How Large Are Gender Differences in Toy Preferences? A Systematic Review and Meta-Analysis of Toy Preference Research

How Large Are Gender Differences in Toy Preferences? A Systematic Review and Meta-Analysis of Toy Preference Research. Jac T. M. Davis & Melissa Hines. Archives of Sexual Behavior, January 27 2020. https://link.springer.com/article/10.1007/s10508-019-01624-7

Abstract: It is generally recognized that there are gender-related differences in children’s toy preferences. However, the magnitude of these differences has not been firmly established. Furthermore, not all studies of gender-related toy preferences find significant gender differences. These inconsistent findings could result from using different toys or methods to measure toy preferences or from studying children of different ages. Our systematic review and meta-analysis combined 113 effect sizes from 75 studies to estimate the magnitude of gender-related differences in toy preferences. We also assessed the impact of using different toys or methods to assess these differences, as well as the effect of age on gender-related toy preferences. Boys preferred boy-related toys more than girls did, and girls preferred girl-related toys more than boys did. These differences were large (d ≥ 1.60). Girls also preferred toys that researchers classified as neutral more than boys did (d = 0.29). Preferences for gender-typical over gender-atypical toys were also large and significant (d ≥ 1.20), and girls and boys showed gender-related differences of similar magnitude. When only dolls and vehicles were considered, within-sex differences were even larger and of comparable size for boys and girls. Researchers sometimes misclassified toys, perhaps contributing to an apparent gender difference in preference for neutral toys. Forced choice methods produced larger gender-related differences than other methods, and gender-related differences increased with age.

Discussion

We found a broad consistency of results across the large body of research on children’s gender-related toy preferences: children showed large and reliable preferences for toys that were related to their own gender. Thus, according to our review, gender-related toy preferences may be considered a well-established finding. Our results, with 75 studies and a range of toy preference measurements, complement and extend a previous meta-analysis of 16 studies focused on free play (Todd et al., 2018).
However, our meta-analyses also revealed some gaps that could prevent confident inferences about the drivers and consequences of children’s gender-related toy preferences. These gaps could form priority targets for future research. Our analyses also revealed some emergent patterns in the data, especially in how gender-related preferences for broad groups of toys differed in some respects from those for dolls and vehicles, how study results varied according to study method, and how gender-related differences in toy preferences related to child age.

Toy Selection and Gender Categorization

The way that toys are selected, and categorized, as boy-related or girl-related, is not standardized in the present research. Studies in our review appeared to treat the gender categorization of toys as uncontroversial, even though, according to our review, it was not uncommon for toys to be assigned to different gender categories in different studies. For example, in some studies, blocks were classified as boy-related toys (e.g., Alexander & Saenz, 2012; Benenson et al., 1997; Fagot & Patterson, 1969), and in other studies they were classified as neutral toys (e.g., Cherney et al., 2003; Guinn, 1984; Wood, Desmarais, & Gugula, 2002). Similarly, drawing toys were sometimes categorized as girl-related toys (e.g., Berenbaum & Hines, 1992; Martin et al., 2013), and sometimes as neutral toys (e.g., Berenbaum & Snyder, 1995; Pasterski et al., 2005); and stuffed toys were equally likely to be classified as girl-related toys (e.g., DeLucia, 1963; Jacklin et al., 1973) as neutral toys (e.g., Alexander & Saenz, 2012; Idle et al., 1993; Moller & Serbin, 1996), but were also sometimes classified as boy-related toys (e.g., Stagnitti, Rodger, & Clarke, 1997). This pattern suggests that researchers sometimes disagree on what toys are boy-related, girl-related, or neutral.
In addition to finding that researchers sometimes disagreed on toy classifications, we also found that researchers typically did not report how they had selected toys for study or how they had assigned the toys to gender categories. We suspect that, in most cases, researchers used a simple heuristic method based on perceived cultural stereotypes. There are two problems with this type of approach. First, as noted above, toys categorized using this approach do not always fall into the same gender category in different studies. If one study includes a stuffed toy in the category “girls’ toys” and another study includes a stuffed toy in the category “neutral toys,” they may well report different results, even if the true underlying effect they are measuring is the same. Second, at its extreme, this problem may manifest as criterion contamination, in which gender-typed toys are defined by the results of the study. That is, the researchers may use many toys and select as “gender-related” toys the ones that they find to be differentially preferred by gender. At best, this tautology limits the generalizability of study results to other samples. At worst, it could invalidate the study.
Using methods that avoid confusion about toy categorization could be a priority for future research on children’s gender-related toy preferences. As also suggested by Fine (2015), this field could benefit from researchers specifying more clearly the ways in which they selected and categorized toys. Depending on the goal of the study, this selection and categorization might be based on different criteria. For example, a study examining whether stereotypes about children’s toy preferences relate to children’s actual preferences, might select toys based on adults’ independent ratings of the gender stereotyping of toys. In contrast, a study of the effect of a particular mechanism, such as social, cognitive, or hormonal influences, on toy preferences might select toys based on prior studies’ findings that certain toys are on average preferred by girls or boys. Overall, the important point is that researchers report more clearly how they selected toys and assigned toys to gender categories.
Researchers also have begun to investigate specific hypotheses about what characteristics of different toys might make them appeal more to boys or to girls. For instance, it has been suggested that color or shape might influence children’s gender-related preferences (e.g., Jadva et al., 2010; Weisgram et al., 2014; Wong & Hines, 2015). Similarly, it has been suggested that affordance of activity, motion, or propulsion might influence these preferences (Alexander & Hines, 2002; Benenson et al., 1997; Hassett et al., 2008; for a review, see Zosuls & Ruble, 2018). To evaluate these suggestions, it would be useful if researchers could provide color images, or full descriptions, of the toys used in the research they report. Similarly, it would be useful for this purpose, as well as for future reviews, if researchers could provide descriptive statistics, including means and SD or similar, by sex, for individual toys used, and not just for toy groupings.
To test whether the meta-analysis results were affected by researchers’ definitions of toy gender, we analyzed the subset of effect sizes that related to a very narrow definition of boy-related toys and girl-related toys: specifically, vehicles and dolls. These toys were the only ones for which sufficient data had been reported to allow reliable meta-analyses. The gender effects observed in the overall meta-analyses were broadly replicated with this more narrowly defined subset of toys, giving us confidence that our overall meta-analytic results were not entirely dependent on how researchers had chosen to categorize toys in regard to gender.
Furthermore, we found that girls’ gender-specific preference for dolls over vehicles was larger than their preference for broadly defined groups of girl-related toys. However, despite the large effect size, girls’ gender-specific preference for dolls over vehicles was not statistically significant, as this effect also showed large meta-analytic statistical variance. The large meta-analytic statistical variance is due to a combination of large variances in girls’ preference for dolls within the studies, variation between studies introducing additional statistical variance, and a smaller total number of studies that reported separate statistics for dolls as compared to broadly defined toy groups. In addition, the broadly defined toy groups included toys that, as mentioned above, were classified as neutral in some studies but girl-related in others. If toys are classified consistently, girls may show gender-related preferences at least as large as those of boys.

Culture and Gender-Related Toy Preferences

Cultural perceptions of play, including play with toys, may differ in different cultural, ethnic, or socioeconomic groups. For example, play is viewed as central to children’s cognitive and social development in many Western, technologically developed societies, but as less important in more traditional societies (Roopnarine, 2010). Children in different cultures may also have different referential concepts for appropriate gender-related behavior, due to cultural variation in gender norms (Pfeiffer & Butz, 2005; Wood & Eagly, 2002). This possibility is particularly relevant to toy preferences, because there may be cultural variations in the toys that are available, culturally relevant, and gender-related.
Nevertheless, little empirical research is presently available on cultural variation in gender-related toy preferences. Our review revealed that most toy preference studies focus on the U.S., Canada, the UK, and Australia. Of those studies conducted outside English-speaking industrialized nations, one was conducted in France (Le Maner-Idrissi, 1996), one in Finland (Lamminmäki et al., 2012), four in Sweden (Nelson, 2005; Nordenström, Servin, Bohlin, Larsson, & Wedell, 2002; Serbin et al., 2001; Servin, Bohlin, & Berlin, 1999), and one in the Netherlands (van de Beek et al., 2009). An additional study included some participants from Hungary, along with participants from the UK (Turner & Gervai, 1995). These studies did not report different results to the studies from the English-speaking countries, even when researchers had specifically hypothesized that they would (e.g., Nelson, 2005). In global perspective, however, these countries are very similar in terms of industrialization, wealth, education, media access, democracy, and gender equality. Consequently, children in these countries probably have very similar toys available to them and similar access to information about dominant social stereotypes around these toys. It remains an open question, then, whether children in cultures with radically different stereotype referents and social norms would show the same gender-related toy preferences to those found in the current meta-analysis.
We did not formally investigate other aspects of cultural diversity, such as ethnicity and socioeconomic status, because these also have not received much attention in empirical studies of gender-related toy preferences. Participants in most toy preference studies are not very ethnically diverse, and so it may not be practical to report results by ethnicity. We found three studies (out of our total 75) that reported toy preferences by ethnicity. Two of these studies were conducted in the USA and reported no significant differences in gender-related toy preferences between children of Hispanic and non-Hispanic background (Goble, 2012), or Native American and non-Native American background (Guinn, 1984). In contrast, another study based in the U.S. found that ethnicity might affect children’s preferences for gender-related activities, including play with toys, via children’s social networks (Martin et al., 2013). Furthermore, in recent years, the wider field of gender development research has paid increasing attention to the intersectionality of gender, ethnicity, and other identities (e.g., Shields, 2008). This trend in the wider field may translate in future to more studies investigating gender-related toy preferences in diverse social groups.

Methods of Measuring Toy Preference Are Important

Studies may find different gender effects on children’s toy preferences, depending on the method they use to measure toy preferences. We evaluated four categories of study methods: free play methods, where children were given access to a set of toys and observed playing, however, they liked; visual preference measures, where children were asked to look at pictures of toys; forced choice methods, where children were asked to choose toys or pictures of toys, typically in front of an experimenter; and naturalistic methods, where children’s toy options were not predefined by the researchers or other adults. We found that forced choice methods consistently showed larger gender differences than other methods.
There are two possible explanations for this pattern. One is the potential demand characteristics of forced choice paradigms. A request to publicly choose an option may be interpreted as evaluative by children, who then feel obliged to give the answer that they feel is “correct,” rather than indicate their actual preference. Children’s propensity to misunderstand requests for information as tests has been noted in other contexts (e.g., Lamb et al., 2003). Another possibility is that the paradigm creates a false dichotomy. In forced choice methods, the child is usually presented with one boy-related option and one girl-related option and asked to choose between them. There is usually not a neutral option, and, generally, the child must choose only one option and reject the other. In contrast, in a free play paradigm, children typically have more response options available, such as several toys associated with each gender, or neutral toys as well as gender-related toys. Even if only two toys are available, the child has more options than in most forced choice paradigms. For example, if a doll and a car are available, a child may choose to play with the doll, play with the car, play with both the doll and the car, or play with neither. In most forced choice methods, however, children must choose one and only one of two options.
Forced choice methods, in their current form, do not give comparable results to other methods of measuring gender-related toy preferences. Nevertheless, forced choice methods can be an efficient and easily administered measurement tool and therefore may be appropriate for studies where, for example, data need to be collected across a very large group or under difficult conditions. Future investigators wishing to measure gender-related toy preferences with an easily administered tool might do so, however, with the aim of minimizing artificial inflation in effect sizes. For instance, a procedure in which the experimenter cannot see which option the child selects, and the child knows that their response is not seen, might be useful. It also might be useful to include neutral options, as well as gender-related options, and allow the range of possible choices to include “both” or “neither.” These modifications of forced choice methods could provide results that are more comparable to other methods of measuring toy preference and perhaps are more reflective of children’s actual gender-related preferences.

Child Age and Gender-Related Toy Preferences

We found that gender differences in preferences for gender-related toys increased linearly with child age. Our results further suggested that this pattern could be explained by boys’ showing increased preference for gender-typical over gender-atypical toys with age, while girls’ preferences for gender-typical over gender-atypical toys did not increase significantly with age. Similarly, the previous meta-analysis of free play studies (Todd et al., 2018) found an increase in gender-related play with age in boys, although they did not find increasing gender differences. This may reflect a difference in the power of the two meta-analyses; the previous meta-analysis included 16 studies, whereas the current meta-analysis included 75 studies. We did not find significant curvilinear effects of age on children’s gender-related toy preferences.
Our findings of linear effects contrast with those of some prior investigations of age effects on children’s gender-related toy preferences. For example, Campbell et al. (2000) measured infants’ gender-related visual preferences longitudinally at ages 3, 9, and 18 months. They found that preferences did not change with age, but the infants were all very young compared to the age range in the wider literature and in the current meta-analysis.
In contrast, our meta-analytic findings suggest that boys’ and girls’ gender-related toy preferences increase with age in a linear fashion. These findings resemble findings for a broader measure of children’s gender-typical behavior, the Pre-School Activities Inventory (PSAI). The PSAI is a 24-item parent report inventory that asks about children’s gender-typed toy preferences and about children’s gender-related activity and playmate preferences. A longitudinal, population study in which the PSAI was completed by a parent to describe their child at ages 2, 3, and 5 years also found that both boys and girls became increasingly gender-typed with age (Golombok et al., 2008).
Our results suggest that children’s toy preferences might become more gender-related with age, as predicted by several theories of gender development. Children might be encouraged, through socialization pressures such as modeling and reinforcement, to prefer same gender-related toys, and the effects of this socialization may accumulate as they get older (Fagot, Rodgers, & Leinbach, 2000). Additionally, based on their early gender-related toy interests, children might gravitate to different social environments, enhancing their early preferences (Liben & Bigler, 2002; Martin et al., 2013). Finally, differences in children’s prenatal and early postnatal hormone exposure may dynamically interact with social environments and cognitive processes to increase children’s gender-related preferences over time (Hines, 2012). Together, these social and cognitive effects, and their interactions with early hormonal influences, may explain the linear increase in gender-related differences with age.
The findings of our meta-analysis, however, are not a substitute for a large, longitudinal study of children’s gender-related toy preferences. We used meta-analytic techniques to compare gender-related preferences in children from different age groups, reported in different studies. Our analysis, therefore, was cross-sectional and does not have the inferential power of a well-controlled longitudinal study. Our results would be best confirmed by a future longitudinal study of children’s gender-related toy preferences from infancy to pre-pubertal age. The longitudinal parent report study using the PSAI (Golombok et al., 2008) is the closest existing example and found similar results to our meta-analysis.

Gender-Related Toy Preferences Over Time

We found no change in the magnitude of gender-related differences in toy preferences across year of publication. The results of the moderator analyses suggested that gender effects on children’s toy preferences have remained generally constant in magnitude across the past five decades. This finding might seem surprising. Since the earliest studies on gender-related toy preferences, gender-atypical behavior and preferences have become increasingly socially acceptable. Perhaps the lack of any discernible pattern of change results from different social pressures influencing gender-related toy preferences in different directions. For example, growing acceptance of gender-atypical behavior may be countered by increasing gender segregation of the toy market.
Contrary to our results, a previous meta-analysis of children’s toy preferences (Todd et al., 2018) found that boys and girls played more with gender-related toys in earlier studies than in more recent studies. Todd et al. suggested that increasing gender equality in Western societies could influence children to play with neutral toys, due to increased advertising to children about gender-neutral toys. A recent analysis of online toy marketing, however, found that more toys were marketed for “boys only” or for “girls only” than for both (Auster & Mansbach, 2012), and an analysis of department store catalogs concluded that gender differentiation in toy advertising had increased since the 1980s as marketers employed gender stereotypes to encourage sales (Sweet, 2013). Taken together, these analyses challenge the view that gender-related toy advertising is decreasing with time. Alternatively, the previous finding could be partly explained by the smaller time frame considered in the prior meta-analytic review; the prior review covered about 35 years of research, while the present review covered 50 years.
It may be that children’s preferences are robust to social influences at this macrolevel; or that, despite social change, the underlying cultural environment regarding gendered toys has not changed. A similar result was found in a systematic review of gender stereotypes from the 1970s to the present. Rudman and Glick (2008) hypothesized that women’s changing social roles would be reflected in changing stereotypes of women. Although they found a change in women’s self-concept over time, they also found that more general stereotypes of women’s personalities had not changed. They suggested that the lack of change might be due to people viewing personality as part of the fundamental essence of gender, and therefore being reluctant to modify their stereotypic beliefs about personality. A similar explanation may also apply to toy preferences: if people view toy preferences as an essential part of a child’s gender, they may be unlikely to change their gender-related beliefs about toy preferences. Children may then adapt their actual toy preferences to reflect broader societal beliefs.

Limitations

The meta-analysis could only include data that were reported in the individual toy preference studies. Therefore, we could not analyze variables such as color or shape, or individual toys other than dolls and vehicles. In future research, if investigators report more information about toy characteristics and about individual toys, it may be possible to discover more about what characteristics of different toys make them more likely to be preferred by one gender or another.
Our literature search covers papers published to March 2014 and does not include papers published outside of this time frame. More recent papers may therefore be missing from the current meta-analysis. The current meta-analysis, however, synthesizes 50 years of research on toy preferences and finds that toy preference effect sizes have not changed significantly over time. Thus, results from a new review including more recent papers would be unlikely to differ from what we report.
We focused on gender-related preferences in typically developing children. Some studies selected participants specifically because they were not typically developing (for example, clinical samples of children with genetic variants causing atypical early hormone environments, or children who showed gender-related behavior that was noticeably different from their peers). To include these atypical populations in our study might have skewed the results, so we did not include them. Our results, therefore, may not apply to clinical populations.
Additionally, we meta-analyzed only direct measures of children’s toy preferences. We did not, for example, include parent report measures. Similarly, we did not include broader aspects of children’s gender-related behavior, such as activity preferences, playmate preferences, or sex role identification (e.g., Brown, 1956). Additionally, we did not search for these broader terms, so we may have missed papers that included toy preferences in a broader measure of sex role identification or androgyny (e.g., Zucker & Torkos, 1989). It would be interesting to know whether meta-analyses from these other sources of data and types of gender-related behavior would show similar outcomes. We hope that the current systematic review and meta-analysis will encourage such studies.

Intact microbiota is a key component of older males attractiveness; age-based preferences may break down when the microbiota is impaired, like when individuals are exposed to naturally occurring antibiotics, extreme temperatures

Drosophila Sexual Attractiveness in Older Males Is Mediated by Their Microbiota. Chloe Heys et al. Microorganisms 2020, 8(2), 168. Jan 22 2020. https://doi.org/10.3390/microorganisms8020168

Abstract: Age is well known to be a basis for female preference of males. However, the mechanisms underlying age-based choices are not well understood, with several competing theories and little consensus. The idea that the microbiota can affect host mate choice is gaining traction, and in this study we examine whether the male microbiota influences female preference for older individuals in the fruit fly Drosophila pseudoobscura. We find that an intact microbiota is a key component of attractiveness in older males. However, we found no evidence that this decrease in older male attractiveness was simply due to impaired microbiota generally reducing male quality. Instead, we suggest that the microbiota underlies an honest signal used by females to assess male age, and that impaired microbiota disrupt this signal. This suggests that age-based preferences may break down in environments where the microbiota is impaired, for example when individuals are exposed to naturally occurring antibiotics, extreme temperatures, or in animals reared in laboratories on antibiotic supplemented diet.

Keywords: age; Drosophila pseudoobscura; female choice; indirect benefits

The Mismeasure of Genes: No Support for the Genetic Hypothesis of the Black-white Achievement Gap Using Polygenic Scores and Tests for Divergent Selection

Bird, Kevin A. 2020. “The Mismeasure of Genes: No Support for the Genetic Hypothesis of the Black-white Achievement Gap Using Polygenic Scores and Tests for Divergent Selection.” SocArXiv. January 27. doi:10.31235/osf.io/2qfkt

Abstract: Protracted debates about the cause of an observed IQ gap between Black and white populations around the world have persisted within the fields of genetics, anthropology, and psychology for over a century. Newly available public genomic data have changed each of these fields in many ways; one side effect is that they have encouraged a new generation of race science. The current generation of race scientists claims that analysis of polygenic scores---generally computed as linear combinations of alleles identified by a genome-wide association study---provide evidence that a significant portion of differences in cognitive ability between Black and white people are caused by genetic differences, frequently claiming these differences came about due to divergent natural selection. In light of recent calls for cautious interpretation of polygenic-score analyses by geneticists, I apply the latest robust methods to detect genetic differentiation and polygenic selection that address known biases in polygenic-score analysis, testing the claim that genetic differences explains the gap in educational attainment and cognitive performance and that divergent selection has occurred between African and European populations. I show that past results were inflated by these biases and a more careful analysis provides strong evidence inconsistent with divergent selection and genetic differences driving the Black-white gap in cognitive ability.

Fever dreams were more bizarre & more negatively toned & included more references to health & temperature perception compared to normal dreams – findings that are in line with the continuity hypothesis of dreaming

Fever Dreams: An Online Study. Michael Schredl and Daniel Erlacher. Front. Psychol., January 28 2020. https://doi.org/10.3389/fpsyg.2020.00053

Abstract: In addition to a large variety of somatic symptoms, fever also affects cognition, sleep, and mood. In an online survey with 164 participants, 100 fever dream reports were submitted. Fever dreams were more bizarre and more negatively toned and included more references to health and temperature perception compared to “normal” most recent dreams – findings that are in line with the continuity hypothesis of dreaming. Future studies should follow up this line of research by conducting diary studies during naturally occurring febrile illnesses and sleep laboratory studies with experimentally induced fever. It would also be very interesting to study the effect of thermal stimulation applied during sleep on dream content. This research helps to understand subjective experiences while sleeping in an extreme condition (elevated body temperature).

Discussion

The present study indicates that fever affects dreaming; fever dreams are more bizarre – confirming the previous finding of our pilot study (Schredl et al., 2016b) in an independent sample – but also included more negative dream emotions, less dream characters and interactions, and more health-related topics and heat perceptions than the matched normal non-fever dreams. As fever dreams have not yet been studied systematically, it is reassuring that we were able to replicate the pilot findings with a new independent sample indicating that the present findings are substantial.

Before discussing the findings, several methodological issues will be addressed. First, fever dreams were elicited retrospectively, i.e., sometimes experienced quite some time ago. That might have biased the results as extraordinary dreams are more likely to be recalled after such long periods of time (Cipolli et al., 1992). However, the time interval between occurrence of the dream and its reporting was not related to emotional intensity or bizarreness. In addition, the dreams selected for comparison were also retrospectively recalled dreams. In order to test for possible recall effects using retrospective designs, it would be very interesting to use a prospective approach like Smith (2012b), i.e., hand out a dream diary and instruct the participants to complete this diary if they suffer from a febrile illness. However, one has to keep in mind that fever does not occur that often, so this study might be arduous. The retrospective nature of the study also does not allow any inferences regarding the sleep stage in which the dreams occurred. As fever can trigger episodes of sleepwalking (Avidan, 2017), one might speculate if, for example, the first dream example is a remembrance of a sleepwalking episode. Typically reports from NREM parasomnia episodes can include the bed chamber but are very brief (Arnulf, 2019), so the finding that fever dreams are generally comparable in length and even more bizarre than “normal” dreams indicates that those reports rarely reflect sleepwalking. However, content of sleepwalking episodes related to fever has never been studied systematically; the subjective experiences within these episodes might also be more bizarre compared to “normal” sleepwalking episodes. Due to the rare occurrence of fever episodes, ambulatory polysomnographic studies, i.e., recording the sleep stage prior to the reported dream, are very arduous. It would also be very interesting to study the effect of experimentally increasing body temperature by cytokines (cf. Reichenberg et al., 2001) on dream characteristics and content. Next, it should be noted that the sample consisted of high dream recallers; the mean dream recall frequency in the general population is about one morning per week with dream recall (Schredl, 2008) whereas in our study the mean dream recall frequency indicated dream recall several times a week. On the other hand, reporting a fever dream was not related to dream recall frequency but to the frequency of having fever. But one might argue that the reported percentages of experiencing fever dreams while being ill is an overestimation in this study due to overall heightened dream recall and, therefore, it would be necessary to carry out surveys in representative samples for obtaining data as to how often fever dreams occur.

The finding that fever dreams contain more intense negative emotions and less intense positive emotions supports the continuity hypothesis of dreaming as fever is also accompanied by more negative moods in waking (Reichenberg et al., 2001) and negatively toned dreams might reflect these negative waking emotions. This link between waking emotional tone and dream emotions has been shown in healthy persons (Schredl and Reinhard, 2009-2010). Also, Bódizs et al. (2008) found that poor health is related to more negatively toned dreams. To follow up this line of thinking, future studies could elicit mood during waking in persons with fever and test how strong waking emotions affect dreams while being ill. Similarly, it would be interesting to test whether the cognitive impairment in waking due to fever (Hall and Smith, 1996; Smith, 2012a) is directly related to dream bizarreness, i.e., are dreams of persons with more pronounced cognitive impairments more bizarre than dreams of persons with mild cognitive impairments during a febrile illness? The basic idea is that the “over-heated” brain is not functioning properly and, therefore, dreams are more bizarre. In schizophrenic patients, for example, the severity of psychotic symptoms during the day is directly related to dream bizarreness (Schredl and Engelhardt, 2001).

Also in line with the continuity hypothesis is the finding that fever dreams included more health-related topics. A previous study in patients with insomnia (Schredl et al., 1998b) showed that more health problems are associated with more health-related dreams. Interestingly, the frequency of health-related dreams is not only related to the frequency of the illnesses but also to worrying about health (Schredl et al., 2016a), i.e., future studies might also include this variable.

Interestingly, the findings of less dream characters and less physical and verbal Interactions also fit in the continuity hypothesis because one of the accompanying behavioral changes of fever is social withdrawal (Harden et al., 2015).

Lastly, fever dreams included more references to temperature perception (see the illustrative second dream example) than non-fever dreams. In a long dream series, explicit temperature perceptions were present in only in 0.63% of the dreams (Schredl, 2016). This increased number of temperature perceptions in fever dreams might reflect the waking-life experience of feeling hot, within the framework of the continuity hypothesis, but it is also plausible that the fever dreams might be affected by the internal sensation of feeling hot while sleeping. Research has shown that external stimuli like sounds, water spray, rocking of the bed, and mild pain stimuli are sometimes incorporated into dreams (Dement and Wolpert, 1958; Nielsen et al., 1993; Leslie and Ogilvie, 1996). Interestingly, somatosensory stimulation of the leg muscles was incorporated into dreams quite often and could result in bizarreness related to the body image (Nielsen, 1993); the dream examples might also reflect a very creative processing of the internal heat stimulus. However, studies on the effect on dreams of thermal stimulation, e.g., thermal stimuli applied to the skin, have not yet been performed. If heat stimuli are incorporated into dreams, the hypothesis that fever directly affects dreams via the increased body temperature would be supported.

To summarize, this study showed that fever dreams are quite common and differ significantly from non-fever dreams, i.e., fever dreams were more bizarre, more negatively toned and included more references to health and temperature perception. Future studies should follow up this line of research by conducting diary studies during naturally occurring febrile illnesses and sleep laboratory studies with experimentally induced fever. This research helps to understand subjective experiences while sleeping in an extreme condition.

Sub-par embryos are terminated automatically; embryos improve test performance by exaggerating formerly honest quality signals; new honest indicators arise while old degraded indicators linger

Embryo Selection and Mate Choice: Can ‘Honest Signals’ Be Trusted? Dakota E. McCoy, David Haig. Trends in Ecology & Evolution, January 28 2020. https://doi.org/10.1016/j.tree.2019.12.002

Highlights
.    Mate choice by honest signaling is a classic explanation for elaborate traits in nature. Many researchers have: (i) observed deceptive signaling, and (ii) wondered how honest signals relate to trait elaboration.
.    Honest signaling is analogous to high-stakes testing. Quality is hard to measure directly, so proxies (tests) are used. High-stakes testing causes ‘teaching to the test’ without improving educational outcomes.
.    Embryo choice is another high-stakes test. Mothers select healthy embryos and terminate sub-par embryos automatically. Embryos are selected to pass maternal tests without improving their quality. The resulting arms race causes extreme and elaborate signals during pregnancy.
.    We can better understand elaborate traits in nature if we interpret mate selection, and embryo choice, as a dynamic give-and-take between two parties with conflicting fitness interests.

Abstract: When a measure becomes a target, it often ceases to be a good measure – an effect familiar from the declining usefulness of standardized testing in schools. This economic principle also applies to mate choice and, perhaps surprisingly, pregnancy. Just as females screen potential mates under many metrics, human mothers unconsciously screen embryos for quality. ‘Examinees’ are under intense selection to improve test performance by exaggerating formerly ‘honest’ signals of quality. Examiners must change their screening criteria to maintain useful information (but cannot abandon old criteria unilaterally). By the resulting ‘proxy treadmill’, new honest indicators arise while old degraded indicators linger, resulting in trait elaboration and exaggeration. Hormone signals during pregnancy show extreme evolutionary escalation (akin to elaborate mating displays).

The major purpose that episodic counterfactual thinking serves is mood regulation: to daydream and to feel better

Branch, Jared. 2020. “Involuntary Mental Time Travel into the Episodic Future, Episodic Past, and Episodic Counterfactual Past in Everyday Life.” PsyArXiv. January 27. doi:10.31234/osf.io/jbkfg

Abstract: To date, studies exploring episodic counterfactual thoughts have employed laboratory studies to discern the subjective qualities of voluntary mental time travel (Branch & Anderson, 2018; De Brigard & Giovanello, 2012; Özbek, Bohn, & Berntsen, 2017). Here, we offer the first diary study of episodic counterfactual thinking, and therefore we report the subjective qualities of involuntary mental time travel into the counterfactual past. We find that such thoughts do occur, although to a much lesser extent than mental time travel into the future or past (i.e. episodic future thinking or episodic memory). The major purpose that episodic counterfactual thinking serves is mood regulation: to daydream and to feel better. We observed that the majority of episodic counterfactual thoughts are experienced in the recent past and decrease as a function of time. We also report on the phenomenological aspects of episodic counterfactual thoughts as they relate to future thinking and memories.

Affective polarization (steady growth of the mutual dislike between Republicans and Democrats): Elites in the US have polarized faster than those in eight other OECD countries of study

Cross-Country Trends in Affective Polarization. Levi Boxell, Matthew Gentzkow, Jesse M. Shapiro. NBER Working Paper No. 26669, January 2020. https://www.nber.org/papers/w26669

Abstract: We measure trends in affective polarization in nine OECD countries over the past four decades. The US experienced the largest increase in polarization over this period. Three countries experienced a smaller increase in polarization. Five countries experienced a decrease in polarization. These findings are most consistent with explanations of polarization based on changes (e.g., changing party composition, growing racial divisions, the emergence of partisan cable news) that are more distinctive to the US, and less consistent with explanations based on changes (e.g., the emergence of the internet, rising economic inequality) that are more universal.

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4.2 Evaluation of Potential Explanations

Figure 3 plots average trends in each explanatory variable separately for the groups of countries

with rising or falling affective polarization. Appendix Figure 6 plots the individual series for each of the explanatory variables that we consider.

Internet and broadband penetration increased in all countries over the sample period, yet affective polarization did not. This is inconsistent with implication (i). Moreover, internet penetration appears to have risen faster in countries with falling polarization. This is inconsistent with implication (ii). The fact that in many countries polarization rose faster in the post-2000 period than the pre-2000 period is consistent with a role for digital media, but digital media cannot account for the rapid growth in affective polarization in the US and Canada during the 1990s. (See also Boxell et al. 2017.)

Income inequality, as measured by the Gini coefficient, increased in all sample countries except Switzerland, for which we have limited data. This is inconsistent with implication (i). Moreover, the data do not exhibit evidence of implication (ii).

Openness to trade, as measured by the trade share of GDP, likewise increased fairly broadly over the sample period, with no clear evidence of a faster increase in those countries with increasing affective polarization.

All countries experienced an increase in the foreign-born share of the population over the period for which we have data, and differences in the rate of growth do not appear to align with differences in the trends in affective polarization.

In our view, the data do not support the hypothesis that these factors played an important role in the rise in affective polarization in the US in the sense of equations (1) and (2).

Other explanations are more consistent with our data. The period we study saw important changes in the composition of the political parties in the US. Among both political elites and voters, party identification became increasingly aligned with both political ideology and social identities such as race and religion (McCarty et al. 2008; Abramowitz and Saunders 2008; Levendusky 2009; Fiorina 2016, 2017; Mason and Wronski 2018; Valentino and Zhirkov 2017).6 Many scholars have identified such “party sorting” among voters as a key potential cause of affective polarization, with sorting leading those from opposite parties to differ more on average in both ideology and identity (Iyengar et al. 2019; Mason 2016, 2018; Fiorina and Abrams 2008; Webster and Abramowitz 2017). The underlying drivers of party sorting are not fully understood, and sorting could be a consequence as well as a cause of affective polarization (Lelkes 2018). However, many drivers emphasized in the literature, such as the realignment of the parties in the South following the civil rights era, are distinctive to the US and originate at least in part in the strategic choices of political elites rather than the shifting views of voters themselves (Fiorina and Abrams 2008, p. 581; Levendusky 2009, 2010; Lupu 2015; Banda and Cluverius 2018).7

Consistent with the view that changing party composition is distinctive to the US, Rehm and Reilly (2010) find that, according to expert ratings of party positions, elites in the US have polarized faster than those in the eight other OECD countries we consider. Some of these countries (e.g., Canada) have experienced smaller increases in polarization among political elites, and some (e.g., Australia, Norway, Sweden, Germany, and the UK) have experienced declines in elite polarization. Consistent with the hypothesized mechanism, Canada has also experienced growing partisan differences in issue positions among voters (Kevins and Soroka 2018), whereas Britain and Germany have experienced overall declines (Adams et al. 2012a; Munzert and Bauer 2013). Fiorina’s (2017, Chapter 8) review of this and related evidence likewise concludes that the US has experienced faster growth in elite polarization and party differences in issue positions among voters than countries in Western Europe.

Increased party sorting by race has also been highlighted as a potentially important driver of affective polarization (see, e.g., Valentino and Zhirkov 2017; Abramowitz 2018; Mason and Wronski 2018; Westwood and Peterson 2019). Such sorting may in turn be driven by the growth in the non white share of the population. With the caveat that it is difficult to define and compare racial composition across countries and time periods (see Appendix A.6), it is noteworthy that the increase in the non-white share has been twice as large in countries with rising affective polarization as in those with falling affective polarization (see Figure 3).

The rise of 24-hour partisan cable news provides another potential explanation. Partisan cable networks emerged during the period we study and arguably played a much larger role in the US than elsewhere, though this may be in part a consequence rather than a cause of growing affective polarization. The timing of the introduction of Fox News appears roughly consistent with the acceleration of the growth in affective polarization during the 1990s, as well as with the observation that older demographic groups both consume more partisan cable news and have polarized more quickly than younger demographic groups in the US (Boxell et al. 2017; Martin and Yurukoglu 2017). Interestingly, the five countries with a negative linear slope for affective polarization all devote more public funds per capita to public service broadcast media than three of the countries with a positive slope (Benson and Powers 2011, Table 1; see also Benson et al. 2017).

Check also Merkley, Eric, and Dominik Stecula. 2020. “Party Cues in the News: Democratic Elites, Republican Backlash and the Dynamics of Climate Skepticism.”  British Journal of Political Science. Preprint January 25. https://www.bipartisanalliance.com/2020/01/supporters-of-republican-party-have.html

Metal music fans exhibit moral reasoning styles dependent on their metal sub-genre identification; the moral reasoning styles explain partially lyrical preferences that weren’t already explained by personality

Morality in everything, chapter 23958:

The role of moral reasoning & personality in explaining lyrical preferences. Kyle J. Messick, Blanca E. Aranda. PLoS One, January 24, 2020. https://doi.org/10.1371/journal.pone.0228057

Abstract: Previous research has supported that personality traits can act to a precursor to media preferences. Due to the ongoing association between morality and media preferences in public and political discourse (e.g., blaming immoral behaviours on media preferences), this research sought to expand the knowledge about factors that contribute to media preferences by investigating if moral reasoning styles explain some of the variance that was not already explained by personality traits. A specific form of media preferences were chosen – lyrical preferences in metal music – as claims between metal lyrical themes and behaviour have been ongoing since the 1980s, despite a lack of empirical evidence to support these claims. A lyrical preferences scale was developed, and utilizing this scale, it was found that different types of metal fans exhibit different moral reasoning styles dependent on their metal sub-genre identification. Further, it was found that moral reasoning styles explain a portion of the variance in lyrical preferences that weren’t already explained by personality traits. In particular, lyrical preferences were often thematically consistent with moral reasoning content and personality traits, such as that individuals that preferred lyrics about celebrating metal culture and unity had higher levels of the group loyalty moral reasoning domain alongside being higher in extraversion. The implications of moral reasoning styles and personality traits as being precursors to media preferences are discussed.

Discussion

This study examined the association between lyrical preferences, moral reasoning domains, and personality traits. We first developed a lyrical preferences scale that allowed for comparisons between members of the metal music community. We then identified differences about moral reasoning based on the type of metal preference (e.g., black metal fans had the lowest scores on the sanctity/degradation moral foundation), and further analyses revealed a rather nuanced understanding about how lyrical preferences are related to moral foundations.

Correlations showed that enjoying lyrics about depression, hardships, love, and emotional turmoil (i.e. human experience) are related to having higher scores on the care/harm and fairness moral domains, which suggests that those people who prefer these lyrics might find the struggles of others related to their own hardships, and might be more empathetic to those struggles. Individuals who showed a preference for vulgar lyrics, such as misogyny, violence, and Satanism in their lyrical content, have significantly lower scores on the sanctity/degradation moral domain compared to other metal fans. One possible explanation is that these metal music fans have a different understanding of sanctity (e.g., thinking of the body as a temple), which is materialised in how these music fans with vulgar/immoral lyrical preferences have higher levels of extreme and unusual piercings and body modifications than metal fans with other lyrical preferences (something we recorded in this study, but was not a focus of the analysis). It is also possible that those who prefer more disgusting lyrics are approaching the idea of disgust in a fundamentally different way than most other music and metal music fans. Adding further cause for concern, the sanctity/degradation subscale has recently been questioned for how inconsistently it applies to people who are not religious [64], which is primarily the case for metal fans in the current sample, as most participants identified themselves as atheistic, agnostic, or ‘none.’ This moral domain has been further criticized, as it has been claimed that ‘purity’ is a descriptive label, and does not reflect a form of moral processing [65]. Future research could explore the relationship between the sanctity of the body and the self for metal fans, particularly for those that prefer immoral/vulgar lyrics.

A preference for lyrics about embracing metal culture & fun, which include themes like unification and loyalty, was associated with higher scores on the moral domains for authority/subversion, group loyalty, care/harm, and sanctity/degradation. It is expected that lyrics about loyalty would be associated with higher levels of loyalty as a moral foundation, which would extend into the authority moral domain, since this shows an appreciation of leadership and followship, as well as a respect for traditions. These lyrics celebrate metal culture, which might extend to a more formal view of metal culture, via respect for traditions, loyalty to the metal community, increased levels of caring, and more common views on purity compared to those who prefer vulgar/immoral lyrics and more extreme metal subgenres. This is a direction that future research could further explore. Lyrics about honour and pride include sentiments that fit well into a worldview that has structure and respect for that structure.

A preference for lyrics about history, mythology, and nature, which include lyrics about war, patriotism, and martyrdom, was positively associated with the group loyalty moral foundation. This association is reasonable, as lyrics about war can emphasize themes such as loyalty to a nation, regime, or historical entity, so individuals who enjoy these are likely seek out lyrics about loyalty as this is a moral principle important to them.

Having a preference for lyrics about science and science fiction only had a relationship with the care/harm moral domain. These are likely lyrics that are more morally neutral, which might explain the lack of an association with other moral domains. The association between science and science fiction lyrics and the moral foundation that focuses on empathy and struggle is not an intuitive one, so future research could explore this relationship by encompassing preferences for this sort of content in other forms of media, such as science fiction films.

Personality traits also had a relationship with lyrical preferences, including vulgar/immoral lyrical preferences negatively relating to agreeableness. People that enjoyed lyrics about embracing metal culture and fun had personality traits that reflected being more extraverted and agreeable, so this lyrical style that embraces activities with groups and friends is consistent with being outgoing, sympathetic, and trusting of others. Preferring lyrics about the human experience was positively related to being more agreeable, neurotic, and open to experience, showing that choosing to listen to emotional lyrics about human experiences is often consistent with having a personality associated with feelings like anxiety, depression, and loneliness. In other words, there was consistency between the lyrical subject matter and the emotional experiences of the person. Similarly, choosing to listen to lyrics about history, nature, and mythology was associated with higher levels of neuroticism and openness to experience. Lastly, enjoying lyrics about science & science fiction were only related to higher levels of openness to experience. Openness to experience is likely associated with lyrics about history and science fiction because these are lyrical topics that describe experiences that might be far from the user’s everyday experiences, indicating a preference towards lyrics that have interesting and often unfamiliar narratives that satiates their openness and desire for new experiences.

These relationships were given further clarification by investigating the extent to which moral reasoning and personality traits explained lyrical preferences. It was found that moral foundations do explain a unique and significant portion of the variance in lyrical preferences that was not already accounted for by personality traits. For example, preferring lyrics about human struggle was related to the moral foundation for care in addition to higher levels of neuroticism and agreeableness. In this instance, an individual that has higher levels of care and empathy involved in how they morally reason might also prefer lyrics about human emotions and struggles that similarly use their ability to be empathetic, since some of their personality traits (neuroticism) suggest that a tendency towards emotional instability.

In relation to the insights from moral panic theory, this study clarifies the direction between moral reasoning and lyrical preferences adding support to the hypothesis that lyrical preference reflect pre-existing moral foundations and personality traits, rather than lyrics leading to a ‘corruption’ of morality. This is consistent with previous findings showing that those who perform acts of violence seek out lyrics that justify their pre-existing beliefs about violence [4].

This study has also brought insights to the metal studies literature, showing that adhering to a metal subgenre has significant implication. For example, black metal fans had lower levels in the sanctity/purity moral domain, which is consistent with the frequently anti-religious message of black metal culture [66].

A few limitations should be noted. First, the moral foundations subscales had slightly lower internal reliabilities than anticipated. It is worth nothing that recently, Moral Foundations Theory (MFT) has been criticized for how difficult it is to replicate across cultures [67]. These limitations might extend into metal culture, in which case MFT might not be the ideal way to explore the moral reasoning of people within metal music culture. Further, the lyrical factor scale developed here comes with its own limitations. It is not expected that the factors presented would be universal across every music culture since lyrical themes and meanings vary across cultural contexts. Although the different types of lyrics could be used in the study of other music cultures, it is likely that the factor structure of the scale would be different. For instance, gang-related activities fall under the vulgar/immoral factor for metal fans, but they might not fall into the same factor in hip hop music, since lyrical topics like Satanism (also part of the vulgar/immoral factor) probably don’t appeal to the same types of hip hop fans as gang-related lyrics. A future study could investigate the degree to which lyrics are interpreted as entertaining, relational, or as a statement of endorsement towards a certain perspective (e.g., pro-violence). This meaning-making approach to lyrics would allow for understanding the role and functions of lyrical preferences, with some functional possibilities including escapism, coping, or feeling like someone else understands a user’s emotional turmoil. Other future studies could evaluate how behaviour directly relates to moral reasoning and media preferences, since it is known that moral foundations don’t always correlate with moral behaviours [68]. Whereas it is the case that violent media, such as video games [28, 29], can reduce violent behaviours, a future study could see if listening to music with violent lyrical themes serves a similar function.

This study, which explored the relationship between lyrical preferences, moral preferences and personality traits will hopefully add more nuance to the discussion of types of music and their association with moral and immoral behaviours. We suggest that lyrical preferences might originate in pre-existing characteristics, including moral reasoning styles and personality traits. This evidence can be added to that of other precursors for media preferences, including emotional vulnerability/relatability [1], personality factors [2, 3], and pre-existing ideology [4]. Given this, it is hoped that future associations between media (not limited to metal music), and behaviour will take into account these psychological factors, since there is now evidence that moral orientation is as similarly fundamental as personality traits in predicting media preferences.

Risk attitude was an important reason why certain women did not alter their fertility after the collapse of Communism in 1989; this preference for risk could explain their children criminal propensity

Chevalier, Arnaud and Marie, Olivier, Risky Moms, Risky Kids? Fertility and Crime after the Fall of the Wall (December 2019). CEPR Discussion Paper No. DP14251, https://ssrn.com/abstract=3518590

Abstract: We study the link between parental selection and child criminality. Following the collapse of the communist regime in 1989, the number of births halved in East Germany. These cohorts became markedly more likely to be arrested as they grew up in reunified Germany. This is observed for both genders and all offence types. We highlight risk attitude as an important reason why certain women did not alter their fertility decisions during this time of economic uncertainty. We also show that this preference for risk was then strongly transmitted to their children which may in turn explain their high criminal propensity.

Keywords: crime, economic uncertainty, Fertility, parental selection, risk attitude
JEL Classification: J13, K42

All the Dark Triad & Some of the Big Five Traits Are Visible in the Face: Inferring personality from faces without any concrete source of information could be an evolutionarily adaptive trait

Alper, Sinan, Fatih Bayrak, and Onurcan Yilmaz. 2020. “All the Dark Triad and Some of the Big Five Traits Are Visible in the Face.” PsyArXiv. January 27. doi:10.31234/osf.io/c3ngz

Abstract: Some of the recent studies suggested that people can make accurate inferences about the level of the Big Five and the Dark Triad personality traits in strangers by only looking at their faces. However, later findings provided only partial support and the evidence is mixed regarding which traits can be accurately inferred from faces. In the current research, to provide further evidence on whether the Big Five and the Dark Triad traits are visible in the face, we report three studies, two of which were preregistered, conducted on both WEIRD (the US American) and non-WEIRD (Turkish) samples (N = 880). The participants in both US American and Turkish samples were successful in predicting all Dark Triad personality traits by looking at a stranger’s face. However, there were mixed results regarding the Big Five traits. An aggregate analysis of the combined dataset demonstrated that extraversion (only female), agreeableness, and conscientiousness were accurately inferred by the participants in addition to the Dark Triad traits. Overall, the results suggest that inferring personality from faces without any concrete source of information would be an evolutionarily adaptive trait.

Supplementary materials: https://osf.io/dbxe5/?view_only=2540de9ebdcf448cbf564efb1c721a43

46% of subjects choose to ignore calorie information, motivated by optimal expectations – subjects choose strategic ignorance so that they can downplay the probability of their preferred meal being high-calorie

Strategic ignorance of health risk: its causes and policy consequences. Jonas Nordstrom et al. Behavioural Public Policy, January 27 2020. https://doi.org/10.1017/bpp.2019.52

Abstract: We examine the causes and policy implications of strategic (willful) ignorance of risk as an excuse to over-engage in risky health behavior. In an experiment on Copenhagen adults, we allow subjects to choose whether to learn the calorie content of a meal before consuming it and then measure their subsequent calorie intake. Consistent with previous studies, we find strong evidence of strategic ignorance: 46% of subjects choose to ignore calorie information, and these subjects subsequently consume more calories on average than they would have had they been informed. While previous studies have focused on self-control as the motivating factor for strategic ignorance of calorie information, we find that ignorance in our study is instead motivated by optimal expectations – subjects choose ignorance so that they can downplay the probability of their preferred meal being high-calorie. We discuss how the motivation matters to policy. Further, we find that the prevalence of strategic ignorance largely negates the effects of calorie information provision: on average, subjects who have the option to ignore calorie information consume the same number of calories as subjects who are provided no information.

Rats: The curse of the yo-yo effect ("weight cycling"), rapid weight gains after a diet, fails to materialize

Effects of multiple cycles of weight loss and regain on the body weight regulatory system in rats. Jennifer L. Rosenbaum, R. Scott Frayo, Susan J. Melhorn, David E. Cummings, and Ellen A. Schur. American Journal of Physiology-Endocrinology and Metabolism, Oct 24 2019. https://doi.org/10.1152/ajpendo.00110.2019

Abstract: We studied the effects of multiple cycles of weight loss and regain on the defended body weight in rats. Thirty-six male Wistar rats were divided into three weight-matched groups: weight cyclers (n = 18), ad libitum-fed controls (n = 9), and maturity controls (n = 9). Cyclers underwent four rounds of 20% weight loss from 50% caloric restriction, each cycle followed by recovery to stable plateau weight on ad libitum feeding. Controls ate ad libitum. Maturity controls ate ad libitum and then weight cycled the final two rounds to evaluate the effect of age in later cycles. Cyclers’ postdiet plateau weight became progressively lower than that of controls. With each weight loss, ghrelin increased, while insulin and leptin decreased; the magnitude of these changes did not differ across cycles. After four rounds, cyclers’ weight (504 ± 7 vs. 540 ± 22 g; P < 0.05) and percent body fat (11.7 vs. 15.2%; P < 0.05) were lower than in controls. After a 4-mo follow-up period of ad libitum feeding, cyclers maintained a lower total fat-pad mass versus controls (8.6 ± 0.5 vs. 15.9 ± 3.6 g; P < 0.01) and a lower glucose area-under-the-curve on oral glucose tolerance tests (P < 0.05). Repeated weight-loss cycles exerted positive effects, durably lowering defended levels of body adiposity and improving glucose tolerance.