Wednesday, October 7, 2020

Work from a more diverse array of societies suggests there may be important variation in how much people rely on mental states, with people in some societies judging accidental harms just as harshly as intentional ones

Kinship intensity and the use of mental states in moral judgment across societies. Cameron M. Curtin et al. Evolution and Human Behavior, Volume 41, Issue 5, September 2020, Pages 415-429. Ungated:

Abstract: Decades of research conducted in Western, Educated, Industrialized, Rich, & Democratic (WEIRD) societies have led many scholars to conclude that the use of mental states in moral judgment is a human cognitive universal, perhaps an adaptive strategy for selecting optimal social partners from a large pool of candidates. However, recent work from a more diverse array of societies suggests there may be important variation in how much people rely on mental states, with people in some societies judging accidental harms just as harshly as intentional ones. To explain this variation, we develop and test a novel cultural evolutionary theory proposing that the intensity of kin-based institutions will favor less attention to mental states when judging moral violations. First, to better illuminate the historical distribution of the use of intentions in moral judgment, we code and analyze anthropological observations from the Human Area Relations Files. This analysis shows that notions of strict liability—wherein the role for mental states is reduced—were common across diverse societies around the globe. Then, by expanding an existing vignette-based experimental dataset containing observations from 321 people in a diverse sample of 10 societies, we show that the intensity of a society’s kin-based institutions can explain a substantial portion of the population-level variation in people’s reliance on intentions in three different kinds of moral judgments. Together, these lines of evidence suggest that people’s use of mental states has coevolved culturally to fit their local kin-based institutions. We suggest that although reliance on mental states has likely been a feature of moral judgment in human communities over historical and evolutionary time, the relational fluidity and weak kin ties of today’s WEIRD societies position these populations’ psychology at the extreme end of the global and historical spectrum.

Keywords: Moral judgment, mental states, theory of mind, kinship intensity, cultural evolution, WEIRD

Feedback Between Psychological Science and Policy in the Context of Same-Sex Couples

Feedback Between Psychological Science and Policy in the Context of Same-Sex Couples. Adam W. Fingerhut, David M. Frost. Policy Insights from the Behavioral and Brain Sciences, October 1, 2020.

Abstract: Psychological science informed recent policy changes granting increased rights for same-sex couples. Understanding that the link between science and policy goes both ways, how should policy inform the next generation of research concerning same-sex couples and sexual minority individuals? This article presents ways that psychological research influenced marriage policy and then puts forth suggestions for future research for the attention of scholars, funders, and policymakers. These include examinations of minority stress in the age of marriage equality; new stressors for same-sex couples including legal divorce; relationship expectations and experiences for emerging adults; and the potential impact of marriage equality for mixed-sex couples including a further challenge to strict gender roles in marriage. The article ends by acknowledging the need for continued application of research to emerging policy questions affecting same-sex couples and sexual minority individuals.

Keywords: same-sex couples, marriage equality, policy, romantic relationships, minority stress

Marriage does not relate to major histocompatibility complex: a genetic analysis based on 3691 couples

Marriage does not relate to major histocompatibility complex: a genetic analysis based on 3691 couples. Ilona Croy, Gerhard Ritschel, Denise Kreßner-Kiel, Laura Schäfer, Thomas Hummel, Jan Havlíček, Jürgen Sauter, Gerhard Ehninger and Alexander H. Schmidt. Proceedings of the Royal Society B: Biological Sciences, Volume 287, Issue 1936, October 7 2020.

Abstract: Optimization of chances for healthy offspring is thought to be one of the factors driving mate choice and compatibility of the major histocompatibility complex (MHC) is assumed to determine the offspring's fitness. While humans have been claimed to be able to perceive information of MHC compatibility via the olfactory channel, it remains unknown whether humans use such information for mate choice. By investigation of 3691 married couples, we observed that the high polymorphism of MHC leads to a low chance for homozygous offspring. MHC similarity between couples did not differ from chance, we hence observed no MHC effect in married couples. Hormonal contraception at the time of relationship initiation had no significant effect towards enhanced similarity. A low variety of alleles within a postcode area led to a higher likelihood of homozygous offspring. Based on this data, we conclude that there is no pattern of MHC dis-assortative mating in a genetically diverse Western society. We discuss the question of olfactory mate preference, in-group mating bias and the high polymorphism as potential explanations.

Neighbourhood wealth, not urbanicity or population density, predicts prosociality towards strangers

Neighbourhood wealth, not urbanicity, predicts prosociality towards strangers. Elena Zwirner and Nichola Raihani. Proceedings of the Royal Society B: Biological Sciences, October 7 2020.

Abstract: Urbanization is perhaps the most significant and rapid cause of demographic change in human societies, with more than half the world's population now living in cities. Urban lifestyles have been associated with increased risk for mental disorders, greater stress responses, and lower trust. However, it is not known whether a general tendency towards prosocial behaviour varies across the urban–rural gradient, or whether other factors such as neighbourhood wealth might be more predictive of variation in prosocial behaviour. Here, we present findings from three real-world experiments conducted in 37 different neighbourhoods, in 12 cities and 12 towns and villages across the UK. We measured whether people: (i) posted a lost letter; (ii) returned a dropped item; and (iii) stopped to let someone cross the road in each neighbourhood. We expected to find that people were less willing to help a stranger in more urban locations, with increased diffusion of responsibility and perceived anonymity in cities being measured as variables that might drive this effect. Our data did not support this hypothesis. There was no effect of either urbanicity or population density on people's willingness to help a stranger. Instead, the neighbourhood level of deprivation explained most of the variance in helping behaviour with help being offered less frequently in more deprived neighbourhoods. These findings highlight the importance of socio-economic factors, rather than urbanicity per se, in shaping variation in prosocial behaviour in humans.

4. Discussion

Our data do not support the idea that urbanicity is associated with reduced generalized prosociality. Instead, most of the variation in whether help was offered was explained by neighbourhood wealth, with help being more forthcoming in higher-wealth neighbourhoods. Our findings contrast with previous theories and empirical studies on the role of urbanicity in shaping prosocial behaviour (see [21,50] for reviews) but support more recent work that has implicated relative deprivation as being key to understanding variation in generalized prosociality and collective behaviour [3436,5154]. The effect of neighbourhood wealth on the tendency to help a stranger might help to explain why previous studies have reported decreased prosociality among urban dwellers. Although the pattern in the UK is quite mixed, there is quantitative evidence that rural areas are typically less deprived than more urban locations (a pattern than we also observe in the locations selected for this study) [42]. Previous findings that generalized cooperation is reduced in urban areas might, therefore, be masking the underlying instrumental variable, which relates to deprivation rather than to population density.

These data from a battery of real-world experiments lend more weight to the hypothesis that relative deprivation is negatively associated with generalized trust and prosociality. Several other studies have reported a similar pattern [34,5261]. In experimental settings, exposure to harsh environments has been associated with an increased willingness to defect in a Prisoner's Dilemma game, and a reduced tendency to send money to a partner in a Dictator Game [36,62,63], and experimentally induced financial deprivation can increase the willingness to cheat for financial rewards [64]. Studies using the lost letter technique to measure prosociality have consistently reported increased return rates from higher-wealth neighbourhoods [34,35,56]. Large-scale, survey-based studies report similar findings. One recent study using more than 30 000 observations based on nationally representative samples concluded that high socio-economic status was associated with increased willingness to donate to charity, to volunteer to help, to contribute a higher proportion of income to charity, and to choose the prosocial option in an economic game [59] (see also [58]), while another large study (a total sample of greater than 60 000 and with participants from more than 30 countries) reported positive effects of household income on tendency to volunteer or to donate to charity ([60], but see [65], who performed a similar study, obtaining a null result). Finally, a study using data from more than 40 000 responses to the World Values Survey and the European Values Study, respectively, also suggests a negative link between exposure to environmental harshness and the tendency to invest in cooperative behaviour [52].

Nevertheless, other studies have reported negative effects of socio-economic status on prosocial and ethical behaviour [6672]. We cannot account for the apparently contradictory findings in this field though we note that some of these earlier studies have been based on relatively small undergraduate samples [67,69] and several key results have failed to replicate in large-N, pre-registered replication attempts [73]. Other work has not found a main effect of social class on prosocial behaviour but has shown, instead, that the effect is moderated by third variables. For example, one study found that the effect of social class on social behaviour depends on whether the behaviour takes place in private or public [74], though we note that the effects of the interaction between class and anonymity on giving was inconsistent across different experiments in the study mentioned. Another study argued that the effect of social class on prosocial behaviour depends on whether lower-status individuals are exposed to high economic inequality [75], though two subsequent studies have failed to replicate this effect using similarly large datasets [58,60].

We note that our study differs from much of the work reported above in that we measured behaviour in the real world, rather than via online surveys or in the context of experimental games. In this true field experiment, it is possible that participants were also affected by the environment in which the behaviour was measured. For example, people are more likely to violate prosocial norms of collective behaviour where there is evidence that others do the same [76]—evidence that these norms are violated (e.g. litter and other indices of disorder) is typically higher in more deprived communities [77]. Other work has shown that prosocial behaviour is more likely when people have access to green space [78]. Importantly, access to green space is often lower in more deprived areas [77,79] or else is used less frequently by residents due to perceptions of being inaccessible or unsafe [79,80]. With our current dataset, it is impossible for us to determine whether the link between helping behaviour and deprivation pertains to the deprivation experienced by the participants or, alternatively, to the nature of the environment in which the studies were conducted, though we note that these explanations are not mutually exclusive.

Assuming that the negative association between neighbourhood levels of deprivation and the reduced tendency to help a stranger does exist, it begs the question as to how such a relationship might arise. There are several plausible routes by which deprivation might lead to reduced tendency to help a stranger. One of the most plausible routes might be through the effects that environmental harshness or unpredictability has on the tendency to invest to achieve larger rewards in the future, rather than taking immediately available, smaller pay-offs now. Investing to help a stranger has this incentive structure, where any downstream benefits of the helpful action are typically delayed and/or uncertain [38,81,82]. The effect of reduced income or lowered neighbourhood quality on the tendency to help a stranger could also be mediated by reduced social capital and generalized trust [8386]. For example, a natural experiment in Russia found that a 10% decrease in average national income following the 2009 recession was associated with a 5% decrease in social trust [87]. Given that one of the help measures in our study (dropped item) involved a live interaction with a stranger, trust may well have been a relevant concern for people deciding whether to help or not. Another potential explanation for the link between adversity and willingness to help a stranger might be the role of material security and how this impacts the scale at which people cooperate [8891]. In brief, this hypothesis predicts that as material security increases, people are more able to expand their social network, offering impartial help and cooperation to people beyond their core social group of known and regular interaction partners. We note that a prediction that derives from all these hypotheses (albeit one that we cannot test with our data) is that higher indices of deprivation in the UK will only affect the willingness to help a stranger, but not the willingness to help others that are part of one's existing community. Some empirical work supports the hypothesis that exposure to adversity or low socio-economic status is associated with an increased tendency to help friends or in-group members [70,71] though this hypothesis deserves further empirical attention.

We found mixed support for the hypothesis that help would be more likely when participants were directly requested to help. In the dropped item experiment, the direct request increased the likelihood of receiving help, whereas in the lost letter experiment, there was no difference in return rates across the direct request and no request conditions. These patterns may stem from the fact that the direct request in the dropped item experiment was made face-to-face, whereas in the lost letter experiment, the request was made remotely. The perceived costs of refusing to help when asked are likely to be higher in a face-to-face interaction, where the helper can be seen and potentially identified by the requester [26], and other work has shown that people are more cooperative in face-to-face interactions and/or when their name and picture are shown to others [26,30]. The difference we observe between the lost letter and the dropped item experiment helps to further quantify when and how direct requests might elicit help. Specifically, our study suggests that direct requests might increase helpful behaviour not because this reduces the diffusion of responsibility, but because a direct request increases the perceived reputation costs of refusing to help. This hypothesis could be explored in further experimental work.

We expected individuals in a group to help more than lone individuals as the presence of others would create the opportunity to accrue reputation benefits (e.g. [33,92,93]). However, in contrast with our expectations, we recorded higher helping from lone individuals than from individuals in groups in one of our experiments. One possibility is that individuals in social groups might be under greater perceptual load (e.g. in conversation with their acquaintance) which means that they do not note the helping opportunity. Another possibility is that people in groups experience greater perceived costs from pursuing an independent course of action (stopping to help an experimenter) that requires them to temporarily deviate from the group action, and also to impose the time costs associated with helping onto their acquaintance. We do not know of any study that addresses these latter possibilities empirically.

These results contribute to our understanding of the factors affecting variation in human cooperation. These data challenge the folk view that city dwellers are less cooperative than town dwellers and show that this variation may be a by-product of the association between urbanicity and deprivation. More generally, this study supports the hypothesis that deprivation reduces the willingness to extend impartial norms of cooperation towards strangers.

Gay men: Having older brothers, older sisters, & being an only-child increase in different amounts the probability of being gay

Reassessing the Effect of Older Sisters on Sexual Orientation in Men. Ray Blanchard & Richard A. Lippa. Archives of Sexual Behavior, Oct 6 2020.

Abstract: This research reanalyzed questionnaire data from 8279 homosexual and 79,519 heterosexual men who participated in 2005 in an internet-based research project sponsored by the British Broadcasting Corporation. It focused on parameters of sibship composition (older brothers, older sisters, younger siblings) previously shown or hypothesized to influence sexual orientation in males. The results included the usual finding that older brothers increase the odds of homosexuality in later-born males. As predicted, older sisters also increase those odds, although by a lesser amount than older brothers. Other results confirmed that the odds of homosexuality are increased in only-children, the amount of increase being equal to that produced by one older brother and greater than that produced by one older sister. Finally, the results indicated that younger siblings have no effect on the odds of homosexuality in males. These results might be explained by the hypothesis that two different types of immune responses in pregnant women can affect the future sexual orientation of their male fetuses. One type of response affects fetuses in first pregnancies and reduces subsequent fertility. The other type affects fetuses in later pregnancies and has little or no effect on fertility. Finally, we conducted an estimate of combined sibship effects. Men who were exposed to any of the influences that we identified (being an only-child or having an older sibling) had 27% greater odds of homosexuality than did subjects who were exposed to none of these influences (i.e., the first-born of two or more children).

References to high‐risk drinking persist during the pandemic despite restrictions on large social gatherings; more alcohol‐related blackout tweets were written between March 13th and April 24th in 2020 than 2019

Describing the impact of the COVID‐19 pandemic on alcohol‐induced blackout tweets. Rose Marie Ward  Benjamin C. Riordan  Jennifer E. Merrill  Jacques Raubenheimer. Drug and Alcohol Review, October 6 2020.

Rolf Degen's take:


Introduction and Aims: COVID‐19, considered a pandemic by the World Health Organization, overwhelmed hospitals in the USA. In parallel to the growing pandemic, alcohol sales grew in the USA, with people stockpiling alcohol. Alcohol‐induced blackouts are one particularly concerning consequence of heavy drinking, and the extent to which blackout prevalence may change in the context of a pandemic is unknown. The purpose of the current study is to describe the prevalence of publicly available tweets in the USA referencing alcohol‐induced blackouts prior to and during the COVID‐19 outbreak.

Design and Methods: We used Crimson Hexagon's ForSight tool to access all original English tweets written in the USA that referenced alcohol‐related blackouts in 2019 and 2020. Using infoveillance methods, we tracked changes in the number and proportion of tweets about blackouts.

Results: More alcohol‐related blackout tweets were written between 13 March and 24 April in 2020 than 2019. In addition, a greater proportion of all tweets referenced blackouts in 2020 than in 2019. In the period prior to the ‘stay at home’ orders (January to mid‐March), the proportion of blackout tweets were higher in 2020 than 2019.

Discussion and Conclusion: Our findings demonstrate that references to high‐risk drinking persist during the pandemic despite restrictions on large social gatherings. Given that the internet is a common source of information for COVID‐19, the frequent posting about blackouts during this period might normalise the behaviour. This is concerning because alcohol use increases susceptibility to COVID‐19, and alcohol‐related mortality can further tax hospital resources.


Our findings demonstrate that references to high‐risk drinking (i.e. blackouts) persist during the pandemic despite lack of access to venues where alcohol is commonly consumed and restrictions on large social gatherings. The continued trend of blackout mentions on Twitter during the pandemic is disconcerting due to the additional strain risky drinking may place on the health‐care system. Furthermore, the consistent pattern of blackout tweets during the month of March to April 2020 is surprising given that traditional college spring break activities, the ability to drink in typical venues (e.g. bars, restaurants) and social interactions were limited. In short, we expected a dip in the rate of blackout tweets due to these restrictions. Drinking to the point of blackout appears to be continuing, though may be occurring in different contexts. Given that over 94% of people in the USA were instructed to observe ‘stay at home orders’ [18], there may be people consuming at risky levels with potentially fewer people around them that can help them in an alcohol‐related emergency.

Furthermore, infoveillance [12] information such as that used here has the potential to provide insight into future alcohol problems in the USA. For example, exposure to 9/11 was linked to binge drinking rates 5–6 years later [19]. This indicates that experiences of mass stress (similar to a pandemic) increase later drinking rates. Similarly, with the 2003 SARS outbreak, hospital employees in China reported alcohol abuse/dependence symptoms 3 years later [20]. Moreover, research suggests that alcohol‐induced blackouts are a potential screener for additional alcohol‐related negative consequences [3]. Additionally, posts about alcohol on Twitter are linked to self‐reported drinking behaviours [21]. Therefore, while our data cannot speak to whether alcohol problems will increase in the future, using Twitter to monitor the impact of the pandemic on alcohol‐induced blackouts informs potential immediate needs (e.g. extra hospital resources or points of intervention) and may forecast potential lasting impacts of the pandemic (e.g. increased rates of alcohol misuse).

The limitations of the current study must be considered. Because the sample is limited to English language tweets, it is possible it might not generalise to individuals who do not post in English. Furthermore, the tweets were limited to public tweets in the United States, which excludes tweets kept private or where no user information exists to locate the tweet. A further limitation is that the US States did not announce their ‘stay at home’ and ‘shelter in place’ orders on exactly the same date and the adherence to those orders is unknown. However, the total window across all states was only 23 days, and the trends observed here extend beyond that range. More detailed analyses examining data for each state relative to their specific announcement date are beyond the scope of this publication, but may be of value.

Whereas tweets about blackouts are not a perfect measure of the extent of risky drinking in a population, our methods can provide insight into the extent of extreme drinking that persisted despite pandemic conditions (e.g. stay at home conditions; lack of traditional college spring break celebrations) and the extent to which drinking behaviour is changing in tandem with the pandemic. In addition, tweets provide information beyond traditional self‐report surveys. For example, the timing of the tweet (date, time of day), location and wording could provide information not only about past drinking experiences, but also about context and anticipation concerning future drinking experiences. Moreover, while it is yet to be seen, our findings suggest that there might be lasting impacts on alcohol consumption multiple years after the pandemic similar to the SARS outbreak [20] and 9/11 [19]. Our findings indicate that public health officials should consider monitoring behaviours presenting risk health such as alcohol‐related blackouts as they might be intensifying the effects of the pandemic.

A main conclusion of previous research on homogamy among romantic couples is that “matching partners are far from random”; this paper disagrees

Homogamy in Gender Role Attitudes Among Young Couples: Evidence from Germany. Ansgar Hudde. KZfSS Kölner Zeitschrift für Soziologie und Sozialpsychologie, Oct 6 2020.

Rolf Degen's take:

Abstract: Romantic partners’ similarity in gender role attitudes affects important outcomes such as sharing of housework, relationship stability, or fertility. However, there is little knowledge about how similar romantic partners are in these attitudes. Using dyadic panel data from German couples (sourced from pairfam), this study puts the degree of homogamy in gender role attitudes among young couples into perspective by comparing real couples with two types of counterfactuals. To create these counterfactuals, I re-mate couples in two ways: (a) randomly and (b) in such a way that similarity in attitudes between partners is maximized. Real couples differ only slightly from randomly mated couples, which suggests rather weak attitudinal similarity. Using longitudinal information, I further test the mechanisms that determine the degree of homogamy: there is strong evidence for alignment over time and for lower rates of separation among homogamous couples, but no evidence for homogamy as a by-product of assortative mating on other variables. This paper offers methodological and substantial contributions to the literature: it presents a method for intuitive assessment of the degree of homogamy with multiple variables simultaneously. It also shows that in Germany, macro-level diversity in attitudes largely translates into dissimilar attitudes between partners—with important implications for relationship dynamics.


A main conclusion of previous research on homogamy among romantic couples is that “matching partners are far from random” (Schwartz 2013, p. 452). This study puts the degree of homogamy in gender role attitudes among young couples into perspective and shows that, in fact, mating is not so far from random. The degree of homogamy is low to moderate. I test whether similarity in gender role attitudes is a by-product of assortative mating on education or religiosity and find very little evidence for such indirect assortative mating. This study finds clear evidence for alignment over time: fixed-effects panel models show that partners’ attitudes become substantially more similar over time. Further, partners with dissimilar attitudes are substantially more likely to separate.

These results strengthen our understanding of processes in partner selection. Among observed couples with an average relationship duration of 2.4 years, similarity in attitudes is moderate. Clear evidence for alignment suggests that the observed couples might have been more dissimilar at the beginning of the relationship. Evidence for differential separation further suggests that some of the dissimilar couples might not be observed anymore, because they have already separated. If we could observe couples on day 1 of their relationship, their similarity in attitudes would be substantially lower. Even though there are good reasons to choose a partner who has similar attitudes—it improves the odds of having high relationship satisfaction and stability—many young people in Germany do not. This could be because people have different priorities during the dating process, e.g. appearance, hobbies or social status, or because people just do not have sufficient information about the attitudes of the people to whom they are getting closer. From a practical perspective, this could be motivation to gather better information about the attitudes of a potential partner, e.g. through explicit discussion of gender roles and relevant scenarios.

Many studies on homogamy test whether homogamy is statistically significant, but do not provide an intuitive understanding of the degree of homogamy. Such studies show that real similarity is significantly higher than randomness would predict; however, they do not discuss how much more similar they are. This paper presents a novel methodical approach to doing exactly this: giving an understanding of the degree of homogamy. This contributes to social science research that focuses not only on statistical significance but on substantive meaning of observed differences and association (Bernardi et al. 2017). A main advantage of this method is that it allows the assessment of homogamy on multiple dimensions simultaneously. This method can help scholars in future studies on homogamy concerning diverse traits.

This study has limitations. The stated goal of our sample selection was to get very close to initial mating. Even though pairfam is the largest data set of young couples of which I am aware, the sample size becomes small when restricting the maximum duration of relationship to low levels. To produce a reasonable sample size, I analysed couples with an average relationship duration of around 2.4 years. The sample analysed underrepresents two groups. First, couples that do not live together. Previous research on the selectivity of partner participation in pairfam showed that partners living in a different household are less likely to participate. Therefore, couples with a lower degree of institutionalisation are underrepresented in the data. Second, I only studied childless couples. Therefore, this study is not representative of (the rather small group of) couples that become parents very early.

In sum, this paper shows that even though there are good reasons why people might want to choose a romantic partner who has similar gender role attitudes, many people do not. These results have important implications for relationship dynamics and macro-level patterns of fertility and union status. Previous research showed that the partners’ match in attitudes influences their relationship and sharing of housework, childcare and the partners’ approach to paid work (Nitsche and Grunow 2018). Further, couples with dissimilar attitudes have lower relationship satisfaction, relationship stability and fertility (Hohmann-Marriott 2006; Arránz Becker 2013; Hudde and Engelhardt 2020). At the aggregate level, couple dissimilarity can lead to higher rates of separation and divorce, and contribute to the overall low level of fertility in countries like Germany. To understand such macro-level outcomes, we need to understand the processes of partner selection.

Marginally significant: Boys might find solo play less rewarding than joint play, whereas girls find solo and joint play equally rewarding

Exploring the Benefits of Doll Play Through Neuroscience. Salim Hashmi, Ross E. Vanderwert, Hope A. Price & Sarah A. Gerson. Front. Hum. Neurosci., October 1 2020.

Abstract: It has long been hypothesized that pretend play is beneficial to social and cognitive development. However, there is little evidence regarding the neural regions that are active while children engage in pretend play. We examined the activation of prefrontal and posterior superior temporal sulcus (pSTS) regions using near-infrared spectroscopy while 42 4- to 8-year-old children freely played with dolls or tablet games with a social partner or by themselves. Social play activated right prefrontal regions more than solo play. Children engaged the pSTS during solo doll play but not during solo tablet play, suggesting they were rehearsing social cognitive skills more with dolls. These findings suggest social play utilizes multiple neural regions and highlight how doll play can achieve similar patterns of activation, even when children play by themselves. Doll play may provide a unique opportunity for children to practice social interactions important for developing social-emotional skills, such as empathy.


This is the first experiment to directly test the neural correlates of play in young children. We found that the pSTS, a brain region associated with social processing and empathy, is activated when children play with a social partner, regardless of whether that play is with dolls or a tablet. Interestingly, however, when playing alone, this region is more engaged during doll play than tablet play. This supports behavioral findings that pretend play supports social processing and empathic reasoning (Dunn and Cutting, 1999Brown et al., 2017) and raises new queries regarding the benefits of solo vs. social play.

That pSTS activity did not differ between play forms when children played with a social partner suggests that children can rehearse social perspective-taking and empathy when playing with a partner, regardless of whether that play takes the form of pretend play with dolls or creative play on a tablet. This is consistent with findings suggesting that screen-time is most beneficial for social and cognitive development when carried out interactively (e.g., Supanitayanon et al., 2020).

The interaction between social context and play type was driven by the fact that, when playing alone, there was more pSTS activity for a doll than tablet play. This provides support for Piaget’s (1962) classic claim that all pretend play is inherently social in that it allows the rehearsal of social interactions and social perspective taking (Harris, 2000). Pretend play with dolls therefore provides a unique outlet for practicing social and empathic skills even when playing by oneself.

There were no differences in terms of PFC activation, associated with executive functioning, between doll and tablet play. This implies that children did not recruit executive function skills differentially when playing with different toys. Although these findings contrast previous research finding associations between executive function and pretend play in preschool-aged children (e.g., Albertson and Shore, 2009Kelly and Hammond, 2011), they are in line with research findings in older children where these associations are not found (Hoffman and Russ, 2012). An interaction between the hemisphere and social context of play indicated that the right PFC was more activated during joint than solo play (but this was not the case for left PFC). This suggests that social play requires more behavioral control than solo play, but why this effect is specific to the right hemisphere is an open question.

In terms of reward processing, no difference in OFC activation was found between different forms of play, but a gender by social context interaction indicated that there was marginally less activation for boys than girls during solo play. This implies that boys might find solo play less rewarding than joint play, whereas girls find solo and joint play equally rewarding. This should be interpreted with caution, however, given that the post hoc tests were only marginally significant.

The findings from this experiment are unique in that they measured brain activity during live, natural play. The play was open-ended and no instructions were given to children except to play how they would like. The fact that the pSTS, a social processing region, was activated during open-ended play thus bolsters previous laboratory-based findings indicating that this region is important for social interactions, social processing, and empathy (Lloyd-Fox et al., 20092015Redcay et al., 2010Lahnakoski et al., 2012Deen et al., 2015Hakuno et al., 2018). Doll and tablet play sessions were designed such that both would allow free, creative play with no set goals or objectives. Although doll play is often categorized as an activity for girls rather than boys, we found no gender differences in brain activity when playing with either dolls or tablets. This suggests that the benefits of play are not unique to either gender.

These findings have implications for potential interventions. Previous research in 4- to 7-year-old children has found that a preference for playing alone in various play activities is associated with teachers’ ratings of the children’s behavior as asocial, experiencing peer exclusion, and is negatively associated with mother’s ratings of their social engagement (Coplan et al., 2014Ooi et al., 2018). Whilst it could be that children prefer to play alone because they experience peer exclusion, it could also be that those who prefer solitary play do not gain the advantage in social skills afforded by social play. If pretend play with dolls does help children practice these social skills without the threat of exclusion or rejection, this could be one avenue to improve social functioning in these children.

Although measuring brain activity during natural play has many advantages, it also limits the conclusions we can draw from the current findings. Whether particular brain activity reflects rehearsal of the skills typically associated with that region cannot be directly assessed in the current experiment. Future research should build on the current findings by assessing whether individual differences in brain activity related to variability in behavior that reflects practicing these skills (e.g., empathy, perspective-taking, and executive function), and whether there is a subsequent improvement in these skills.

This research provides the first evidence that social processing brain regions are similarly active during pretend play with dolls both when playing alone or with a social partner. The fact that pSTS activation is stronger for doll play than tablet play specifically when playing alone is consistent with the notion that pretend play allows children to practice social interactions even when playing by themselves. The implications of these findings for those interested in play, neuroscience, and social development are far-reaching and are suggestive that research investigating the short- and long-term consequences of pretend play on both brain and behavior will be fruitful.

Both men and women who played a violent game had significantly lower self-perceived performance, and as a result, reported a lower self-perceived mate value

Kasumovic, M. M., Hatcher, E., Blake, K. R., & Denson, T. F. (2020). Performance in video games affects self-perceived mate value and mate preferences. Evolutionary Behavioral Sciences, Oct 2020.

Abstract: Mate value is tied to appearance and age in women, and social status and wealth in men. Theory surrounding self-perceived mate value suggests that mate value shows relatively little situational plasticity. Here we challenge this concept by asking participants to compete in video games to test (a) whether self-perceived and actual performance affects subjective mate value, and (b) whether subjective mate value affects mate preferences. By randomly allocating participants to play either a violent or nonviolent game in three separate experiments, we show that both men and women who played a violent game had significantly lower self-perceived performance, and as a result, reported a lower self-perceived mate value. We also demonstrate that this effect led to different preferences for short-term mating partners, mainly among women. Our results strongly suggest that mate value in humans is situationally dynamic and responds to recent contest experiences, as it does in nonhumans. We discuss our results with reference to online multiplayer digital gaming experiences and how variation in self-perceived mate value affects mating market dynamics.