If this is all that one cares about, that is the bird’s eye view. It would be a mistake, however, to conclude from these findings that social media have little potential to influence people’s emotional lives. Our survey suggests that the situation concerning social media’s impact on well-being is considerably more nuanced than aggregate usage studies suggest. The effects of social media on well-being are not uniform. Social media present people with a new ecosystem for engaging in social interactions, and converging evidence indicates that how this ecosystem affects our well-being, and the well-being of others, depends on how we navigate it.

Box 3

Beyond ‘Active’ versus ‘Passive’ Usage

In an attempt to integrate research showing that different ways of using social media differentially impact well-being, several groups have distinguished between two general categories of social media usage: ‘active’ and ‘passive’ social media usage. According to this framework, the passive consumption of information on social media undermines well-being by increasing upward social comparisons. Conversely, the active use of social media to exchange information and to connect with others enhances well-being by enhancing social capital and support.

This framework has proved useful in pushing the field to think more mechanistically and has revealed differential negative effects of passive (vs active) use (Box 2). Nevertheless, further refinement of this framework is necessary; current research suggests that it is too coarse. As we discuss in the main text, although passively viewing other people’s social media profiles reliably undermines well-being, passively viewing one’s own profile has the opposite effect. Likewise, although actively using social media to garner support improves well-being, actively using it to cyberbully or spread moral outrage undermines well-being for others. Thus, a key challenge is to move beyond this nominal distinction to examine subtypes of active and passive social media use. In particular, two questions are pressing.

First, we need to understand how different motivations for using social media interact to influence well-being. Extant research has primarily focused on how different social media motivations operate in isolation. However, human behavior is multiply determined; multiple goals drive people’s behavior, which are activated to various degrees depending on individual differences and the circumstances people find themselves in [113,114]. And in some cases, motivations conflict. For example, a person may be driven to abstain from viewing others’ profiles to avoid feeling envy, but simultaneously motivated to share their emotions with others. Which of these motivations is stronger may influence whether and how people interact with social media and the implications that doing so has for their well-being.

Second, research is needed to examine whether people are aware of the implications that their social media behavior has for themselves and others. Our review suggests that an asymmetry characterizes how several social media behaviors impact the self versus others. For example, curating one’s profile improves how one feels, but promotes envy among others; cyberbullying disproportionately impacts the targets (vs perpetrators) of such behavior. Whether people are aware of these asymmetries is unknown, as are the consequences of informing them about them for regulating their social media behavior.

If social media have both positive and negative implications for well-being, one question concerns why the dominant narrative in the media has disproportionately focused on its dire consequences [6]. The newsworthiness of such headlines is likely to play some role in explaining this phenomenon, but we suspect it is not the only factor. In this vein, it is worth highlighting the fact that one of psychology’s most foundational findings concerns our tendency to overweight negative (vs positive) information [72,73]. Thus, it is possible that people form generalizations about social media’s overall well-being impact based on the negative effects they have in some situations (e.g., upward social comparisons, cyberbullying). A key challenge moving forward is to identify how to disseminate information about social media’s positive and negative implications without having the latter obscure the former.

From a basic science perspective, future research is needed to move beyond asking broad questions about the overall effects of social media on well-being (see Outstanding Questions). Rather, the strategy now should be to study the different psychological processes that explain how and why social media impact well-being differently, whether different social media behaviors have downstream effects that extend beyond well-being (e.g., to impact family and school life), and why these effects may vary for different people in different cultures guided by distinct social norms. Although we focused on two candidate processes in this review that have been the focus of extensive research, many other processes are waiting to be examined. Work should continue to profile how target processes operate in isolation but also explore how they interact (Box 3).

Studies that seek to address the latter issue should also consider the unique information-processing dynamics that may underlie different types of social media behaviors. Managing one’s online persona would seem, for example, to be a reflective act that requires time and deliberation to implement. Sharing emotions with others, by contrast, may be a more reflexively driven behavior. Understanding the degree to which different social media behaviors are reflexively versus reflectively driven has the potential to both illuminate the processes that underlie them and inform the development of interventions designed to enhance social media’s impact on well-being [102].

Focusing more on psychological processes also has the potential to provide insight into the question of how different social media platforms uniquely impact well-being. By focusing on the processes that different platforms activate, as opposed to simply comparing Platform A (e.g., Facebook) versus Platform B (e.g., Instagram), we can move beyond the nominal distinctions that distinguish platforms, to the more meaningful psychological variables that influence users’ experience (Figure 1).

This issue is also relevant to the emerging experimental literature examining the impact of manipulating aggregate social media use on well-being. Extant research manipulates social media usage in a variety of ways. Some work contrasts experimentally induced abstention against regular usage (e.g., [33]) while others contrast induced usage against an active or non-active control (e.g., [32]), and there is further heterogeneity within these broad approaches (e.g., in the length of abstention/usage, simple abstention vs deactivation of accounts). Each of these different manipulations may activate a different set of underlying processes that have implications for people’s well-being.

Studying psychological processes requires, however, that we utilize strong methods. The field’s overreliance on cross-sectional designs is a major weakness [35,36], yet cross-sectional research continues to proliferate. We urge researchers interested in exploring the social media–well-being relationship to incorporate experimental and longitudinal designs into their work to strengthen their ability to draw inferences about causality.

More work is also needed to validate the methodologies we use to study the impact of social media on well-being. We have already discussed the validity concerns associated with commonly used self-report Facebook usage variables. However, similar issues apply to other measures used in this area. For example, one prominent study counted the number of emotion words contained in people’s Facebook posts to draw inferences about how they felt although no validation data supported the use of such methods to track people’s emotions on social media [103]. As later research pointed out, counting emotion words does not track how people feel on Facebook [104]. The take-home point is simple: psychometrically sound measures are not a luxury: they are instrumental for valid inferences.

From a translational standpoint, there is a need to identify science-based interventions that enhance the positive and minimize the negative consequences of social media. There are at least three paths to studying these interventions (Figure 2). One involves directing people to use social media in particular ways, and then gauging the implications of such person-focused interventions. Much of the existing experimental work in this area takes this form. A second path involves examining how modifying the social media platforms that people use (with their informed consent) impacts the way they use them and how they affect well-being. For example, a platform could be augmented to promote the sharing of information that research suggests should enhance well-being. Finally, a third method involves a combination of the previous two approaches; that is, simultaneously educating people about how to navigate social media optimally and tweaking social media platforms to maximize their positive impact.

[Figure 2. Social Media Intervention Research.]

At least three pathways exist for process-focused social media intervention research. Person-centered interventions focus on changing how people use social media to enhance well-being. Potential ways of communicating this information include instructing individuals directly, relaying information through parents, teachers, or supervisors, and the creation of institutional policies. Platform-centered interventions involve changing the way that social media platforms function (with user consent) to enhance their likelihood of promoting well-being. Finally, the person + platform intervention pathway involves the examination of the effects of both kinds of intervention simultaneously.

Concluding Remarks

Social media, like the printing press, represent a kind of disruptive technology that appears once in a generation. Over the past 15 years science has done an admirable job advancing our understanding of the impact these media have on our well-being, but the work is by no means complete. Numerous questions remain. Given the energy and enthusiasm characterizing work in this area, and the enormous level of talent working on solving these questions, we suspect that the next 15 years will be ripe with discoveries that advance our understanding of how this ubiquitous technology influences our emotional lives.

Outstanding Questions

Can we find a common lexicon to conceptualize the social media landscape? Addressing this issue is vital to solving social media’s jingle-jangle problem (Box 1).

Can we develop theory-driven frameworks to identify candidate processes that explain how social media impacts well-being and generate predictions about how they operate in isolation and interactively? Can such frameworks be used to distinguish between different social media platforms?

Can we make further distinctions within active and passive social media usage? Do different active and passive behaviors relate to different psychological processes? Are some behaviors more impulsive versus deliberate? How might these different behaviors impact well-being?

Do asymmetries in the way certain social media behaviors impact the self versus others help to explain why some harmful practices persist? If so, how can such information be utilized to inform interventions?

Can we systematize the way we perform experiments on social media? Some experiments direct people to abstain from using social media while others direct them to use it more compared with baseline. Heterogeneity also characterizes the time course of different manipulations, the measures used to document their effects, and the frequency of their administration. All of these factors could differentially impact study results depending on the nature of the process being manipulated.

How can we balance the need to perform studies quickly on an evolving technology without compromising the need to use valid measures and methods?

Can we design person- and platform-centered interventions that amplify the positive and diminish the negative implications of social media use on well-being?

How can we disseminate information about social media’s positive and negative impacts without having the latter obscure the former, given the documented tendency for people to overweight negative (vs positive) information?

Women’s Hunting in Two Contemporary Forager-Horticulturalist Societies

“Hunting Otherwise.” Women’s Hunting in Two Contemporary Forager-Horticulturalist Societies. Victoria Reyes-García, Isabel Díaz-Reviriego, Romain Duda, Álvaro Fernández-Llamazares & Sandrine Gallois. Human Nature volume 31, pages203–221. Sep 11 2020. https://link.springer.com/article/10.1007/s12110-020-09375-4

Abstract: Although subsistence hunting is cross-culturally an activity led and practiced mostly by men, a rich body of literature shows that in many small-scale societies women also engage in hunting in varied and often inconspicuous ways. Using data collected among two contemporary forager-horticulturalist societies facing rapid change (the Tsimane’ of Bolivia and the Baka of Cameroon), we compare the technological and social characteristics of hunting trips led by women and men and analyze the specific socioeconomic characteristics that facilitate or constrain women’s engagement in hunting. Results from interviews on daily activities with 121 Tsimane’ (63 women and 58 men) and 159 Baka (83 women and 76 men) show that Tsimane’ and Baka women participate in subsistence hunting, albeit using different techniques and in different social contexts than men. We also found differences in the individual and household socioeconomic profiles of Tsimane’ and Baka women who hunt and those who do not hunt. Moreover, the characteristics that differentiate hunter and non-hunter women vary from one society to the other, suggesting that gender roles in relation to hunting are fluid and likely to change, not only across societies, but also as societies change.

Los Angeles’ Zones of Choice: The ZOC program boosted test scores & college enrollment markedly, closing achievement & college enrollment gaps between ZOC neighborhoods & the rest of the district

The Impact of Neighborhood School Choice: Evidence from Los Angeles’ Zones of Choice. Christopher Campos and Caitlin Kearns. Job Market Paper, November 8, 2020. https://www.cqcampos.com/research

Abstract: This paper evaluates the Zones of Choice (ZOC) program in Los Angeles, a school choice initiative that created small high school markets in some neighborhoods but left traditional attendance zone boundaries in place throughout the rest of the district. We leverage the design of the program to study the impact of neighborhood school choice on student achievement, college enrollment, and other outcomes using a matched difference-in-differences design. Our findings reveal that the ZOC program boosted test scores and college enrollment markedly, closing achievement and college enrollment gaps between ZOC neighborhoods and the rest of the district. These gains are explained by general improvements in school effectiveness rather than changes in student match quality, and school-specific gains are concentrated among the lowest-performing schools. We interpret these findings through the lens of a model of school demand in which schools exert costly effort to improve quality. The model allows us to measure the increase in competition facing each ZOC school based on household preferences and the spatial distribution of schools. We demonstrate that the effects of ZOC were larger for schools exposed to more competition, supporting the notion that competition is a key channel driving the impacts of ZOC. In addition, demand estimates suggest families place a larger weight on school quality compared to peer quality, providing schools the right competitive incentives. An analysis using randomized admission lotteries shows that the treatment effects of admission to preferred schools declined after the introduction of ZOC, a pattern that is explained by the relative improvements of less-preferred schools. Our findings demonstrate the potential for public school choice to improve student outcomes while also underscoring the importance of studying market-level impacts when evaluating school choice programs.

It seems we can use smart-phones to increase physical affection, intimacy and security in couples

Can we use smart-phones to increase physical affection, intimacy and security in couples? Preliminary support from an attachment perspective. Kerem Besim Durbin et al. Journal of Social and Personal Relationships, November 3, 2020. https://doi.org/10.1177/0265407520970278

Abstract: This study investigated whether physical affection is causally associated with momentary intimacy and security by manipulating physical affection. We used a GPS-based smart-phone application as ecological momentary intervention that prompted participants to show physical affection to their partner when they were in the same location. We also investigated whether attachment style and attachment functioning moderated the effects of the manipulation. Thirty-nine couples were assigned to experimental (N = 20) and control (N = 19) groups for 2 weeks. Multilevel dyadic data analysis revealed significantly higher momentary intimacy in the experimental group, even when spontaneous physical affection was controlled; there was no significant change for momentary security. While attachment style did not moderate the effect of manipulation for either outcome, attachment functioning significantly moderated the effect on security. This is the first study to show evidence that physical affection, when instructed by a device, is causally linked to increased momentary intimacy in daily life.

Keywords: Attachment, ecological momentary intervention, intimacy, physical affection, romantic relationships, security, touch

Letters to Our Future Selves? Failed High-Powered Replication Attempts Question Effects on Future Orientation, Delinquent Decisions, and Risky Investments

Letters to Our Future Selves? High-Powered Replication Attempts Question Effects on Future Orientation, Delinquent Decisions, and Risky Investments. Laura Quinten, Anja Murmann, Hanna Genau, Rafaela Warkentin, Rainer Banse. Social Cognition, July 2020. https://www.researchgate.net/publication/343188765

Abstract: Enhancing people’s future orientation, in particular continuity with their future selves, has been proposed as promising to mitigate self-control-related problem behavior. In two pre-registered, direct replication studies, we tested a subtle manipulation, i.e., writing a letter to one’s future self, in order to reduce delinquent decisions (van Gelder et al., 2013, Study 1) and risky investments (Monroe et al., 2017, Study 1). With samples of N = 314 and N = 463, i.e., 2.5 times the original studies’ sample sizes, the results suggested that the expected effects are either non-existent or smaller than originally reported, and/or dependent on factors not examined. Vividness of the future self was successfully manipulated in Study 2, but manipulation checks overall indicated that the letter task is rather not reliable to alter future orientation. We discuss ideas to integrate self-affirmation approaches, and to test less subtle manipulations in samples with substantial, myopia-related self-control deficits.

Rearming after Jim Crow: We find that lynchings decrease with greater Black firearm access; also, there was a frequent misclassification of homicides as accidents, which diminish after Blacks rearm

Firearms and Violence Under Jim Crow. Michael D. Makowsky, Patrick L. Warren. November 9, 2020. https://static1.squarespace.com/static/5329e895e4b09fd4786211a3/t/5fa9630d4e5ce030c7d36d79/1604936463367/Guns_under_Jim_Crow_Nov2020_circ.pdf

Abstract: We assess firearm access in the U.S. South by measuring the fraction of suicides committed with firearms. Black residents of the Jim Crow South were disarmed, before re-arming themselves during the Civil-Rights Era. We find that lynchings decrease with greater Black firearm access. During the Civil-Rights Movement, both the relative Black homicide and Black “accidental death by firearm” rates decrease with Black firearm access, indicating frequent misclassification of homicides as accidents. In the contemporary era, greater firearm access correlates with higher Black death rates. We find that firearms offered an effective means of Black self-defense in the Jim Crow South.

Counterfactual thinking and facial expressions among Olympic medalists: A conceptual replication of Medvec, Madey, and Gilovich’s (1995) findings

Hedgcock, W. M., Luangrath, A. W., & Webster, R. (2020). Counterfactual thinking and facial expressions among Olympic medalists: A conceptual replication of Medvec, Madey, and Gilovich’s (1995) findings. Journal of Experimental Psychology: General, Nov 2020. https://doi.org/10.1037/xge0000992

Rolf Degen's take: https://twitter.com/DegenRolf/status/1326175281221165056

Abstract: Counterfactual thinking, or contemplation of “what could have been,” influences facial expressions of Olympic medalists. Medvec, Madey, and Gilovich (1995) revealed that bronze medalists appeared happier than silver medalists after competition in Olympic events. Two prominent explanations for this phenomenon exist: the formation of (a) category-based counterfactuals and (b) expectation-based counterfactuals. First, Medvec et al. (1995) demonstrated that silver medalists formed an upward comparison to the gold medalist with thoughts of “I almost won Gold” while bronze medalists formed a downward comparison to a fourth place finisher with thoughts of “at least I won a medal.” A second explanation suggests that medalists form expectation-based counterfactuals in which silver medalists are more disappointed since their prior expectations for performance were higher than bronze medalists (McGraw, Mellers, & Tetlock, 2005). To test these 2 explanations, we compiled a large dataset of medal stand photographs from the Olympic Multimedia Library and Getty Images for the 2000–2016 Olympic games as well as Sports Illustrated’s predictions. Using automated facial expression encoding, we conducted a conceptual replication of prior work and found evidence supporting both category-based and expectation-based counterfactual accounts of Olympic medalists’ expressions.

Pupillometry and Hindsight Bias: Physiological Arousal Predicts Compensatory Behavior

Pupillometry and Hindsight Bias: Physiological Arousal Predicts Compensatory Behavior. Willem W. A. Sleegers, Travis Proulx, Ilja van Beest. Social Psychological and Personality Science, November 10, 2020. https://doi.org/10.1177/1948550620966153

Rolf Degen's take: https://twitter.com/DegenRolf/status/1326117586048790529

Abstract: According to violation–compensation models of cognitive conflict, experiences that violate expected associations evoke a common, biologically based syndrome of aversive arousal, which in turn motivates compensation efforts to relieve this arousal. However, while substantial research shows that people indeed respond with increased arousal to expectancy violating events, evidence for the motivating role of arousal is rarely found. In two within-subjects studies (N = 44 and N = 50), we demonstrate evidence for the motivating role of arousal in this violation–compensation process among university students. Using pupillometry and the hindsight bias phenomenon, we show that people respond with greater arousal when presented with expectancy violating information. In turn, we show that the pupillary response is positively related to the amount of hindsight bias being displayed. These findings provide further insights into the process underlying the hindsight bias and, crucially, support key predictions following from threat–compensation models.

Keywords: threat–compensation, arousal–behavior link, pupillometry, hindsight bias

Discussion

We aimed to demonstrate the first direct link between physiological arousal and compensatory behavior. While the results of each study separately were not conclusive, the results from both studies combined did provide evidence for this link. Greater pupil dilation in response to an unexpected correct answer was associated with more hindsight bias. That is, participants shifted their second answer more toward the factual question’s correct answer, relative to their first answer, when they showed a larger physiological response to the correct answer to the question. This compensatory response following increased arousal is consistent with violation–compensation theories (Jonas et al., 2014; McGregor et al., 2012), specifically with the shared assumption that inconsistencies evoke arousal that causes compensation reactions.

That expectancy violations induce a syndrome of aversive arousal is an important tenet of violation–compensation theories. There is abundant evidence for this first link between expectancy violations and arousal, whether the expectancy violation involves perceptual anomalies (Sleegers et al., 2015), cognitive dissonance (Gerard, 1967), self-view inconsistencies (Ayduk et al., 2012), worldview violations (Townsend et al., 2010), or category-based violations (Mendes et al., 2007). Evidence for the second link, between arousal and the subsequent compensatory behavior, is rarely observed and limited to indirect assessments of arousal such as self-report measures (Laurin et al., 2008; McGregor et al., 2013, Experiment 4; Plaks et al., 2005) and the misattribution of arousal paradigm (Kay et al., 2010; Losch & Cacioppo, 1990; Proulx & Heine, 2008; Zanna & Cooper, 1974). Our findings provide more direct evidence for the often postulated relationship between arousal and compensatory behaviors following expectancy violations.

Two reasons might explain why we were able to demonstrate a link between arousal and compensatory behavior. First, recent developments in eye tracker technology have made this technology exceptionally noninvasive. Consequently, an eye tracker is less likely to evoke arousal that interferes with the arousal process underlying violation–compensation reactions. Second, we repeatedly presented participants with an expectancy violation and an opportunity to compensate—a requirement for physiological measures to improve reliability.

Limitations and Future Research

In our studies, we relied on pupillometry to assess an aversive state of arousal following negative belief feedback because threat–compensation theories strictly postulate a state of aversive arousal to motivate subsequent compensatory behaviors. However, while pupillometry is a valid measure of physiological arousal, it is not a direct measure of aversive arousal (e.g., Bradley et al., 2008). We believe our findings nevertheless plausibly indicate a state of aversive arousal. Studies have shown that negative belief feedback and states of surprise are (at least initially) experienced as aversive (Hajcak & Foti, 2008; Noordewier & Breugelmans, 2013; Noordewier et al., 2016). In addition, alternative explanations such as curiosity-driven responses were ruled out by the data (see Online Appendix C). We therefore believe our findings present a strong contribution to models of threat–compensation.

It should be noted that we relied mostly on epistemic threats rather than more severe existential threats such as those relating to one’s identity or freedom. Epistemic threats were chosen in order to be able to repeatedly present participants with threats and compensation opportunities. This would not be feasible when more impactful threats are used because the physiological response would likely carry over between trials and affect the relationship between arousal and compensation. Moreover, the theoretical perspectives that guide this research share the explicit premise that the response to epistemic threats generalize to other types of threats (Heine et al., 2006; Jonas et al., 2014; Proulx & Inzlicht, 2012). In fact, it has been demonstrated that the experience of inconsistency, such as those experienced by our participants, can evoke the same compensation behaviors as existential threats (e.g., nonsense word pairs and identity violations; Randles et al, 2011). Nevertheless, the threat–compensation literature would benefit from more empirical demonstrations of the kind presented here.

Aside from expectancy violations inducing physiological arousal, and physiological arousal motivating compensatory behavior, compensatory behavior should also reduce the physiological arousal. We did not assess this third link. Using the present studies’ design, it might be possible to demonstrate the entire causal link by having participants again see the correct answers. We predict that instead of the positive relationship between pupil size and hindsight bias found in the present study, a negative relationship between hindsight bias and pupil size should be found.

Finally, in the present studies, we used the hindsight bias as a way to repeatedly assess compensatory behaviors following belief violations. It may be argued that due to the many trials, participants may not have always remembered their initial answer and that this ultimately shaped their hindsight bias responses. However, research on the hindsight bias largely supports a biased reconstruction view rather than a memory impairment process (Stahlberg & Maass, 1997). Our findings also contribute to the research on the hindsight bias. Several processes have been proposed to explain the hindsight bias (Hawkins & Hastie, 1990), including motivational accounts (Campbell & Tesser, 1983; Fischhoff, 1975; Musch, 2003). Our results are consistent with a motivational interpretation of the hindsight bias, thereby also contributing to research on the hindsight bias phenomenon.

We did employ a memory design to measure hindsight bias. Importantly, this memory-based design, although effective in demonstrating a hindsight bias, might be less effective in evoking a hindsight bias than other designs such as the hypothetical design (Pohl, 2007), in which participants are asked to respond as if they had not been told the correct answer. After all, a memory task is about recalling a previously reported answer; and when the time lag is not substantial, people can with relative ease recall their answer. For this reason, the memory design can be potentially improved in future studies by extending the retention interval between the first and second responses.

The framing of zero has a substantial effect on judgment: In the context of a simple gamble a small loss is more attractive than gaining nothing, but the same small loss is less attractive than losing nothing

Framing Zero: When Losing Nothing is Better Than Gaining Nothing. Marcus Wardley, Max Alberhasky. Journal of Behavioral and Experimental Economics, November 9 2020, 101641. https://doi.org/10.1016/j.socec.2020.101641

Rolf Degen's take: https://twitter.com/DegenRolf/status/1326095730495401984

Highlights

• The framing of zero has a substantial effect on judgment and decision-making

• A loss is more attractive than gain nothing but less attractive than lose nothing

• These effects are consistent with an affect and reference point explanation

Abstract: The framing of zero has a substantial effect on judgment and decision-making, a fact which is often ignored or unacknowledged by many authors. Although prior research has shown that zero carries a special meaning, no prior research has specifically examined the framing of zero. Across four studies, the current research demonstrates the effect the framing of zero has on judgment and decision-making and explores the underlying mechanisms. In the context of a simple gamble a small loss is more attractive than gaining nothing, but the same small loss is less attractive than losing nothing. The present studies test and support an explanation of these findings based on the concept of reference points and the affect heuristic. The framing of zero in these decision problems acts as a point of comparison, or reference point, affecting how evaluators feel about the bet. These results establish the importance of framing zero in judgment and decision-making and sheds light on the mediators of this effect.

Keywords: framingzerogamblesaffectreference points

Subjects in ambiguous cases used punishment for reputational gain, punishing at higher rates when their behavior was observable to their audience, even when personally were less supportive of punishment

Jordan, Jillian, and Nour Kteily. 2020. “People Punish Moral Transgressions for Reputational Gain, Even When They Personally Question Whether Punishment Is Merited.” PsyArXiv. March 21. doi:10.31234/osf.io/97nhj

Rolf Degen's take: https://twitter.com/DegenRolf/status/1326061880314634240

Abstract: People punish wrongdoers in order to appear virtuous. But is this true even in ambiguous situations, where people may question whether punishment is merited? Across three studies (total n = 4863), we investigate the willingness of liberal subjects to enact costly punishment of a university professor facing sexual harassment allegations. In our ambiguous (vs. unambiguous) condition, the allegations were less severe and the evidence for them was weaker—creating a murkier moral case for the relevant punishment. And yet in Study 1, we created a context in which subjects in both conditions expected punishing to look equally good in the eyes of a salient audience. We achieved this by describing the audience as more ideological in the ambiguous condition, because people expected more ideological audiences to be more supportive of punishment. Next, using this context, Study 2 measured the power of (equally strong) reputational incentives to encourage ambiguously vs. unambiguously deserved punishment. Subjects in the ambiguous condition used punishment for reputational gain, punishing at higher rates when their behavior was observable to their audience. In fact, making punishment observable was as effective at increasing punishment in the ambiguous (vs. unambiguous) condition—even though subjects in the ambiguous condition were, on average, far less personally supportive of punishment. Finally, in Study 3, reputational incentives again encouraged ambiguously-deserved punishment—even among individuals who, before learning that punishment could enhance their reputation, reported reservations about its morality. We thus find that people punish for reputational gain, even when they personally question whether punishment is merited.

The herbivore’s dilemma in Japan: In 2015 around 1 in 4 women and 1 in 3 men in their thirties were unmarried and not in a heterosexual relationship; half of the singles reported no interest in romantic relationships

The herbivore’s dilemma: Trends in and factors associated with heterosexual relationship status and interest in romantic relationships among young adults in Japan—Analysis of national surveys, 1987–2015. Cyrus Ghaznavi, Haruka Sakamoto, Shuhei Nomura, Anna Kubota, Daisuke Yoneoka, Kenji Shibuya, Peter Ueda. PLOS One, November 9, 2020. https://doi.org/10.1371/journal.pone.0241571

Abstract

Background: It has been suggested that an increasing proportion of young adults in Japan have lost interest in romantic relationships, a phenomenon termed “herbivorization”. We assessed trends in heterosexual relationship status and self-reported interest in heterosexual romantic relationships in nationally representative data.

Methods: We used data from seven rounds of the National Fertility Survey (1987–2015) and included adults aged 18–39 years (18–34 years in the 1987 survey; sample size 11,683–17,675). Current heterosexual relationship status (married; unmarried but in a relationship; single) was estimated by sex, age group and survey year, with singles further categorized into those reporting interest vs. no interest in heterosexual romantic relationships. Information about same-sex relationships were not available.

Results: Between 1992 and 2015, the age-standardized proportion of 18-39-year-old Japanese adults who were single had increased steadily, from 27.4 to 40.7% among women and from 40.3 to 50.8% among men. This increase was largely driven by decreases in the proportion of married women aged 25–39 years and men aged 30–39 years, while those in a relationship had increased only slightly for women and remained stable for men. By 2015, the proportion of single women was 30.2% in those aged 30–34 years and 24.4% in those aged 35–39 years. The corresponding numbers for men were 39.3% and 32.4%. Around half of the singles (21.4% of all women and 25.1% of all men aged 18–39 years) reported that they had no interest in heterosexual romantic relationships. Single women and men who reported no interest in romantic relationships had lower income and educational levels and were less likely to have regular employment compared to those who reported such an interest.

Conclusions: In this analysis of heterosexual relationships in nationally representative data from Japan, singlehood among young adults had steadily increased over the last three decades. In 2015 around one in four women and one in three men in their thirties were unmarried and not in a heterosexual relationship. Half of the singles reported no interest in romantic relationships and these women and men had lower income and educational levels and were less likely to have regular employment.

Discussion

Intimate relationships constitute an important component of human fertility and life satisfaction and are associated with better health outcomes [6, 13–16]. As such, a purportedly decreasing interest in sex and romantic relationships has brought young Japanese adults under national scrutiny and fostered unease in light of the country’s rapidly ageing population, low birth rates, and large number of individuals living in social isolation [25, 26]. In this study, which is the first to investigate the phenomenon of so-called “herbivore” young adults in nationally representative data in Japan, we assessed changes in, and sociodemographic factors associated with, heterosexual relationship status and reporting of no interest in heterosexual romantic relationships.

Between 1992 and 2015, the age-standardized proportion of 18-39-year-old Japanese adults who were single (unmarried and not in a heterosexual relationship) had increased steadily, from 27.4 to 40.7% among women and from 40.4 to 50.8% among men, with these numbers corresponding an increase of 2.2 million single women and 1.7 million single men in the investigated age range. The increase was largely driven by increases in singlehood among women aged 25–39 years and men aged 30–39 years. By 2015, around one in four women and one in three men in their thirties were single. Our findings show that the decline in marriage among young adults [9] indeed reflects an increase in singlehood as the proportion who were unmarried and in a relationship rose only slightly among women and remained stable among men. Notably, being in a relationship became increasingly uncommon with higher age and among adults in their thirties, this group was so small that the proportion who were unmarried largely equaled the proportion who were single.

Around one in five women and men aged 18–39 years in 2015 were single while reporting that they had no interest in heterosexual romantic relationships. It should be assumed that a proportion of these individuals have interest, or are currently in, non-heterosexual sexual or romantic relationships. Moreover, the term “kousai” which was used in the question about interest in romantic relationships was not defined in the National Fertility Survey. This term is commonly used to refer to the act of engaging in a relationship with a romantic/sexual partner, but as with the word “dating,” the level of commitment to such a relationship is uncertain; it is possible that a proportion of those who answered that they had no interest in a romantic relationship may have had interest in sexual or romantic pursuits but preferred not to be in a stable relationship at the time of survey participation. However, over half of women and men who reported no interest in heterosexual romantic relationships had no heterosexual experience, indicating that many of these individuals are indeed sexually inactive.

While interpretation of the results on income and employment status among women is made difficult by the relatively large proportion of married women who are housewives [27], we note that single women without interest in romantic relationship had lower educational levels and income than single women with such an interest. For men, there was a pronounced gradient in income and occupational status across categories of relationship status and interest in relationships. For example, the proportion with regular employment was highest among married men (85.8%) and decreased stepwise for those in a relationship (63.2%), single with interest in relationships (53.2%), and single with no interest (42.6%). In age-adjusted analyses, married men were twice as likely to have an annual income of JPY 5 million as compared to those in a relationship and those who were single with an interest in relationship and more than three times as likely to have such an income compared to those without interest in romantic relationships.

The herbivore stereotype has typically been portrayed as a timid individual (most of the time male), seemingly indifferent to sex and romance; in other words, “herbivore” is largely described as a type of personality or a set of behaviors secondary to sexual interests [7, 8, 28]. This notion is challenged by the association of lower education, low income, and a lack of regular employment with reporting no interest in relationships among single women and men. It is likely that aspirations and outcomes in the labor and partner market have common determinants such as personality, values, physical appearance and physical and mental health status, and the associations may not represent causality. Nonetheless, high and stable incomes are important predictors of appeal in the partner market, particularly for men [10, 29–31], indicating that individuals with lower income may have difficulties in finding romantic partners. In addition, one could speculate that precarious employment and financial insecurity may contribute to decreased resources, motivation, and opportunities for pursuing romantic relationships [18]. Indeed as shown in our study and in previous analyses [32], income is strongly associated with marriage among Japanese men. Notably, in a study using longitudinal data (2002–2006) from a nationally representative sample of women [33], those with higher earnings (before marriage) were more likely to marry at any age than those with lower earnings. Moreover, women with a university or junior college degree were more likely to be married at the age of 38 years as compared with those with a high school degree or less, indicating that, perhaps contrary to popular belief [34], high earning potential and education constitute advantages in the partner market also for Japanese women. As such, it could be hypothesized that for some women and men, the reporting of no interest in romantic relationships may represent an adjustment of their expectations, or resignation, given their current lack of access to romantic partners and inability to pursue them, while they would be otherwise interested if they were to meet suitable partners. In support of this hypothesis, we found that around two thirds of the women and men reporting no interest in romantic relationships answered that they wished to get married in their lifetime and that around one third reported that a major reason for not getting married was that they had not met a suitable partner. It should also be noted that the proportion who reported no interest in romantic relationships in 2015 decreased with age and the proportions were largely similar in 2010 vs. 2015, indicating that some individuals get married regardless of their reported interest in romantic relationships.

Although there are other types of social connections which may provide benefits to health and life satisfaction [35–39], and while some individuals may prefer to live without romantic relationships, the large proportion of young adults that has lost interest, given up, or find it hard to form romantic relationships may have important implications for public health and fertility. Our findings indicate a possibility that policy measures aimed at improving employment opportunities and addressing economic disadvantage may also lead to increased interest in romantic relationships and marriage. Moreover, income and employment status are considered as important spouse-selection criteria in Japan, especially for women who evaluate potential husbands [10]. Given that most unmarried individuals wish to get married and the most common reason for staying single is that no suitable partner is available [10], it could be speculated that some individuals are reluctant to form romantic relationships with partners who do not fulfill their partner-selection criteria for marriage (e.g. with respect to income and employment status) but who are otherwise of romantic and sexual interest. This hypothesis is supported by our finding that almost no individuals in their late thirties were unmarried and in a romantic relationship, implying that the promotion of marriage as the most socially acceptable form of relationship between adults and a necessary step for co-habitation and family formation could constitute a barrier to forming romantic relationships in Japan.

While the decline in marriage rates has been established in many high-income countries [40], data on relationship status among unmarried individuals is scarce. A situation similar to that in Japan may be ongoing in South Korea, where a national survey found that 68% of unmarried women and 74% of unmarried men aged 20–44 years were not in heterosexual relationships and that young adults listed lack of money as an important reason for giving up dating [41, 42]. In the US and Europe, higher earnings and education have been associated with a higher likelihood of marriage among both women and men [43–45], although it is not known how these factors influence interest in romantic relationships. We found that the proportion of Japanese women who were single was 65.6% (18–24 years), 41.9% (25–29 years), 30.2% (30–34 years), and 24.4% (35–39 years), and the proportion of men who were single was 75.9% (18–24 years), 55.1% (25–29 years), 39.3% (30–34 years), and 32.4% (35–39 years). Our analyses of nationally representative survey data from Britain (Natsal-3, 2010–2012) and the US (General Social Survey, 2012–2018) showed that singlehood tends to be less common in these countries. In Britain, the proportion of women who were single (not married/living together with partner and not in a stable relationship) was 41.5% (18–24 years), 23.6% (25–29 years), 16.3% (30–34 years), and 14.0% (35–39 years). The corresponding numbers for men were 52.6% (18–24 years), 32.5% (25–29 years), 14.7% (30–34 years), and 11.8% (35–39 years). In the US, the proportion of women who were single was 62.6% (18–24 years), 25.2% (25–29 years), 20.0% (30–34 years), and 16.6% (35–39 years). The corresponding numbers for men tended to be closer to those we observed in Japan: 81.4% (18–24 years), 55.8% (25–29 years), 35.9% (30–34 years), and 22.0% (35–39 years). Of note, however, are the slightly different definitions of single used (S1 File), and that the estimates for Britain and the US accounted for any stable relationship, regardless of the gender of the partner, while only heterosexual relationships were considered in Japan.

Our study has limitations. First, as data on relationship status and interest in romantic relationships was self-reported, findings may have been affected by social desirability bias [46]; the risk of such a bias, however, may have been mitigated by the survey’s use of self-administered questionnaires [47]. Second, although the response rate in the National Fertility Survey was high (70.0–83.8% among unmarried individuals and 85.7–92.5% among married couples) and the sample was weighted so that it was representative of the Japanese population in terms of sex, age, and marital status, non-response might have introduced bias in our results. Third, the large sample size may have resulted in small differences in the investigated variables being statistically significant and interpretation of the findings should consider the absolute differences. Fourth, because the data were cross-sectional, we could not assess temporality of the associations of sociodemographic variables with relationship status and interest in romantic relationships. Finally, as the questions asked in the National Fertility Survey were limited to heterosexual relationships, we could not assess other types of relationships. Data on gay, lesbian, bisexual, and transgender groups in Japan is scarce [48], and questions targeted to the experiences of these groups should be included in future surveys.

From 2019... Some apes don't seem to have a sense of procedural (un)fairness, not getting upset when they have to spend greater effort for the same reward than their peers

From 2019... The Biology of Fairness. Sarah F. Brosnan. Chapter 2 in Social Psychology and Justice. Edited By E. Allan Lind. November 2019. https://www.taylorfrancis.com/books/e/9781003002291/chapters/10.4324/9781003002291-2

Rolf Degen's take: https://twitter.com/DegenRolf/status/1325861779474354182

Abstract: Humans are not the only species that is sensitive to outcome inequality. Other species, too, respond negatively to getting less than a social partner, and this breadth suggests a common biological foundation. Across species, negative responses to inequity are linked to the degree to which those species cooperate, and within cooperative tasks, subjects are sensitive to inequity, refusing to work with partners who do not equitably share rewards. Together, these results suggest that inequity aversion evolved because it provides a mechanism by which individuals can judge the relative value of their cooperative partners. In addition, humans and chimpanzees respond negatively to getting more than a partner, suggesting that they can inhibit this short term benefit for the long term gain of maintaining cooperative relationships. The comparative approach has been extremely useful in highlighting the roots of inequity responses and, thereby, helping us to better understand our own sense of fairness.

We did not find any evidence of influence of alcohol consumption on changes in brain volume over a 2-year period in 40–60-year-olds

Midlife alcohol consumption and longitudinal brain atrophy: the PREVENT-Dementia study. Michael J. Firbank, John T. O’Brien, Karen Ritchie, Katie Wells, Guy Williams, Li Su & Craig W. Ritchie. Journal of Neurology volume 267, pages3282–3286. June 20 2020. https://link.springer.com/article/10.1007/s00415-020-10000-8

Abstract

Background and aims: Consensus is lacking on whether light to moderate consumption of alcohol compared to abstinence is neuroprotective. In this study, we investigated the relationship between self-reported alcohol use and brain volume change over 2 years in middle-aged subjects.

Methods: A sample of 162 subjects (aged 40–59 at baseline) from the PREVENT-Dementia programme underwent MRI scans on two separate occasions (mean interval 734 days; SD 42 days). We measured longitudinal rates of brain atrophy using the FSL Siena toolbox, and change in hippocampal volume from segmentation in SPM.

Results: Controlling for age and sex, there were no significant associations of either total brain, ventricular, or hippocampal volume change with alcohol consumption. Adjusting for lifestyle, demographic and vascular risk factors did not alter this.

Conclusions: We did not find any evidence of influence of alcohol consumption on changes in brain volume over a 2-year period in 40–60-year-olds.

Discussion

Contrary to our hypothesis, we did not observe any significant association between alcohol consumption and longitudinal brain volume changes. Rather, we saw a non-significant trend of 14–21 units of alcohol (vs. abstinence) associated with preserved total brain volume.

Studies of alcohol on cognition or brain structure have confounds due to social and demographic factors, with age, years of education, and social class all being linked to both alcohol consumption and brain volume. Our study, looking at brain volume change over 2 years within individuals overcomes to some extent these confounds, and including the lifestyle, demographic and vascular health factors in our analysis did not change our findings.

Combined with the previous conflicting reports on the benefit or otherwise of mild to moderate alcohol consumption, our data suggest at least that consumption of 7–21 units per week is not associated with marked brain atrophy over a 2-year period in midlife.

Limitations of the study include that alcohol consumption was estimated from subject report, and the relatively short follow-up of 2 years. The participants were mostly female, limiting the extrapolation to the general population.

In summary, we did not find any evidence of influence of alcohol consumption on changes in brain volume over a 2-year period in 40–60-year-olds.

In 1500 reports of positive tears, 13124 participants, 40 diverse countries, 24 languages they found 4 qualitatively different types of positive tears, achievement, beauty, affection, and amusement tears

Zickfeld, Janis, Beate Seibt, Ljiljana B. Lazarevic, Iris Zezelj, and Ad Vingerhoets. 2020. “A Model of Positive Tears.” PsyArXiv. November 8. doi:10.31234/osf.io/sf7pe

Rolf Degen's take: https://twitter.com/DegenRolf/status/1325665261928804353

Abstract: Although several scholars acknowledge the existence of tears of joy, there is little systematic theoretical or empirical evidence on how positive tears are experienced, what elicits them, what actions or impulses they motivate in the crier, how they differ from tears of sadness or distress and whether there are different types. We systematically investigated these issues and drafted a first taxonomic model of positive tears. Drawing on more than 1500 reports of positive tears and including 13124 participants from 40 diverse countries and 24 languages, the studies employed a strong mixture of quantitative and qualitative techniques. The final results showed evidence of the occurrence of positive tears and found four qualitatively different types and profiles that we termed achievement, beauty, affection, and amusement tears. Achievement tears are often shed in contexts of extraordinary performance or when someone overcomes an obstacle and often include feelings of pride. Beauty tears occur commonly in situations of overwhelming elegance or beauty, including nature, music or visual arts, and feature feelings of awe or experiencing chills. Affectionate tears are often experienced in situations including unexpected kindness or exceptional love such as wedding ceremonies or reunions and often feature feelings of warmth, increased communality, and feeling touched or compassionate. Finally, amusement tears are shed when something especially funny occurs and include feelings of amusement or lightness and the inclination to laugh or giggle. We also investigated cross-cultural and inter-individual differences with regard to these categories and discuss limitations and implications of our taxonomy of positive tears.