Thursday, March 28, 2019

A Comparative Approach to Morphological, Behavioral and Neurophysiological Aspects of Sexual Signaling in Women and Nonhuman Primate Females

Sexual Attractiveness: a Comparative Approach to Morphological, Behavioral and Neurophysiological Aspects of Sexual Signaling in Women and Nonhuman Primate Females. Bernard Wallner et al. Adaptive Human Behavior and Physiology, March 28 2019. https://link.springer.com/article/10.1007/s40750-019-00111-6

Abstract
Objective and Methods: This review focuses on comparative data in nonhuman primates and humans in relation to signaling secondary sex characteristics (SSC), sexual behavior, and neurophysiology of sexuality during the female cycle.

Results: In monkeys and apes no clear distinction can be drawn between sex as a reproductive, social, or a pleasurable activity. Although female sexual behavior is not limited to a specific phase of the menstrual cycle, changes in body morphology and in behavior and psychology (for example, in feeding, risk taking, and mood) can occur across the cycle. In human and nonhuman primates, homologous biological mechanisms including specific areas of the brain, sex steroids, and receptors are involved in regulating female sexuality. Important aspects of this regulation include the interaction between the subcortical reward system and the social brain network and its projection to the prefrontal cortex. In humans, females advertise SSC permanently after the onset of puberty, but without significant changes across the cycle, whereas in other primate species, female sexual signaling can vary significantly across cycle stages and in fertile and non-fertile phases of the life cycle.

Conclusion: A great deal is now known about the regulation of female sexuality in primates and the use of sexual signals in terms of their variable expression and their information content for males. Human research has also elucidated the cultural mechanisms through which women communicate about their sexuality, including clothes and make-up. A full understanding of female sexuality in humans, therefore, requires knowledge of culture-biology interactions.

Keywords: Comparative primatology Sexual attractiveness Neurophysiological organization Behavior

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Introduction

Female ovarian cycles have been thoroughly studied in many species of mammals. A great deal of research on endocrine mechanisms in relation to behavioral expression rates throughout different cycle stages has elucidated both the proximate regulation and the functional significance of female sexual and reproductive strategies in mammals. Female sexuality involves complex interactions between neuroendocrine mechanisms in relation to neurotransmitter activities to modulate behavior. Such neurophysiological processes are only partially understood in primates.
In most mammals, sexual activities are limited to the periovulatory period of the female cycle. This period is characterized by elevated estrogen concentrations leading to ovulation, followed by an increase of progesterone secretion that facilitates the implantation of the egg into the uterus. In general, sexual activity is correlated with estrogen increase and is reduced at elevated progesterone levels. The period of the cycle in which females are sexually receptive and sexually active is termed estrus.
The best-investigated female sexual behavior in terms of physiology and neurobiology is the lordosis reflex in rodents. This is a posture in which females allow male intromission. Shortly before ovulation, males approach their mating partners and mount them. This sensory interaction enables the lordosis reflex, which is controlled by the sex steroids estradiol and progesterone. The behavioral aspect of this reflex is regulated by subcortical hypothalamic brain structures such as the ventromedial nucleus and the periacqueductal gray, where ovarian hormones find acting sites to facilitate the reflex (Flanagan-Cato ; Uphouse ). The regulation of lordosis behavior involves complex neurobiological circuits and their underlying neurochemistry. As illustrated by Beach (), females advertise their sexual readiness to males with their attractiveness, followed by proceptivity (behavioral signals to males such as solicitation to copulate), and then by receptivity to copulatory behavior with subsequent ejaculation.
These three aspects of female sexuality are related to hormonal changes during the female cycle and ultimately serve the process of reproduction. The Beach paradigm was thought to encompass more or less all non-primate mammalian species. In primates, instead, it has long been known that females do not limit their sexual behavior to specific cycle stages and to the corresponding hormone fluctuations (Dixson ). In humans in particular, copulations can occur during all cycle stages (Dixson ). This has led some to believe that human sexuality is completely emancipated from its biological regulation and entirely dependent on volitional and cultural factors. It is, however, very unlikely that humans continued to evolved by natural selection up to the Pleistocene, but then suddenly stopped after settling and farming (approx. 10,000 years ago). Rather, it is more likely that cultural and genetic processes mutually interacted throughout all human evolution (Richerson et al. ). Natural selection is still acting on certain traits in contemporary humans (Byars et al. ) and producing adaptations through culture-gene co-evolution. This process may operate much more quickly than previously thought (Field et al. ). Although there are some important differences between human female sexuality and female sexuality in nonhuman animals, the prevalent view emphasizes continuity rather discontinuity between humans and other animals, especially other primates. Therefore, in this article, we highlight the many similarities between humans and nonhuman primates in hormone secretions, neurophysiological subcortical organization, and female sexual behavior during the reproductive cycle, with particular emphasis on the signaling of Secondary Sexual Characteristics (SSC).

Hormones, Behavior and SSC

In nonhuman primates, similar to other mammals, during the female’s cycle, sex steroid hormones are regulated by the release of the pituitary gland peptides follicle-stimulating hormone (FSH) and luteinizing hormone (LH). FSH stimulates the growth of the sex cells, the ovarian follicles; LH in high concentrations induces ovulation in Graafian follicles that have been primed with FSH. Data on rhesus macaques show that preovulatory LH and FSH peaks affect estradiol increases and thus represent important prerequisites for a successful ovulation (Dixson ). More than 40 years ago, Dixson et al. () reported not only a periovulatory increase of estradiol in primates, but also a similar peak of the androgen testosterone. Later, Nadler et al. () demonstrated an association between estradiol and testosterone concentrations during the mid-cycle phase and maximum perineal swelling size in the common chimpanzee. Moreover, the mid-cycle estradiol and testosterone peaks in chimpanzees are comparable to those in women (Morris et al. ).

The Three-Fold Impact of SSC in Nonhuman Primates: Attractiveness, Fertility, and Sociality

Females of many nonhuman primate species exhibit sexually attractive signals during their cycle. The most prominent signals are coloration and/or perineal swelling. The coloration and degree of anogenital swelling size may affect the vulva area, the clitoris, to some extent the perineal region, and the area around the ischial callosities (Dixson ). Both coloration and perineal swelling can vary dramatically among females in a group. Their expression rates are controlled by the sex steroids estradiol and progesterone. Estradiol enlarges swellings by transferring water into the intercellular tissue, and an increased blood flow causes more intensive coloration (Bradley and Mundy ). After ovulation, the luteal steroid progesterone reduces the swellings (Wildt et al. ). Both the intensity of coloration and the size of the swelling are most pronounced during the periovulatory period (Wallner et al. ; Möhle et al. ).
These periods are correlated with the highest copulation frequencies, and the probability of fertilization is highest as well. Nonetheless, studies on Barbary macaques indicate that sexual interactions are not limited to the periovulatory period and are therefore displayed independently of the probability of fertilization, e.g., pregnant females with perineal swellings can copulate as much as non-pregnant ones (Küster and Paul ). However, fluctuations in swelling size and/or coloration are often correlated with low sex hormone secretion rates and with sexual behavior. Lactating females too can show sexual solicitation behavior and copulations (Brauch et al. ). A comparison between non-lactating and lactating females in Japanese macaques revealed more intensive red coloration and copulations (with and without ejaculations) for non-lactating females during sexually active periods (Wallner et al. ). However, copulations (with and without male ejaculation) were not uncommon among lactating females, although they showed slight changes in coloration intensity and their sex steroid production was significantly lower compared to non-lactating females. Less well-understood is the functional significance of changes in coloration intensity and size of the perineal swellings in Tibetan macaques, as females in this species do not exhibit any typical behavior associated with estrus and they copulate frequently outside the mating season (when SSC are not obviously expressed) (Li et al. , ). Non-reproductive copulations were not observed in pregnant or lactating individuals and typically involved adolescent males. Such copulations often occurred after social conflicts, whereby females approached males and solicited copulation, suggesting a social function of sexual behavior (Li et al. ).
Ovariectomy does not suppress female sexual behavior in Old and New World monkeys. In stumptail (Baum et al. ) and rhesus macaques (Chambers and Phoenix ) ovariectomized females show some sexual receptivity, and in the common marmoset (Kendrick and Dixson ) males still exhibit high copulation frequencies with ovariectomized females. Baboon females that had been ovariectomized hardly drew the attention of singly housed males when placed in visual, olfactory, and auditory contact with them (Girolami and Bielert ). Nonetheless, if the same females were provided with large artificial swellings, then the males became sexually aroused and masturbated.
Masturbation is not unique to humans (Dixson ), but self-stimulation of genitalia is nearly exclusively reported in Old World monkeys and apes (Dubuc et al. ). This type of behavior is shown under captive, semi-free, and wild conditions. Barbary macaque females implanted with contraceptives exhibit perineal swellings during non-sexual periods. Males seemed to be more attracted to females with enlarged swellings (Wallner et al. ). They inspected — sniffed and touched — the anogenital region of these females and masturbated frequently in their presence. Almost no mounting behavior was performed, suggesting that visible sexual traits stimulate self-directed sexual behavior in males (Wallner, pers. obs.).
A study on same-sex mounting behavior in Japanese macaque females showed that females were able to self-stimulate their vulvar, perineal and anal (VPA) regions. Females also mounted other females and while doing so, they rubbed their VPA on their partners or stroked their VPA with their own tail (Vasey and Duckworth ). Because the VPA region mediates sexual arousal in both humans and in nonhuman primates, the authors of this study interpreted the behavior of macaque females as providing an immediate sexual reward. Such sexual sensation from genitalia activates the mesolimbic brain areas (Georgiadis and Kringelbach ), resulting in the perception of pleasure. Early research suggested that nonhuman primates mate exclusively in a dorso-ventral position, whereas humans prefer face-to-face sexual intercourse to facilitate female orgasm. Early studies also suggested that that nonhuman primate females are not able to experience orgasm. Both suggestions proved wrong: lesser and great apes engage in face-to-face copulation, and female orgasm has been recently reported in a number of monkey species (Dixson ).
Bonobos display unique patterns of socio-sexual behavior for nonhuman primates. In bonobos, sexual interactions occur daily, and independent of female cycle stages and therefore of reproduction. Sexual interactions involve a variety of sexual behaviors and include individuals of all age and sex combinations (Manson et al. ). Chimpanzees also exhibit perineal swellings beyond ovulation periods. Wallen and Zehr () noted, “The system of hormonally modulated sexual motivation combined with a physical capacity to mate at any time has evolved in primates to balance the social and reproductive uses of sex.” This clearly applies to female sexuality in great apes such as bonobos and chimpanzees. In orangutans, females do not express SSC, suggesting that ovulation is concealed (Pawlowski ). Knott et al. () investigated sexual interactions in Bornean orangutans. Near ovulation, females copulated with dominant, flanged males with large cheek pads, but during cycle stages with low probability of fertilization, females preferred less dominant, unflanged males. The authors suggested that in a species with concealed ovulation where males use frequent sexual coercion, such female sexual strategies may minimize male aggression. Differentiated female preferences for mating with adult and adolescent males at different cycle stages was also reported in Phayre’s leaf monkeys. During periovulatory periods (POP), females were more proceptive and receptive to adult males, but they preferred adolescent males during non-periovulatory periods (NPOP). Interestingly, adult males seemed to recognize female fertility better than adolescent individuals did (Lu et al. ). Another study investigated female chimpanzee mating preferences during POP and NPOP. Female proceptivity correlated with male mating success and female resistance behavior reduced male mating success, during POP. Proceptivity was also positively related with male mating success during NPOP. These data indicate the influence of female choice on male mating success during different cycle stages in chimpanzees (Stumpf and Boesch ). In white-handed gibbons, cycling females showed increased group-leading activities compared to pregnant or lactating females. The behavior probably served a non-ecological function, and helped females search for potential mating partners (Barelli et al. ).
Female SSC-related signals are attractive to males and may stimulate male sexual arousal. Females, in turn, may benefit from received increased social and sexual attention from males. For example, Barbary macaque females implanted with contraceptives can develop enlarged swellings during non-reproductive periods and, if so, they have more affiliative interactions and fewer agonistic interactions with males, and they receive more agonistic aid and more grooming from males (Wallner et al. , ). Similarly, female chimpanzees with swellings enjoy significantly more social benefits than those without swellings. In addition to their increased affiliative interactions with males, they gain greater access to food resources. Pregnant chimpanzee females with large perineal swellings may find it easier to transfer from one group to another without being attacked by males (Wallis , ). Furthermore, baboon males strategically approach swollen females when entering a new group (Goodall ), and affiliate temporarily with them.
Why males find SSC signals attractive is more difficult to interpret. In other words, the information content, if any, of these signals remains unclear. Pagel () argued that large perineal swellings are reliable indicators of female reproductive quality and health. Such signals must be the evolutionary result of intra-sexual female competition for males. This reliable indicator hypothesis was supported by data from wild olive baboons, showing that females that exhibited larger swellings during their sexually active periods had more affiliative interactions with males and produced more offspring than females with smaller swellings (Domb and Pagel ). Critics of this study, however, were able to show major flaws in the statistical data analyses. Subsequent studies failed to replicate these results and to show better reproductive performance for females with larger swellings (Setchell et al. ; see Fitzpatrick et al. ). Nevertheless, there are indications that conceptive swellings are larger than non-conceptive ones and that males do prefer to mate with females during those cycles with higher chance of fertilization (Fitzpatrick et al. ).
With regard to coloration, non-lactating Japanese macaque females had more intense red coloration, especially at the nipple and hindquarter regions, and all of them conceived during the sexually active period compared to those who were lactating (Wallner et al. ). In mandrills, multiparous females had brighter faces, possibly signaling their history of successful reproduction and current fertility, than nulliparous females (Setchell et al. ). Rhesus macaque males preferred females with more reddened hindquarters, whereas females paid more attention to faces of males and females with intense red coloration; the latter may be associated with female-female competition as well (Gerald et al. ; Dubuc et al. ). Similarly, Japanese macaque males were more interested in faces with more intense red coloration, and especially in faces with increased color contrast (Pflüger et al. ).
Female SSC signals in relation to ovulation are generally prominent in primate species that live in multi-male, multi-female groups with promiscuous mating systems. In contrast, in species that live in one-male units, with polygynous or monogamous mating systems, SSC signals such as sexual swellings are rare and seem to be less related to advertising female fertility. The ultimate reason for such differences seems to be intrasexual competition for mating partners during periovulatory periods in promiscuous species compared to one-male units [...exception is the white-handed gibbon...].

Women: Behavioral and Morphological Variation

Women’s sexual behavior may fluctuate significantly during their cycle. Burleson et al. () investigated allosexual and autosexual behavior in heterosexual and lesbian women with or without a partner. Allosexual behavior increased during the follicular and ovulatory phases in women living with a partner compared to those without a partner. In contrast, the frequencies of autosexual behavior were elevated during the follicular and ovulatory cycle phases in both heterosexual and lesbian women living without a partner vs those with a partner. A longitudinal study of female sexual behavior during five cycle phases - namely menstrual, postmenstrual, ovulatory, luteal and premenstrual - showed peak sexual activities during ovulation (Harvey ). That study used temperature charts to identify different cycle stages. A more recent investigation assessed sexual activities in relation to the preovulatory LH increase. Women initiated more sexual activities during the preovulatory LH surge and showed increased sexual desire and fantasies 3 days earlier (Bullivant et al. ). Pillsworth et al. () showed that sexual desire in paired women was mainly expressed during the periovulatory phase, and that among these women increased conception probability was correlated with sexual desire. Interestingly, the duration of partnership was positively related to sexual desire in extra-pair-relationships during periods of increased fertility. Another study on sexual fantasies in relation to menstrual cycle phases in single-living women showed increased sexual fantasies during preovulatory elevated LH secretion; these fantasies decreased after ovulation (Dawson et al. ). During follicular and periovulatory periods the number of sexual fantasies increased while emotional content increased in conjunction with ovulation (Dawson et al. ).
It has been argued that during fertile cycle phases, paired women may engage in short-term extra-pair relationships to mate with partners of high genetic quality (such as high testosterone levels, masculinity, dominance, symmetry) (e.g., Gangestad and Thornhill ). Two recent meta-analyses of these studies, however, provided mixed support this conclusion (Gildersleeve et al. ; Wood et al. ) and subsequent, rigorous investigations have failed to replicate some of the initial findings (Jones et al. , ; Jünger et al. ). Evidence concerning the influence of hormones on sexual desire during different cycle stages seems to be also conflicting. Roney and Simmons () found a significant negative correlation between progesterone increases and women’s desire for their partner and other men. In contrast, mid-cycle stages were related to high extra-pair and in-pair desire, although the correlation between desire and estradiol was only marginally significant. Contrary to these results, another study showed that higher estradiol levels are associated with an increased extra-pair sexual interest, whereas higher progesterone concentrations predict greater in-pair interest (Grebe et al. ). Finally, recent studies have provided some further conflicting evidence as to whether changes in estradiol and progesterone concentrations across the cycle are associated with changes in female general sexual desire vs female desire for particular types of sexual relationships (Jones et al. ; Shirazi et al. ).
Many studies of women’s mate preferences in relation to the menstrual cycle compare fertile vs luteal phases. During fertile periods, women do generally prefer masculine men who are assertive and competitive, have lower voices, or scents associated with body symmetry (Gangestad et al. ; Garver-Apgar et al. ). For example, in one study, women’s preference for male scents related to symmetric body features was positively related to women’s estrogen and testosterone levels, but negatively to their progesterone (Garver-Apgar et al. ). Furthermore, women with lower urinary estrone-3-glucuronide concentrations showed stronger cyclic shifts (non-fertile/fertile) in their preferences for masculine voices (Feinberg et al. ; but see Jünger et al. for negative results). Finally, cycle stage apparently plays an important role in being motivated to detect erotic stimuli in art. During the first half of the menstrual cycle, women emphasized more erotic stimuli in paintings compared to the second half of the cycle (Rudski et al. ).
Aside from behavioral changes, different energetic needs are also evident during the menstrual cycle. Lissner et al. () described two peaks of energy intake during the cycle: the first at the middle of the follicular phase, and the second at the middle of the luteal phase. Especially during the luteal phase, women crave more carbohydrate- and fat-containing food (Davidsen et al. ). From a physiological point of view, such food consumption behavior is relevant because energy is needed to produce the endocrine surges necessary for ovulation and for the successful implantation of fertilized eggs into the uterus tissue. Another study showed that consuming sweet food and its preference rating increase during the pre-ovulatory phase (Bowen and Grunberg ). Both, nonhuman primates and humans, however, show increased luteal energy intake compared to follicular phases (Dye and Blundell ). Czaja and Goy () carried out classical studies on food intake under estrogen and progesterone treatment in rhesus macaques and guinea pigs. In both species, the food intake decreased around the time of ovulation and increased during other cyclic periods. Estrogen administration to ovariectomized females showed a clear downregulation of feeding behavior. Ovariectomized females, however, did not change their feeding behavior after progesterone administration compared with control individuals in both species. Most recently, Roney and Simmons () tested hormonal predictors of daily self-reported food intake in naturally cycling women. They reported that estradiol negatively and progesterone positively predicted food intake, and that a decrease in eating during the fertile phase of the cycle was mediated by the two hormones. These associations between hormones and food intake were mirror images of those found for sexual desire, and were very similar to those reported in nonhuman primates.
In addition to sexual desire/preferences and food intake, a great deal of research has documented also changes in mood and cognitive function in relation to the menstrual cycle. Some of this research has involved estrogen replacement therapy (reviewed by Shively and Bethea ; see also Voytko , for data in female macaques). In women, the premenstrual syndrome and its association with depression are relatively well investigated (e.g., Forrester-Knauss et al. ). Interestingly, Shively et al. () were able to relate lower ovarian function and impaired HPA activity with signs of depression in subordinate macaque females.

Risky Behavior During Menstrual Cycle

Sexual interactions are per se related to physical risks for both sexes (Wallen and Zehr ). For example, T lymphatic viruses are sexually transmitted in humans and in several species of nonhuman primates (see Junglen et al. ). Simian and human immunodeficiency viruses (SIV, HIV) are among the most infamous sexually transmitted diseases. The Center for Disease Control and Prevention (https://www.cdc.gov/) has indicated that in the U.S. individuals between 15 and 24 years of age represent 27% of the sexually active population, yet they account for 50% of sexually transmitted infections. In their fact sheet of infections, gonorrhea ranks number one (70%) followed by chlamydia (63%), HPV (49%), genital herpes (45%), HIV (26%), and syphilis (20%). These data, however, do not reveal whether infections are related to specific menstrual cycle stages. Regarding the type of infection, women in the 15–24 years range seem to be most vulnerable to chlamydia infections. Interestingly, some of these pathogens - such as chlamydia (Chlamydia trachomatis) or syphilis (Treponema pallidum) – have also been detected in captive apes (Rushmore et al. ), although little research on sexually transmitted diseases has been conducted in wild nonhuman primates.
Molecular immune defense genes seem to evolve faster in promiscuous primate species, and especially in species that live in larger groups (Wlasiuk and Nachman ). Nunn et al. () found that white blood cell counts were significantly higher in primate species in which females have more mating partners, and therefore the risk of sexually transmitted diseases is higher. A recent study analyzed the evolution of the seminal protein gene semenogelin 2 (SEMG2) in primates, which is responsible for the semen coagulation rate (Dorus et al. ). The results showed that promiscuous species exhibit higher rates of SEMG2 polymorphism, which results in faster coagulation rates. The species with the highest evolution rate is the common chimpanzee. Interestingly, the relationship between the rate of evolution of SEMG2 and residual testis size is higher in humans than in polygynous (orangutan, gorilla) or monogamous (gibbon) species (Dorus et al. ). A similar correlation is evident between midpiece sperm volume (the location of mitochondria) and residual testis size in humans (Anderson and Dixson ). Both results indicate a selection process favoring moderate promiscuity in humans. Based on these findings and the previously mentioned female desire for extra-pair sex during fertile cycle stages, it may be argued that women’s fertility periods are associated with risky behavior.
In female baboons, an increased risk of injury (presumably related to reproductive competition) has been documented during days with a high conception probability (Archie et al. ). Promiscuous female baboons signal their periovulatory period with exaggerated swellings, which may attract the males’ sexual attention but also aggression from males and females. Women seem to have developed strategies to reduce their exposure to risk during fertile cycle periods. During ovulation, women engage in less risky behaviors to avoid sexual assaults (Bröder and Hohmann ) and show an increase in handgrip strength in response to a sexual assault vignette, suggesting the existence of behavioral adaptations to reduce the probability of conception as a result of rape (Petralia and Gallup ). However, strong individual differences probably exist among women in their tendency to engage in sex-related risky behavior in relation to their age, personality, chronotype (i.e., morningness-eveningness), and hormonal profiles (e.g. Maestripieri ). It is possible that variation in female risky behavior during the cycle may be influenced by cortisol and its interaction with sex hormones. A study on a rural Mayan population showed increased urinary cortisol during the follicular phase and between day 4 and 10 after ovulation. Interestingly, higher cortisol during the follicular phase was associated with progestin concentrations, suggesting an impairment of implantation processes (Nepomnaschy et al. ).

Women’s Advertising During Different Cycle Phases

Do human females differ from other primate females in advertising their sexual attractiveness in relation to different cycle stages? In contrast to some primate SSC signals such as exaggerated sexual swellings, which fluctuate across the cycle in relation to changes in estrogen and progesterone concentrations (Wallner et al. , ), women have permanent developed SSC such as the waist-to-hip ratio, buttocks, and breasts. Nonetheless, cyclic changes in body morphology are evident also in women (reviewed in Farage et al. ). Most of these changes are related to physiological parameters such as lipid content of skin, collagen production, pigmentation, hydration, thermoregulation, functional aspects of the immune system or changes of water compartments and subcutaneous fat tissue. Whether these cyclic modifications are detectable by men remains unclear (Puts et al. ; for evidence, instead, that cyclic modifications in faces are detectable by women, see Necka et al. , ; Hurst et al. ; Krems et al. ).
Some of the most obvious changes occur in the subcutaneous fat regions of the thighs and abdomen (Perin et al. ). In these areas, fat increases up to 4% during menstruation, and the fat content is lowest during the first half (follicular stage) of the cycle. Fowler et al. () used magnetic resonance imaging to detect changes in the female breast volume during the cycle. During the period between day 16 and 28, which more or less corresponds to the luteal phase, the water content increased by 24%, and parenchymal volume by 38%. In comparison, during menstruation, water content decreased by 17%, and parenchymal volume by 30%. This represents a major volume change for the breast tissue, which is analogous to changes in anogenital swellings in nonhuman primates. However, the volume increase in swellings is mediated by estrogens and is based on a shift of intracellular water into the interstitial tissue, whereas the volume increase in the breast tissue seems to be mediated by luteal progesterone. Whether these subcutaneous fat changes during the cycle are temporal SSC, which signal attractiveness in women remains unclear.
There are, however, hints that women try to enhance their sexual attractiveness during particular phases of the cycle. A study on more than 300 women revealed some associations between clothing preferences, sexual motivation, and hormone concentrations (Grammer et al. ). Higher sexual motivation was associated with the tendency to wear sheer clothing (which allows the woman’s body or undergarments to be seen through its fabric), whereas salivary estradiol concentrations were correlated with the amount of skin exposure and with clothing tightness. Moreover, women significantly change their consumer behavior across the cycle and spend more time and money on cosmetics, fashion, and jewelry during the periovulatory phase (Durante and Griskevicius ; Durante et al. ). There is also some evidence that these changes in behavior are influenced by hormones and that they reflect female-female competition for mating partners (Durante and Griskevicius ; Durante et al. ).
These findings indicate that women are aware of their cycle stage and use their clothes or make-up to attract men’s attention on particular body regions such as their lips, breasts, or hips (see Haselton and Gildersleeve ). Gait also changes during the cycle, such that particular postures are used that help advertise SSC such as the waist and hips. Guéguen showed that during the periovulatory phase women walk more slowly and that men find this sexier, suggesting that gait is a critical behavior used by women to display and enhance their physical attractiveness. Wearing shoes with high heels may influence the walking performance of women during periovulatory cycle stages. Wearing high heels enables women to change significantly the lumbar curvature and the inclination of the pelvis (Smith ). Visually, this yields a posture signaling a hollow-back and exposing the waist and hips more prominently. Evidently, men recognize it as a supernormal stimulus and associate it with female attractiveness. High heels also influence the gait of women by reducing stride length and increasing the rotation of the hip.
In conclusion, advertising physical attractiveness is an important adaptive trait in the context of sexual interactions in many nonhuman primates and in humans. [

Neurophysiology of Sexual Behavior

The eighteenth century Venetian Giacomo Casanova stated, “Only man is capable of real pleasure, because he is gifted with the power of thought, and he expects the desire, he studied it, he gives and remembers her, if he has enjoyed it (https://www.aphorismen.de/zitat/67814). Casanova suggests that three main aspects of human sexuality are pleasure, desire, and thought, and implies that human beings are perhaps unique in the animal kingdom in that for humans, sex in mainly in the brain. In reality, the neurophysiological regulation of sexuality shares many similarities in humans and other primates. Pleasure and desire are mainly located in subcortical midbrain structures, which are homologous among primates. Therefore, it is likely that the way human beings desire sex and experience sexual pleasure is very similar to the other primates do it. With regard to thinking about sex, especially conscious thinking, the situation is more complicated, as humans are unique among the primates for having a large neocortex that allows for conscious thinking. The phylogenetic increase in the size of the neocortex from monkeys to apes to humans seems to be related both to the rate of neuronal projections from the midbrain to the neocortex as well as to how the neocortex has evolved (Raghanti et al. ).
The vertebrate brain has several areas that regulate the emotional aspects of sex as well as the performance of sexual acts. The comprehensive comparative analysis by O'Connell and Hofmann () pointed out that brain regions representing the social behavior network and the mesolimbic reward system are particularly important for the sensation of pleasure. The size of the hypothalamic nuclei in the social behavior network is sexually dimorphic. The larger male nucleus of the preoptic area (POA) and the bed nucleus of stria terminalis (BNST) are exposed to testosterone during ontogenetically sensitive periods (Hofman and Swaab ). Such exposure produces concentration-dependent androgen receptor fields, which are essential for promoting male reproductive behaviors during adulthood. An important functional role of the POA is to integrate external and internal information to facilitate mating behavior and gender identity (Garcia-Falgueras et al. ). Research on female macaques has revealed neuronal activity in the ventromedial hypothalamus (VMH) and POA areas during sexual activity (see Dixson ). The sex drive in humans and in nonhuman primates is regulated by both androgens and estrogens (Fisher et al. ; but see Cappelletti and Wallen ).
A dopaminergic influence in the POA on sexual arousal has also been documented (Schober and Pfaff ). The mesolimbic reward system is one of the best investigated brain areas in medicine and biology. Comparative studies on fishes, amphibians, reptiles and mammals have revealed analogous functional neuroanatomic structures (O'Connell and Hofmann ). The monoamine neurotransmitter dopamine and its two-class receptor system (Missale et al. ; Beaulieu and Gainetdinov ) are key players in these mesolimbic structures. They mediate pleasure associated with predictive, motivational or attentional sensations in relation to learning processes (Berridge and Kringelbach ). The dopaminergic system is linked to the prefrontal cortex to mediate cognitive processes generated subcortically in association with sex-related emotion and behavior. In the prefrontal cortex, the enzyme catechol-o-methyltransferase is responsible for deactivating dopamine (Cumming et al. ), while the dopamine transporter protein regulates the duration of dopamine receptor activation (Giros and Caron ). Comparative analyses of cortical dopaminergic innervation in humans and nonhuman primates reveal no quantitative differences between chimpanzees, macaques, and humans. However, the sublaminar patterns of innervation differ in specific areas between humans and the other two species (Raghanti et al. ).
The main brain structures of the mesolimbic reward system are the striatum (STR: compulsive behavior), ventral tegmental area (VTA: motivation, reproduction, parental care), medial amygdala (meAMY: aggression reproduction, parental care, social recognition), ventral pallidum (VP: emotional learning, parental behavior), nucleus accumbens (NAcc: emotional learning, impulsivity, motivation, parental care), and the hippocampus (HIP: spatial learning) (see O'Connell and Hofmann ; Berridge and Kringelbach ). In humans the subcortical and cortical cognitive aspects of sexual pleasure are related to neural activity in the medial orbitofrontal, mid insular, and the anterior cingulate areas (de Araujo et al. ). Most of the research on the orbitofrontal cortex has focused on sensory integration and reward value in relation to food (Kringelbach ). According to Rilling () the reciprocal behavior of food-sharing among non-related hunter-gatherer populations provides a window into important neurobiological aspects of human social evolution. fMRI studies confirmed that the orbitofrontal cortex is also activated during reciprocal prosocial interactions (Waytz et al. ). We argue that in addition to food-sharing and other prosocial behaviors, sexual reward also played an important role in the evolution of the primate orbitofrontal cortex in relation to subcortical brain areas (see Rudebeck and Murray , and Wikenheiser and Schoenbaum ). Interestingly, both brain areas - the social behavior network and the reward system - consist of highly interactive nodes and overlapping structures, which represent an integrated evolutionary ancient social decision-making network (O'Connell and Hofmann ).

Sex Steroid Hormones and their Receptors

Sex steroid hormones, in particular brain estrogen concentrations, significantly modulate changes in women’s mood, cognition or sexuality across the menstrual cycle. The actions of estrogen in the brain depend on estrogen receptors, which occur in two isoforms: ERα and ERβ. The latter mediate subcortical cognition processes between hormonal components and expressed behavior. Patchev et al. () demonstrated that activating ERα receptors in neonatal female rats resulted in impaired ovarian function and reduced sexual behavior in adulthood. This treatment affected the morphology of the subcortical brain areas such as the periventricular nucleus of the hypothalamus (AVPV; it produces GnRH in humans and nonhuman primates) and POA, namely, it made these areas more masculine. In contrast, activation of ERβ receptors failed to alter later female sexual behavior or responsiveness to estrogens and did not affect the morphology of the POA. In situ hybridization in ovariectomized and hysterectomized female macaques showed the distribution density of ERβ mRNAs for subcortical hypothalamic, limbic and midbrain areas. Administering estrogens did not alter overall receptor densities but, progesterone treatment down-regulated the receptor signal in specific hypothalamic and hippocampal regions (Gundlah et al. ). Generally, estradiol influences ERα receptors in subcortical areas such as POA and VMH (both areas belong to social behavior network, which coordinates sexual activity and is multi-connected with the reward system) in ewes (Fergani et al. ). Higher estradiol and lower progesterone concentrations are related to elevated receptor activity and affect sexual behavior under the influence of an LH surge in both areas (Fergani et al. ). This scenario seems to be typical for mammalian mid-cycle stages. Similar results were documented for a macaque species, in which estrogen receptor activity was investigated in several brain areas in mated and unmated females. Mated females had significantly increased receptor activities in POA and VMH regions compared to unmated ones (Michael et al. ). Another primate study focused on the ERα and progesterone receptor density in hypothalamic regions of ovariectomized aged and young rhesus macaque females after long-term estradiol treatment. The hormonal treatment mimicked therapeutic supplements in peri-menopausal women. Surprisingly, old macaque females maintained estrogen receptor expression, and long-term estradiol supplementation only marginally influenced the receptor density (Naugle et al. ). In humans, there is evidence that brain masculinization is AR (androgen-receptor)-mediated rather than ER-mediated but the issue remains controversial (Luoto and Rantala ; Motta-Mena and Puts ; Puts and Motta-Mena ).
The impact of estrogen on the central dopaminergic system and on the brain reward system is also significant. Menopausal women more often exhibit symptoms of Parkinson and schizophrenia diseases, which are related to decreased dopamine production or transmission rates compared to individuals with cycling estrogen fluctuations (Cyr et al. ). Moreover, decreased dopamine release also seems to be related to the development of drug addiction. Accordingly, Lynch et al. () indicated that in adults drug abuse is more likely in males than in females; in adolescent individuals, however, drug addiction is only marginally different between the sexes. Studies of self-administration of alcohol in rats and vervet monkeys showed that females consume higher amounts of alcohol than males. In rhesus macaques, however, the sex difference was reversed (Lynch et al. ). Short-term self-administration of heroin did not differ in in male and females rats. In contrast, extended access to this drug was associated with higher self-administration in females (Lynch et al. ). Cycling women show a dependence of euphoria on d-amphetamine with regard to behaviors such as liking, wanting, or energy, and intellectual improvements during later follicle periods (Justice and de Wit ). Moreover, estradiol seems to improve subjective feelings of pleasure and feeling “high” in association with amphetamine (Sofuoglu et al. ). Nicotine withdrawal, instead, correlated with premenstrual symptoms during the late luteal phase of the cycle (Allen et al. ). These and other studies have shown that estradiol decreases the dopamine reuptake and therefore increases dopamine concentration in the synaptic cleft. This accelerates the binding rate for dopamine at D1 and D2 receptors, while reducing it for D3 receptors in the mesolimbic reward system (see Almey et al. ). Ultrastructural analyses of estrogen receptors within dopamine terminal regions such as the medial prefrontal cortex identified such receptors in extranuclear sites of neurons and glia; the highest densities were recorded at axons and terminals (Almey et al. ).
The described neuro-circuitry of the reward system, which includes the interplay between the dopaminergic system and estrogen, also plays a significant role in female decision making. In one study of rats, females were tested using an effort-discounting task with different types of reward: pressing a lever once yielded two pellets, pressing it many more times yielded four pellets. The results showed that ovariectomized females expressed a preference for the high-reward lever, whereas females treated with estradiol selected the low-reward lever. Moreover, the application of ERα receptor agonists, independently of ERβ agonists, resulted in high reward/high cost preferences, but simultaneous application of agonists for both receptor types decreased the choice for such high benefit/high cost options (Uban et al. ).
In addition to the dopaminergic system, it is important to consider also estrogen effects on the serotonergic brain system in relation to female sexual behavior. Introducing ovarian hormones into the dorsal raphe nuclei region of macaque brains altered the mRNA expression rates of components involved in serotonin metabolism (Pecins-Thompson et al. ). The rhombencephalic raphe nuclei complex is the origin of the serotonergic system. From here serotonergic fibers project into almost all brain areas (Holloway et al. ). Lower brain serotonin concentrations are related, for example, to depression, anxiety, and impaired cognition (Wallner and Machatschke ). Application of estrogen with or without progesterone increased tryptophan hydroxylase-I mRNA, but decreased mRNAs of MOA-A and concentrations of the serotonin re-uptake transporter. The latter impairs the relocation of serotonin metabolites from the postsynaptic membrane into presynaptic regions. All of these manipulations affect central serotonergic function (Smith et al. ), and serotonergic pathways are known to influence fluctuations in female mood and behavior during the menstrual cycle.
From neurophysiological research we conclude that the actions of estrogen and its related receptor system in the brain influence female behavior in a socio-sexual context. The distribution rate and density of receptor fields in subcortical brain areas enable estrogens to exert a major influence on female sexuality, food intake, mood changes, feelings of pleasure, and cognitive function in different phase of the cycles, in which estrogen concentrations vary significantly.

Conclusion

Women share with nonhuman primates subcortical brain areas, which are essential to modulate behavioral and physiological changes in relation to different reproductive cycle stages. These homologous regions represent evolutionarily conserved structures documented in nearly all vertebrates. The interconnected social behavior network and the mesolimbic reward system are responsible for a basic integration of sexual behavior and its related reward sensations. These sensations are not limited to sexuality, but also include food intake (Adam and Epel ) and prosocial interactions (Rilling ). Here, emotional rewards are produced mainly via the dopaminergic system. Research on rhesus macaques has revealed two types of dopamine neurons, one excited by reward-predicting stimuli and the other inhibited by punishment-predicting stimuli (in this case, an airpuff). Importantly, more neurons are excited by both stimuli combined (Matsumoto and Hikosaka ). These results indicate that the dopamine system can differentiate between positive and negative signals. Matsumoto and Hikosaka () proposed the existence of two functionally distinct dopamine neurons, the airpuff-inhibited and the airpuff-excited type. They would be located in subcortical brain areas belonging to the mesolimbic reward system. In mammals, the mesolimbic reward system and other dopaminergic systems project to the prefrontal cortex, but the innervation density of the cortical striatum differs between humans and nonhuman primates (Raghanti et al. ). Moreover, the distribution of estradiol receptors in subcortical (Gonzales et al., 2007) and cortical areas suggests that value-oriented signals can be transformed into distinctive behaviors modulated by estradiol concentrations during different cycle phases. Such hormonal modulations are apparently homologous and stable in physiological and behavioral expression rates across species (Uban et al. ). Regardless of differences in the ways in which some primate species advertise or conceal ovulation, there may still be functional similarities in the way sexual stimuli are perceived, processed, and communicated. One important difference between humans and other primates may concern women’s strategic behavioral decisions in relation to their fertility. Women have to make sure that the prospective fathers of their children are able and willing to invest significant resources in themselves and their children to an extent that is rarely observed in nonhuman primates.
Pair-bonding mechanisms have evolved in humans to make possible cooperative investment in children between reproducing partners. Such social bonds, however, should not be confused with sexual monogamy. The earliest primate ancestors may have had a solitary lifestyle similar to that of nocturnal mammals. Their descendants adopted a multi-male, multi-female social system approximately 52 million years ago, and subsequently evolved pair-living and one-male groups (harems) approximately 16 million years ago. Across all primates, monogamy is a less frequent social system than harems or multi-male, multi-female societies (Shulez et al. ). Nonetheless, social bonding between the sexes is probably tighter in one-male units than in multi-male, multi-female groups. At the level of mechanisms, these bonds are mediated by the neuropeptides oxytocin and vasopressin, which are produced in the magnocellular neurons of the paraventricular and supraoptic nuclei of the hypothalamus. These neurons project into areas of the mesolimbic reward system, such as amygdala or hippocampus, and into regions of the social behavior network, such as the BNST or the POA (Meyer-Lindenberg et al. ). The projections into these subcortical brain areas suggest that social bonding mechanisms may be related to sexual activities, and in particular to their emotional positive rewards (Young and Wang ). Both brain areas are evolutionarily relatively old. Therefore, we suggest that the neural circuits regulating sex – its emotional positive reward in relation to pair-bonding - were established after the evolution of single-male units in humans and nonhuman primates. This means that the origin of advertising female sexually attractive signals is older and originated in multi-male, multi-female primate societies.
Women’s pre-fertilization selection process for socially compatible and genetically valuable partners with high status and resources is time-consuming and subject to female-female mating competition. Women’s fat reserves, which are needed for succesful ovulation, gestation, and lactation, can contribute to permanent signals of sexual attractivenss such as large breasts and buttocks, which may signal physical and genetic fitness. Such permanent sexual signaling may allow females lengthier periods of mate assessment and more opportunities for mate choice without losing the interest of prospective partners. Studies have shown that men find attractive particular values of the waist-to-hip ratio as well as of the body mass index, which signals general health (Singh ; see also Havlíček et al. and commentaries). Additionally, breast morphology and size in fertile females may enhance the sexual attractiveness of the so-called hourglass body shape in women (see Dixson ). A question may arise as to whether men can perceive changes in female SSC in relation to culture-specific norms such as using different clothing during different cycle phases. For example (see also 2.4), the water content and parenchymal tissue volume increase in women during the luteal period and decreases during menstruation. As wearing clothes is common in most human societies, men are probably unable to recognize subtle cyclic changes in women’s bodies when these are covered by clothes. It is also unclear whether men can detect changes the bodies of women with whom they are in permanent, stable relationships. Male perception and interpretation of the information content of female SSC may result from direct comparison of their shape and size between women, independent of their cycle stage. Such individual differences may provide information about a woman’s health or reproductive fitness. In this context the American College of Radiology classified different mammographic density stages based on the fat-to-parenchymal tissue content in relation to the risk of developing cancer. Overall, a higher proportion of parenchymal tissue compared to fat is related to cancer (type 1, ≤ 25% of parenchymal tissue; type 2, ≤ 50%; type 3, ≤ 75%; type 4, ≥ 75% parenchymal tissue). This classification shows that the ratio can vary extremely. Therefore, the fat content of female SSC communicates information about health and energy resources available for reproduction and parental investment. But the attractiveness in particular breast sizes and/or shapes is not necessarily a fitness marker insofar as a significantly reduced fat proportion is related to less available energy resources and to increased health risks (see above). In this context, more subtle changes in other body parts during the cycle - the lipid content of the skin, the fat content of the thighs and abdomen, pigmentations, etc. – would provide significant information but they are presumably not reliably detectable by men, even those living in long-term partnerships.
Importantly, women do change their behavior in relation to cycle phases. Some of these changes are obviously linked to their culture. During periovulatory periods, women advertise their fertility not only by changing their gait, but also by wearing particular clothes and make-up; their consumer behavior and food consumption are also different. Advertising fertility through make-up or clothes would be analogous to cyclic changes in sexual swellings or face coloration in nonhuman primate females. Functionally, both the morphological changes in nonhuman primates and the behavioral strategies in humans are caused by female intra-sexual competition for valuable mates and by male mate choice. Interestingly, neither the morphological changes described in nonhuman primates nor the culture-specific behaviors of women seem to reliably signal fertility, ovulation, or readiness to mate: exaggerated swellings are also expressed during non-fertile cycle phases and sexy clothes can be worn by women in all phases of the cycle. Possibly, the culturally developed use of specific clothes to enhance and accentuate sexually attractive body areas in women can be interpreted as an example of culture – biology co-adaptation that better highlights permanently attractive SSC under competitive partner market conditions (Puts ).
If the female SSC of nonhuman primates and humans do not directly inform males about females’ fertility, − they might, in some cases, signal females’ genetic fitness and physical condition. For example, wearing particular clothes may allow women to make some of their attractive bodily characteristics, such as a thin waist and wide hips, more visible to men. Since women’s preferences for clothes and men’s preferences for body shapes are known to be different in relation to cultures and historical periods, a full understanding of female sexual signaling and male responses to it in humans requires the integration of biological and cultural analyses.
Posted by BipartisanAlliance2 at 5:46 AM 0 comments

When Black & Hispanic men are described as gay, they become stereotypically “Whitened” in addition to seeming less stereotypic of their own groups; they seem more affluent when described as gay

Racial stereotyping of gay men: Can a minority sexual orientation erase race? Christopher D. Petsko, Galen V. Bodenhausen. Journal of Experimental Social Psychology, Volume 83, July 2019, Pages 37-54, https://doi.org/10.1016/j.jesp.2019.03.002

Abstract: Decades of research indicate that the traits we ascribe to people often depend on their race. Yet, the bulk of this research has not considered how racial stereotypes might also depend on other aspects of targets' identities. To address this, researchers have begun to ask intersectional questions about racial stereotypes, such as whether they are applied in similar ways to men and women, or to children and adults. In the present studies, we examine whether men who are described as gay (vs. not) become de-racialized in the minds of perceivers. That is, we test whether gay (vs. non-gay) men are perceived as less stereotypic of their own racial or ethnic groups. Results consistently support the de-racialization hypothesis, regardless of whether targets are Black, White, Asian, or Hispanic. Moreover, when Black and Hispanic men are described as gay (vs. not), they become stereotypically “Whitened” in addition to seeming less stereotypic of their own racial groups. This “Whitening” effect is explained by Black and Hispanic men's seeming more affluent when described as gay (vs. when not), an effect that holds even when controlling for changes in these men's stereotypic femininity. Collectively, these findings underscore the point that race and sexual orientation are not orthogonal in the minds of perceivers. A minority sexual orientation can alter the racial characteristics ascribed to men, reducing the perceived presence of race-typical traits and, for low-SES men, increasing their perceived “Whiteness.”
Posted by BipartisanAlliance2 at 2:46 AM 0 comments

Leaders of gov't-favored firms are more likely to agree with sometimes contradictory ideas like markets should be generally free, but at present, the US market is too free, & competition is unfair

Matthew D. Mitchell, with Scott Eastman and Tamara Winter. “A Culture of Favoritism: Corporate Privilege and Beliefs about Markets and Government.” Mercatus Special Study, Mercatus Center at George Mason University, Arlington, VA, March 27 2019. https://www.mercatus.org/publications/corporate-welfare/culture-favoritism

Abstract: This paper discusses a national survey of business leaders that sought to determine how government favoritism toward particular firms correlates with attitudes about government, the market, and selectively favorable economic policy. Findings indicate that those individuals who believe they work for favored firms are more likely to approve of free markets in the abstract but also more likely to say the US market is currently too free. These individuals are more skeptical of competition and more inclined to approve of government intervention in markets. They also are more likely to approve of government favoritism and to believe that favoritism is compatible with a free market. Those who have direct experience with economic favoritism or are more attuned to such favoritism are more likely to have distorted perceptions of free- market capitalism and are more comfortable with further favoritism.

Keywords: favoritism, culture, corporate welfare, privilege, rent-seeking, cronyism, crony capitalism


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From the summary: Compared with other business leaders, the leaders of favored firms are more likely to agree with the following— sometimes contradictory—statements:

How Favored Firms Think about Markets
*  Markets should be generally free (at least in the abstract), and a freer market serves the general public.
*  But at present, the US market is too free, and competition is unfair to business.

How Favored Firms Think about Government
*  Government should more heavily regulate markets.
*  Regulations benefit consumers.
*  Regulations benefit the economy.
*  Competition is limited by government (they may view this as a good thing, given their belief that competition is unfair to business).

How Favored Firms Think about Favoritism
*  Government should favor specific businesses and industries.
*  Markets should be free, and government should favor particular firms (a contradictory set of beliefs).
*  Government assistance has a positive effect on the economy.
*  Customer focus and a unique business model are not the most important factors in business success.
*  The most important factors in business success are either knowledge of influential policymakers or government assistance.

Consequences of Favoritism

In some quarters of the business world a culture exists that legitimizes government favoritism. It encourages business leaders to seek government privileges and policymakers to offer them. Not only is this culture of favoritism expensive to taxpayers and consumers, it may also undermine the public’s faith in markets and economic freedom. If such attitudes persist or expand, then free, open, and competitive markets may be in peril. We risk stunted economic growth, wasted resources, and higher levels of corruption as a result.
Posted by BipartisanAlliance2 at 2:12 AM 0 comments

Users are likely to argue over wide ideological divides, and are increasingly likely to engage with those who are different from themselves

Why Keep Arguing? Predicting Engagement in Political Conversations Online. Sarah Shugars, Nicholas Beauchamp. SAGE Open, March 27, 2019. https://doi.org/10.1177/2158244019828850

Abstract: Individuals acquire increasingly more of their political information from social media, and ever more of that online time is spent in interpersonal, peer-to-peer communication and conversation. Yet, many of these conversations can be either acrimoniously unpleasant or pleasantly uninformative. Why do we seek out and engage in these interactions? Who do people choose to argue with, and what brings them back to repeated exchanges? In short, why do people bother arguing online? We develop a model of argument engagement using a new dataset of Twitter conversations about President Trump. The model incorporates numerous user, tweet, and thread-level features to predict user participation in conversations with over 98% accuracy. We find that users are likely to argue over wide ideological divides, and are increasingly likely to engage with those who are different from themselves. In addition, we find that the emotional content of a tweet has important implications for user engagement, with negative and unpleasant tweets more likely to spark sustained participation. Although often negative, these extended discussions can bridge political differences and reduce information bubbles. This suggests a public appetite for engaging in prolonged political discussions that are more than just partisan potshots or trolling, and our results suggest a variety of strategies for extending and enriching these interactions.

Keywords: politics, social media, interpersonal communication, deliberation, polarization, natural language processing, topic models, sentiment

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Introduction

Digital communication plays a critical role in our political infrastructure. Online platforms have expanded the reach of “kitchen table conversations,” as people increasingly turn to social media as a primary news source (Bakshy, Messing, & Adamic, 2015; Lee & Ma, 2012; O’Connor, Balasubramanyan, Routledge, & Smith, 2010) and elected officials use digital channels to communicate with their constituents (Farina, Epstein, Heidt, & Newhart, 2013; Kavanaugh et al., 2012). Such interactions are often modeled as one-shot games or as evidence of long-term links in a social network (Feng & Wang, 2013; Myers & Leskovec, 2014). Yet, much online activity consists not of single-shot, unidirectional interactions with elites, but repeated interactions among peers. These iterated interactions—conversations—have important implications for political theory: while conventional wisdom claims that brief social media interactions have little effect on subsequent online behavior, a number of recent experiments have shown modest but real effects of single-shot interactions (Friggeri, Adamic, Eckles, & Cheng, 2014; Munger, 2017). Deliberative theory suggests that repeated interpersonal interactions where individuals engage in extended conversation may have even more substantial effects (Axelrod, 1987; Bednar & Page, 2007; Habermas, 1984).
In this article, we focus not on persuasive outcomes but on the more fundamental question of what leads people to engage in extended online conversation and argument in the first place. Existing work in this area has generally had a more practical bent, focusing on tweet- or conversation-level recommendation and aiming to predict user interest in conversation threads to better curate and recommend targeted content. Such work has looked at user engagement in various forms of online conversation (Chen et al., 2012; He & Tan, 2015; Vosecky, Leung, & Ng, 2014; Yan, Lapata, & Li, 2012), as well as via retweeting (Feng & Wang, 2013; Hong, Doumith, & Davison, 2013) and re-entry back into existing conversations (Backstrom, Kleinberg, Lee, & Danescu-Niculescu-Mizil, 2013). Our work here is closest to the latter: We are more interested in the extended dynamics of conversation, particularly the decision to re-engage or exit, than in the initial decision to interact. We focus on users who have already made that initial participation, and seek to understand and predict whether and when they re-engage based on user, tweet, and thread-level features.
While ongoing deliberative conversation is the substantive focus here, this framing also turns an impossible problem—predicting initial responses to a tweet out of the entire pool of twitter users—into a practicable prediction task—predicting re-participation of users whom we know are already part of a conversation. This approach also conditions out the even harder problem of explaining the origins of an initial tweet or conversation, particularly given the immense variety of motivations behind those first moves. Instead, we focus on existing conversations—at least a first move followed by a response—and model the processes that lead to extended and branching conversations among existing participants. Twitter might seem less suited to such models than traditional online forums, but Twitter in fact produces immense quantities of impromptu extended, branching conversations, and by focusing only on re-entry by existing participants, we can study what causes individuals to continue an argument or drop out, bracketing the question of initial engagement.
By conditioning on existing user interaction, we aim to get more deeply at the question of why people bother arguing online. What brings them back to a repeated argument? What factors contribute to an individual returning to or abandoning an argument? While in face-to-face settings, social etiquette suggests that a comment will most likely be greeted with a response, there is no a priori reason to expect a response to the vast majority of online posts. While we expect to find many types of conversations occurring online, we might expect that more extreme content (positive or negative) will increase engagement, as trolls successfully incite arguments and partisan allies reinforce each other’s positions (Cheng, Danescu-Niculescu-Mizil, Leskovec, & Bernstein, 2017). Between the extremes lies a more productive and interesting mode of engagement: true deliberative argument, in which participants exchange content in a genuine attempt to persuade or inform. Such behavior is not as uncommon as skeptics might assume, and is prevalent in knowledge-sharing platforms such as StackOverflow, Yahoo! Answers, and other such forums, where users may be motivated to some degree out of a general sense of community (Adamic, Zhang, Bakshy, & Ackerman, 2008; Anderson, Huttenlocher, Kleinberg, & Leskovec, 2012; Oktay, Taylor, & Jensen, 2010) even as they argue over better or worse solutions to shared problems.
We find evidence for all of these behaviors in our data and, in particular, show that while many of these engagements are negative, conversations often cover a range of emotions and go on far longer than a single-shot attack or mutual trolling might suggest. While we leave for later the ultimate question of persuasive effect, we establish here that even a medium as apparently unpromising as Twitter is full of complex, extended political conversations, and that individuals’ decision to repeatedly re-engage in those conversations is surprisingly systematic.

Related Work

Much of the theoretical work around questions of conversational dynamics has been done within the literatures of deliberation and persuasion. While both these approaches focus their attention on back-and-forth conversations, they vary in their characterization of those conversations. The persuasion literature looks broadly at how people convince others and “win” arguments, while the deliberative ideal imagines thoughtful participants reasoning together to generate public opinion centered on the common good (Cohen, 1989; Habermas, 1984). “Reasons” may constitute factual arguments or emotional appeals (Mansbridge, 2015), but ideal deliberation is often taken to be free of persuasion, coercion, or other forms of instrumental action (Habermas, 1984). Contra persuasion models, ideal deliberators should engage in rational speech acts—aiming to honestly express themselves and truly trying to understand the other. Huckfeldt, Mendez, and Osborn (2004) argue that ideal citizens “are those individuals who are able to occupy the roles of tolerant gladiators—combatants with the capacity to recognize and respect the rights and responsibilities of their political adversaries” (p. 91) If political debate serves to sharpen our own understanding and build our collective knowledge, then we owe it to our interlocutors to press them on their positions, to find the holes in their armor and encourage refinement of beliefs. The process of debate makes us all better—thus allowing tolerant gladiators to walk away as friends. Citizens who silence their discussants, seek to coerce others, are easily persuaded by false beliefs, or who otherwise refuse to engage in rational argument, therefore, do a disservice to themselves and to their communities.
Experience tells us, however, that such a lofty deliberative ideal is rarely met in political conversation. Sunstein (2002) advances the “law of group polarization,” finding through numerous empirical studies that “deliberation tends to move groups, and the individuals who compose them, toward a more extreme point in the direction indicated by their own pre-deliberation judgments” (p. 175). Sunstein argues this polarization is the natural result of the social context, which serves as a significant driver of individual actions and opinions. Hearing friends express a view makes a person socially inclined to express the same view. In other words, deliberating groups tend toward extremism in the direction of the predeliberation median because nobody wants to take the social risk of expressing an unpopular view. Sanders (1997) similarly argues that the broader context of power dynamics frequently has a debilitating but under-recognized effect on deliberation, as marginalized individuals feel silenced and unable to share their true opinions. Importantly, the majority of participants may mistakenly assume that such power effects are negligible if “deliberation appears to be proceeding.”
Another line of work has tackled conversational dynamics from the perspective of the data-processing problem of platform curation, for example, trying to predict which posts will be popular for the purpose of highlighting those posts for users. Much of this work focuses on post-level engagement, predicting engagement as a function of topics (Hong et al., 2013) or social network structures (He & Tan, 2015; Pan, Cong, Chen, & Yu, 2013). Much of this work has considered “popularity” as a raw aggregate of engagement with an initial post, finding, perhaps unsurprisingly, that the popularity of a user’s past content is a strong predictor for the popularity of their future content (Artzi, Pantel, & Gamon, 2012). Backstrom et al. (2013) break the task into related subtasks: length prediction and re-entry prediction. Intuitively, these subtasks indicate distinctive types of threads: threads which are long because a high number of users chime in a small number of times—to offer congratulations or condolence, for example—while other threads are long because a small number of users contribute a large number of times in a back-and-forth conversation. Supporting this theory, Backstrom et al. (2013) find that the number of distinct users in long threads follows a bimodal distribution. Using data from Facebook and Wikipedia, Backstrom et al. (2013) find the identities of recent commenters is most predictive of conversation re-entry.
This lattermost line of work is largely atheoretical and not particularly concerned with normative issues. While the current study borrows many of their methods, we are also fundamentally interested in the dynamics of online conversation from a deliberative perspective. Thus, we are interested less in conversation recommendation or modeling engagement in conversations per se, and more focused on how individual speech acts (tweets) lead existing discussants to re-engage with each other or abandon a conversation. Regardless of the outcome of a conversation, it is important to understand what sustains conversations—particularly acrimonious ones—and keeps mutual opponents or supporters engaged with each other. As we will see, this engagement can take more or less productive forms, but simply understanding the deliberative dynamics is an important first step.
Posted by BipartisanAlliance2 at 1:57 AM 0 comments

Wednesday, March 27, 2019

A genetic mutation 60k to 130k years ago increased the capacity of general working memory or phonological storage, final piece in the evolution of human executive reasoning ability, language, & culture

Manoochehri, Majid. 2019. “The Evolution of Memory Span: A Review of the Existing Evidence.” PsyArXiv. March 27. doi:10.31234/osf.io/zdsya

Abstract: Memory span in humans has been intensely studied for more than a century. In spite of the critical role of memory span in our cognitive system, which intensifies the importance of fundamental determinants of its evolution, few studies have investigated it by taking an evolutionary approach. Overall, we know hardly anything about the evolution of memory components. In the current study, I reviewed the experimental studies of memory span in humans and non-human animals and the evolutionary hypotheses.

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Memory span refers to the ability of an individual to reproduce immediately, after one presentation, a series of discrete stimuli (e.g., digits, letters, and words) in their original order (Blankenship, 1938). Hermann Ebbinghaus (1850-1909) has been known as one of the first researchers of memory span. He studied the number of trials that it took him to memorize sequences of nonsense syllables (Ebbinghaus, 1885). He found that the number of trials needed increased with the length of the sequences. He then commented that: “The question can be asked: What number of syllables can be correctly recited after only one reading? For me the number is usually seven” (p. 36). In the years after that, several studies of memory span with verity of methods, tasks, and materials have been done by others (for review see Blankenship, 1938; Dempster, 1981). Surprisingly, some parts of results, such as the average memory span of adults were almost always the same. In 1956, Miller in his article discussed this issue. He stipulated that: “Everybody knows that there is a finite span of immediate memory and that for a lot of different kinds of test materials this span is about seven items in length” (p. 11). Today Miller’s suggestion has been known as the “magical number seven” of Miller, which refers to the memory span of young English adults. However, further findings from other nations were also in accordance with these results, suggesting that a memory span of about seven items is a universal characteristic of human beings. In addition to this feature, memory span scores have been discussed to be invariable and resistant to Flynn effects (Gignac, 2015; Wechsler, 1939). Moreover, memory span scores do not show considerable sex differences (Lynn & Irwing, 2008).The question that arises here is which selection pressures or evolutionary events caused the current memory span of humans and its particular characteristics.

The memory span of non-human animals
Firstly, it should be considered that because of the particular difficulties of studying cognitive functions in non-human animals, designed tasks in most of the available studies are somehow easier than classical memory span tests in humans. They usually include recognition of items instead of imitating the sequences, or several hours practice before the main test.

Chimps and other primates
Few studies have investigated memory span in non-human animals. Chimpanzees have been known as one of our nearest primate relatives and also one of the smartest non-human animals. Therefore, it may be expected to find the largest memory span of non-humans in them. The existing evidence shows that chimpanzees have a memory span of about 5 items (Inoue & Matsuzawa, 2007; Kawai & Matsuzawa, 2000). The results of other primates are very close to that of chimpanzees. Studies in baboons reveal a memory span of about 4 to 5 items (Fagot & De Lillo, 2011). On the other hand, the results of studying two rhesus monkeys by Swartz et al. (1991) suggest a memory span of about 4 objects.

Non-primates
Studies of non-primates do not exhibit better performances. Herman et al. (2013) have suggested a memory span of about 4 to 5 items for bottlenose dolphins. Lately, Toyoshima et al. (2018) have stipulated that rats are able to remember 5 objects at once. By contrast, a previous similar work by Sugita et al. (2015) has argued that rats’ memory span is approximately 4 items. A memory span of 4 items has also been suggested for pigeons. Terrace (1993) has discussed that the amount of time it takes a pigeon to learn a 4-item list (i.e., 3-4 months) suggests that 4 items may approach the limit of the pigeon's memory span.
Taking all these data together, one may conclude that there is an increasing trend of memory spans with a gentle slope from other animals to us. Moreover, it also seems reasonable to argue that while the memory span of most of the mentioned animals is about 4 to 5 items, humans’ memory span is about 7 items, which implies a sudden increase. This can be interpreted in favor of Coolidge and Wynn's (2005) hypothesis. They proposed that a mutation increased the length of memory span in the relatively recent human past. No need to emphasize that the idea of an increase with a gentle slope or a sudden increase is based on only a few experiments of memory span in some non-human animals. Surely, more studies are needed to provide the exact pattern. Experimental studies are also essential to measure the memory span of the current hunter-gatherers societies, such as Hadza of Tanzania. There are several reasons for the importance of their memory span results. Namely, because they are still foragers and their lifestyle is very close to that of our hunter-gatherer ancestors. Accordingly, their memory span might be similar, too. In addition, they are not literate or numerate and do not live in information-based societies. Therefore, they are not affected as broadly as other societies by some elements such as advanced educational programs. Moreover, another question is whether they apply memory’s strategies similar to people from other societies or not.

Evolutionary discussions and hypotheses
Until today, few studies have discussed memory span from an evolutionary perspective. There are also scant studies that discussed the evolution of working memory (e.g., Carruthers, 2013). It should be noticed that there are considerable differences between the functions of memory span and working memory. Therefore, there might be different selection pressures on them. In the present study the primary focus is on memory span.
Given the question of why memory span of humans has such a limited capacity, MacGregor (1987) based on a mathematical discussion emphasized the importance of an efficient retrieval. He suggested that: “… in a memory system evolved for efficient retrieval, there is an upper effective limit to short-term memory” (p. 107). From his point of view, there is an upper effective limit for the number of items in memory span, and this limitation guarantees an efficient retrieval.
The evolution of memory span has been also discussed by Coolidge and Wynn (2005). Although they mainly focused on working memory, the phonological lop which refers to memory span (or verbal memory span), has also been argued in their study. The core suggestion of their article is that a genetic mutation affected neural networks approximately 60,000 to 130,000 years ago and increased the capacity of general working memory or phonological storage. In case of memory span, they stipulated that:” A relatively simple mutation that increased the length of phonological storage would ultimately affect general working-memory capacity and language” (p. 14). They emphasized that an enhancement of capacities occurred in the relatively recent human past, most likely after the first appearance of anatomically modern humans, and this development was the final piece in the evolution of human executive reasoning ability, language, and culture. From their point of view, the larger capacity is a necessary precondition for symbolic thought, which selective pressures contributed to the growth of it. They noted that an increase in memory span of pre-modern Homo sapiens would have allowed greater articulatory rehearsal, consequently allowing for automatic long-term storage, and the beginnings of introspection, self-reflection, and consciousness. They, provided some evidence to support the assumption of a genetic mutation, such as the beginnings of composite tool-making about 300,000 years ago, or an explosion of culture which began approximately 50,000 years ago.
    In another part of their article, Coolidge and Wynn (2005) have quoted from Alan Baddeley that: “the phonological store evolved principally for the demands and acquisition of language” (p. 9). In addition, they have proposed that, evolutionary, the visuospatial sketchpad which is a part of working memory and maintains visual and spatial information may be older than the phonological loop. It should be noticed that the visuospatial sketchpad refers to visual memory span.

Conclusions
In the first place, the present article draws attention to the gap of evolutionary studies of memory span. It also suggests an increasing trend of memory span from our ancestors to us, whether the trend includes a steady increase with a gentle slope or a sudden increase. In terms of evolutionary discussions, the few available studies which have argued the evolution of memory span concentrated on some particular issues such as the reasons of a limited-capacity construct, or the results of increasing the length on cognitive functions. Other aspects remain untouched.
Posted by BipartisanAlliance2 at 11:44 PM 0 comments

Latent genetic traits account for, on average, 40.63% of variance in traditional and online political talk, discussion with agreement and disagreement, and political conflict avoidance: Results from two twin studies

Genetic influence on political discussion: Results from two twin studies. Chance York. Communication Monographs, Mar 26 2019. https://doi.org/10.1080/03637751.2019.1597274

ABSTRACT: Two twin studies are used to explore genetic influence on political discussion. Results from both studies demonstrate latent genetic traits account for, on average, 40.63% of variance in traditional and online political talk, discussion with agreement and disagreement, and political conflict avoidance. Taken together, the findings suggest a heritable genetic mechanism may partly explain why individuals vary across multiple dimensions of political discussion and differentially experience discussion effects. Implications for the political discussion effects literature and for reconceptualizing the etiology of political discussion are discussed.

KEYWORDS: Political discussion, individual differences, behavior genetics, twin study, genes

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Political discussion is an important and beneficial form of communication in representa-tive democracies. Citizens who frequently discuss politics become more knowledgeableabout current events and public affairs, engaged civically and politically, and confidentin their own ability to affect their national government and its institutions (Eveland &Hively,2009; Kenski & Stroud,2006; Shah et al.,2017). Yet, citizens differ widely in behav-ioral dimensions of political discussion and thus any potential benefits they may derivefrom talking about politics. For instance, some citizens routinely discuss politics whileothers only talk about politics during salient election periods (Hardy & Scheufele,2009)if they engage in political discussion at all. Some citizens prefer face-to-face talk whileothers prefer online conversation and some citizens seek political argument whileothers seek agreement.
What accounts for these individual differences in political discussion? In the past, indi-vidual differences in political discussion have been thought to emerge from, and be con-strained by, personality characteristics (Gerber, Huber, Doherty, & Dowling,2012;Hibbing, Ritchie, & Anderson,2011), parent and peer socialization (Hively & Eveland,2009; Klofstad,2009, 2010, 2015), and a wide array of psychological motivations as out-lined in the Uses and Gratifications (U&G) theory of communication behavior(Eveland, Morey, & Hutchens,2011; Gil de Zúñiga, Valenzuela, & Weeks,2016;Kearney,2017). However, it is also plausible that far more fundamental traits–genes–precede and delimit these more immediate influences on discussion. Because genes arecentral to neuroanatomical development and neurochemical responses to external stimuli (Hatemi, Byrne, & McDermott,2012; Knopik, Neiderhiser, DeFries, & Plomin,2016; Lockyer & Hatemi,2018), they may indirectly promote pathways to explicit behav-ioral patterns, including patterns of interpersonal political communication. In addition,genes have been shown to regulate personality characteristics amenable to political talk,such as extraversion (Bouchard & Loehlin,2001). This is perhaps why genetic traitshave already been shown to partially explain orientations to interpersonal discussion gen-erally (Kirzinger, Weber, & Johnson,2012) and frequency of political discussion specifi-cally (Funk et al.,2010), though it remains unclear whether genetic traits also influenceother critical dimensions of political talk, including online political talk and discussionwith disagreement.
The purpose of this article is to therefore explore genetic influence on previously unex-amined aspects of political discussion. In this article, a behavior genetics perspective andtwin study survey data were used to ascertain the amount of variance in several dimen-sions of political discussion that can be attributed to latent genetic traits and the socialenvironment. Building on previous research (Funk et al.,2010; Kirzinger et al.,2012),the results show that variation in multiple dimensions of political discussion is partlyexplained by genetics. Importantly, the results suggest genes may be an overlookedfactor motivating behavioral differences in political discussion and its effects. Moreover,the results imply a need to reconceptualize the etiology of political discussion as beingshaped by both social-environmental and biological forces.

Literature review

Talking about politics is associated with a number of desirable effects. For example, pol-itical discussion is related to enhanced knowledge about political candidates and issues(Eveland,2004; Eveland & Hively,2009), more frequent engagement in civic and electoralprocesses (Bakker & De Vreese,2011; Klofstad,2009, 2010, 2015) heightened confidenceone can make a difference politically (Kenski & Stroud,2006), and increased tolerance forindividuals with differing political opinions (Mutz,2002a). Political talk also acts as a keymediator of news media influence, altering selection and processing of news content(Anspach,2017) and augmenting positive effects of news exposure on civic and politicalparticipation by enabling citizens to make sense of mediated information (Cho et al.,2009;Shah et al.,2007, 2017; Shah, Cho, Eveland, & Kwak,2005). Although“cross-cutting”dis-cussion with un-likeminded partisans has been linked to reduced levels of participationwithin politically diverse social networks (Mutz,2002b, 2006), a considerable body of evi-dence has shown political discussion to be cognitively and behaviorally advantageous.
Individuals vary, however, in how they discuss politics and how frequently, and thusany informational and participatory benefits they may reap from discussion. Forexample, while some citizens are consistent political discussants regardless of external cir-cumstances, others might be characterized as“seasonal discussants”who are“uniformedand unengaged and usually do not participate in political discussions”unless they are“triggered by highly salient campaign coverage” (Hardy & Scheufele,2009, pp. 95–97).Still other citizens may avoid political talk altogether despite exposure to externalevents, such as national elections, and despite possessing a general interest in politics.Some citizens may prefer interactions that take place online while others seek out face-to-face conversation. Some may enjoy political discussion with disagreement whileothers abandon conflict in pursuit offinding common ground on the issues.
As with other forms of communication, several factors can motivate individual differences in political discussion. To date, in fact, the literature provides at least three sourcesof variation. First, political talk may arise from and be bounded by deeply ingrained personality characteristics such as extraversion. Extraversion, which can be defined as an“energetic approach to the social and material world”(Gerber, Huber, Doherty, &Dowling,2011, p. 267), has been linked to more frequent political discussion with friends, family, and distant social ties (Hibbing et al.,2011) as well as more frequent dis-cussions that involve disagreement (Gerber et al.,2012). Personality traits such as agree-ableness, conscientiousness, openness to experience, and emotional stability have alsobeen associated with political discussion frequency and discussion with disagreement(Gerber et al.,2012; Hibbing et al.,2011). From this perspective,“psychological predis-positions captured by individual personality traits play an important role in shaping thekinds of conversations citizens engage in, the setting for those conversations, and theinfluence discussion may or may not have on the individual”(Hibbing et al.,2011,p. 602).
Second, individual differences in political discussion may result from socialization viapolitical interactions with parents and peers that take place during childhood, adolescence,and young adulthood. Youth who belong to“concept-oriented”families that encouragekids to share their ideas, for instance, tend to engage in more frequent, more informedand“elaborative”talk with their families (Hively & Eveland,2009) that may, in turn,shape how they discuss politics in the future. Similarly, discussing politics with collegeroommates has been linked to increased short-term civic and political participation (Klof-stad,2009) and long-term discussion habits (Klofstad,2010; 2015). An individual’s earlyexposure to political talk, especially discussions with parents and peers, may thus play amajor role in discussion patterns over the life course.A third source of variation in political discussion comes from the U&G theory of com-munication behavior. Specifically, U&G suggests that individuals are active communica-tors who engage in interpersonal discussion in a manner that is“goal-directed,purposive, and motivated”by deliberate choices to satisfy immediate psychologicalneeds to communicate affection, promote feelings of social inclusion, escape from one’sday-to-day routines, and relax with close social ties (Rubin,2009a, p. 167; see Barbato,Graham, & Perse,1997, 2003; Graham, Barbato, & Perse,1993; Rubin,2009b; Rubin,Perse, & Barbato,1988).
Politically oriented discussions may likewise satisfy needs to per-suade politically, express political opinions, enhance issue learning (Eveland et al.,2011;Gil de Zúñiga et al.,2016; Yoo, Kim, & Gil de Zúñiga,2017), as well as maintain one’spolitical identity and feel emotionally engaged via political interaction (Kearney,2017;Valenzuela & Bachmann,2015). Accordingly, the U&G theoretical framework suggeststhat individual differences in political discussion occur because people perceive discussionto satisfy differing informational and social needs.
As Sherry (2001) has noted, however, it is likely that individual differences in U&G needs and the communication behaviors they inspire originate in biological factors. Forinstance, while it has been suggested that U&G needs for communication are governed by psychological“ predispositions [and] the environment”(Rubin,2009a, p. 167), such“predispositions”like those rooted in personality traits are known to have an even more fundamental genetic basis (e.g., Bouchard & Loehlin,2001; Plomin, DeFries, Knopik,& Neiderhiser,2016). Additionally, it is established that because genes form the basis of human neuroanatomical development and control neurochemical responses to external stimuli, they ultimately provide pathways to explicit cognitive and behavioral patterns(Hatemi et al.,2012; Lockyer & Hatemi, 2018), including neural pathways that, alongwith social contexts, prompt and structure communication behavior (Beatty, McCroskey, & Pence,2009; Weber, Sherry, & Mathiak, 2009). It is therefore possible, as decades of twin research in the behavior genetics paradigm has shown, “that many physical, psychological,and behavioral traits, however indirectly, are the ultimate result of a combination ofgenetic inheritance and the environment” (Medland & Hatemi,2009, p. 192).

A behavior genetics approach to communication behavior
Behavior genetics researchers rely on known degrees of biological relatedness among survey respondents–typically, identical and fraternal twins–to estimate the impactof genes on observable outcomes. These outcomes have included highly specializedpsychological orientations and behaviors, such as political ideology, political party affilia-tion, and voter turnout (Hatemi et al.,2014; Hatemi & McDermott,2012; Hatemi,Medland, Morley, Heath, & Martin,2007); social and economic attitudes (Hatemi,Smith, Alford, Martin, & Hibbing,2015); educational attainment (Cesarini & Visscher,2017); conservativism, authoritarianism, and religiousness (Ludeke, Johnson, & Bouchard,2013); fear of social and political out-groups (Hatemi, McDermott, Eaves,Kendler, & Neale,2013), risk-taking behavior (Kreek, Nielsen, Butelman, & LaForge, 2005); and social cooperation and trust (Cesarini et al.,2008). Twin studies have also shown that genes play a powerful role in shaping dimensions of mental health (Strachan,Duncan, Horn, & Turkheimer,2017), personality (Bouchard & Loehlin, 2001; Plominet al.,2016), and a variety of physical attributes such as height, weight, heart function,and facial structure (Polderman et al.,2015).1
In communication research, twin studies have demonstrated that genes partially explain differences in broad traits and orientations such as communicator style (Horvath,1995) and communicative adaptability (Beatty, Marshall, & Rudd,2001).
Twin studies have also been used to explore genetic influences on media consumptionand interpersonal communication behaviors. For example, one twin study demonstratedthat individual variation in mobile phone use, frequency of talking on mobile phones, andfrequency of texting were all indirectly influenced by genetic traits (Miller, Zhu, Wright,Hansell, & Martin,2012). Similar studies have shown that latent genetic traits influence frequency of using social media sites like Facebook to communicate with friends and family (York,2017), problematic internet use or PIU (Deryakulu & Ursavaş, 2014), and television viewing (Plomin, Corley, DeFries, & Fulker,1990).2
Across twin studies of communication, genetic traits have been shown to account forlarge proportions of individual variance in outcomes. For example, Kirzinger et al.(2012) showed genetic traits explained between 9% and 29% of the variance in orientationsto interpersonal discussion measured using two Likert-type items that tapped engagement in discussion and self-reported enjoyment in talking with“a lot of different people atparties”(p. 164). Funk et al. (2010, pp. 31–32) showed that up to a third of variance intwo Likert-type items measuring frequency of political discussion and conflict avoidance was explained by genes. These latter twin studies, combined with research that has foundthat genes provide brain–behavior pathways (Hatemi et al.,2012; Lockyer & Hatemi,2018) that activate patterns of communication (Beatty et al.,2009; Weber et al.,2009),suggest that additional dimensions of political talk may be partly explained by genetic traits. Thus, one could expect genetic traits to explain a nontrivial amount of variance in multiple dimensions of political talk, including traditional political discussion, online political discussion, political discussion with agreement and disagreement, and political conflict avoidance.In addition to examining whether genetic traits explain differences in dimensions of political discussion, it is also instructive in twin research to address the relative explana-tory contribution of genetic traits and the social environment shared by both twins (e.g.,being raised by the same parents) to the behaviors under investigation. Based on previousresearch, especially that of Kirzinger et al. (2012) and Funk et al. (2010), it may be the casethat both genetic and environmental factors shared by twins in a pair account for individ-ual differences in dimensions of political discussion, though it is uncertain which of thesefactors would make a more substantial contribution. Therefore, a research question is alsoposed:What is the relative explanatory contribution of genetic and environmental factors tovariance in multiple dimensions of political talk, including traditional political discussion,online political discussion, political discussion with agreement and disagreement, and pol-itical conflict avoidance?
Posted by BipartisanAlliance2 at 12:45 PM 0 comments

Political journalists overwhelmingly interact with other journalists, particularly political ones, & their offline tendencies to form homogenous networks have transferred online

Exploring Political Journalism Homophily on Twitter: A Comparative Analysis of US and UK Elections in 2016 and 2017. Kelly Fincham. Media and Communication, Vol 7, No 1 (2019). March 21 2019. http://dx.doi.org/10.17645/mac.v7i1.1765

Abstract: The tendency of political journalists to form insular groups or packs, chasing the same angles and quoting the same sources, is a well-documented issue in journalism studies and has long been criticized for its role in groupthink and homogenous news coverage. This groupthink attracted renewed criticism after the unexpected victory of Republican candidate Donald Trump in the 2016 US presidential election as the campaign coverage had indicated a likely win by the Democratic candidate Hillary Clinton. This pattern was repeated in the 2017 UK election when the Conservative party lost their majority after a campaign in which the news coverage had pointed to an overall Tory victory. Such groupthink is often attributed to homophily, the tendency of individuals to interact with those most like them, and while homophily in the legacy media system is well-studied, there is little research around homophily in the hybrid media system, even as social media platforms like Twitter facilitate the development—and analysis—of virtual political journalism packs. This study, which compares Twitter interactions among US and UK political reporters in the 2016 and 2017 national elections, shows that political journalists are overwhelmingly more likely to use Twitter to interact with other journalists, particularly political journalists, and that their offline tendencies to form homogenous networks have transferred online. There are some exceptions around factors such as gender, news organizations and types of news organization—and important distinctions between types of interactions—but overall the study provides evidence of sustained homophily as journalists continue to normalize Twitter.

Keywords: elections; groupthink; homophily; political journalism; Twitter, UK; US

Check also Journalistic Homophily on Social Media: Exploring journalists’ interactions with each other on Twitter. Folker Hanusch & Daniel Nölleke. Digital Journalism, https://www.bipartisanalliance.com/2018/02/journalists-continue-to-live-in-bubbles.html

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The worst about this is not their constant sanctimoniousness when talking to the peasants, when they are bigger offenders and keep their membership in their echo chambers and sub-echo chambers in greater proportion that the great unwashed... It is that in journalism schools they are already told to be aware of their biases, and the very human need to be part of a pack (or herd?) and they forget it immediately after taking the exams.


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2. Literature Review
FromthetelegraphtotypewriterstotelevisiontoTwitter, successive technological innovations have transformed the norms and practice of journalism (Lasorsa, Lewis, & Holton, 2012) and each new technology has arrived amid much fanfare about its potential impact on political communication, particularly around election campaigns (Stromer-Galley, 2014). Ultimately however, the expectations and concerns about these potential utopias and dystopias have never been fully realized as the power structures of journalism and politics have instead normalized each new “new media” into their own practice (Singer, 2005). The potential power of digital media in election campaigns was first seen in the US in the 2004 Presidential campaign when it rocketed the relatively unknown candidate Howard Dean into the political and media stratosphere (Stromer-Galley, 2014) but as Margolis and Resnick had already argued in 2000, any of the digital advantages accruing to early adopters like Dean were soon eclipsed as the political and journalism elite folded these new technologies into existing practices when they recognized,a nd there by normalized, the “new” new media (Margolis & Resnick, 2000). Much of the research into Twitter journalism practice argues that journalists, seen as frequent, if not always skillful, Twitter users (Engesser & Humprecht, 2015) are well down the path of normalization, using Twitter in ways that conform to existing practice rather than using it to change journalism practice (see Lasorsa et al., 2012; Lawrence, Molyneux, Coddington, & Holton,2014; Lewis,2012; Molyneux & Mourão,2019; Nuernbergk,2016;Parmelee,2013). This is especially evidentinare as such as gatekeeping,wherejournalistshave long controlled whose voices make it through the editorial “gates” (Lasorsa et al., 2012; Singer, 2005), and Twitter gatekeeping can be seen in the “insider talk” and “regurgitation” of information flowing across Twitter (Lawrence et al., 2014; Parmelee, Roman, Beasley, & Perkins, 2019, p. 161) as journalists more frequently engage with other journalists or newsmakers—and even themselves—rather than interest groups, academics or citizens (Carlson, 2017; Molyneux & Mourão, 2019). While journalists can, and do, challenge normalization in other areas of journalism practice (see Broersma & Graham 2016; Molyneux & Mourão, 2019), this study’s sole concern is whether political journalists create homogenous packs on Twitter, thus supporting the idea of homophily, and by extension, normalization, even as the hybrid media system (Chadwick, 2013) theoretically presents alternatives to the pack model with a wider range of interaction partners and voices outside the bubbles. While some studies indicate more negotiation around normalization in newer affordances such as quote tweetsor areas such as monitoring, sourcing, publishing, promoting and branding (Broersma & Graham, 2016; Molyneux & Mourão, 2019; Tandoc & Vos, 2016), the research overwhelmingly indicates that journalists’ interactions are dominated by other journalists andthat these homogenous onlinenetworks resemblethosebuilt by journalists offline (Hanusch & Nölleke, 2018). However, despite the plethora of studies indicating that journalists’ Twitter networks are so homogenous as to suggest homophily there has been little research so far specifically into homophily in those interactions even as journalists themselves report low levels of citizen engagement. For example, Gulyas (2017) found journalist/ citizen interaction at 23 and 27 percent in the US and UK respectively, and Nuernbergk (2016) saw only rare interactions between German journalists and their Twitter followers, thus suggesting that political journalists still prefer to connect with each other in “journalism-centered bubbles” (Molyneux & Mourão, 2019; Mourão, 2015; Nuernbergk, 2016, p. 877). Additionally, researchers have noted evidence of bubbles within bubbles (Bentivegna & Marchetti, 2018) with political journalists seen as more likely to interact with other political journalists (Hanusch & Nölleke,2018); selfsegregating by gender (Artwick, 2013; Usheretal.,2018), and focusing on those inside their own news organization (Bentivegna & Marchetti, 2018; Larsson, Kalsnes, & Christensen, 2017) with Vergeer (2015) reporting that regional reporters were more likely to do this than national journalists. While these studies were broad in nature, Hanusch and Nölleke (2018) specifically considered thepotential impactofbeat, gender,organizational context and geographic proximity in an extensive inquiry into homophily among Australian reporters and found a high degree of homophily across those four sharedcharacteristics. Homophily, or the tendency of individuals to form groups with those most similar to themselves (McPhersonetal.,2001)wasintroduced as a concept in the 1950s when Lazarsfeld and Merton (1954) proposed that individuals were far more likely to build networks around shared values in areas like religion or sport or around shared status in areas such as race, ethnicity, sex, age, religion, education and occupation (Hanusch & Nölleke, 2018; McPherson et al., 2001). As an elite specialty within the wider occupational field of journalism, political journalists are perhaps more sensitive to the homophilous effects of these tight-knitgroups as they seek validation from “those to whom we compare ourselves, those whose opinions we attend to, and simply those whom weare aware of andwatchforsignals aboutwhat is happening in our environment” (McPherson et al., 2001, p. 428). The tendency for political reporters to focus on each other was first labelled as “pack journalism” during the 1972 US presidential election when Rolling Stone reporter Tim Crouse noted that the journalists’intentfocusoneacho therled to a shared groupthink about the day’s most important stories and created a pack dynamic so strong that “almost all the reporters will take the same approach to the story”, even though they were ostensibly competing against each other(Crouse,1973). As former Newsweek Bureau Chief Karl Fleming said: “Their (the reporters’) abiding interest is making sure that nobody else has got anything that they don’t have—not getting something that nobody else has”(Crouse,1973). While Crouse observed the political journalism network and the resulting groupthink from his physical seat on the campaign bus, researchers can now observe virtual political journalism networks from afar through the analysis of publicly-visible Twitter conversations and the use of affordances such as retweets, replies, mentions and followings. Retweet and mention networks (which include both replies and indirect mentions) are often seen as the strongest interaction markers (Hanusch & Nölleke, 2018) and several studies have reported differences in the way journalistsuseretweets and mentions with more homophily seen in mentions than retweets (Hanusch & Nölleke 2018; Molyneux & Mourão, 2019; Nuernbergk, 2016). However, indirect mentions can be also be used as a “shout out” (Usher et al., 2018) thus diluting their effectiveness as a distinct measure of interactive intent. Retweets, despite multiple Twitter disclaimers to the contrary (Hanusch & Nölleke, 2018), are most often viewed as an endorsement of content (Meraz & Papacharissi, 2013; Russell, Hendricks, Choi, & Stephens, 2015), but they also convey endorsement of the user and the link between the original and retweeting sender provides evidence of a pre-existing homophilous network of like-minded people (Bruns & Burgess, 2012; Hanusch & Nölleke, 2018). While some journalists use replies to thread longer posts together and circumvent Twitter’s 280-character count (Molyneux & Mourão, 2019, p. 257), specific replies (as against indirect mentions) are more typically interactive with some research indicating potential heterophily with studies showing “public/citizen” users receiving as high as 48 percent of the journalists’replies (Brems, Temmerman, Graham, & Broersma, 2017). However, these studies don’t mention if the accounts received more than one reply which would help us consider the nature and value of such interactions, a problem noted by Parmelee and Deeley in 2017, when they queried the use of simple counts arguing that such one-offs were inadequate ways to measure reciprocity. Such reciprocity is often absent in followings (Kiousis, 2002) and, as Ausserhoffer and Maireder reported in 2013, followings are not a reliable metricasthey can bepaid for or artificially enhanced by computer scripts. Subsequently, this study views the affordances of retweets and replies as more indicative of actual intent, highlighting the user’s value to the journalist (Conover et al.,2011; Molyneux, 2015). Frequency of interactions is also important. As McPherson et al .(2001) outlined, homophily can be seen in those whose “opinions we attend to” and given the concerns raised by Parmelee and Deeley (2017) around one-off replies, this study measures interactivity by focusing on the political journalists’ most-frequent discussion partners in replies and retweets to see which voices the journalists most frequently attend to. This research builds on the developing work into Twitter journalism homophily (see particularly Hanusch & Nölleke, 2018) and is important as it is the first to examine this issue in the context of social media election coverage, specifically on Twitter, and takes the analysis further by looking at media practice in two similar media systems. The importance of studies such as this, which examine these “new” types of interactions on social media, cannot be overstated as the work done by political journalists remains essential to a citizen’s ability to understand politics and election campaigns even in a digital and networked age (Harder, Paulussen, & VanAelst, 2016; Kuhn & Nielsen, 2014).


3.Research Questions
This study explores retweets and replies as two distinct affordances and explores them separately for the presence of homophily by asking the following two research questions:

RQ1: To what extent can homophily be identified in political journalists’ retweets on Twitterin an election campaign?
RQ2: To what extent can homophily be identified in political journalists’ replies on Twitter in an election campaign?

Drawing from the categories devised in Hanusch and Nölleke’s study (2018) the study then considers if organizational context, types of news organization or gender can be seen to play a role in homophily in political journalists’ retweets and replies, which leads to these research questions:

RQ3:Doshared characteristics such as news organizations; type of news organizations and gender play a role in homophily in retweets?
RQ4: Do shared characteristic ssuch as news organizations; type of news organizations and gender play a role in homophily in replies?
Posted by BipartisanAlliance2 at 11:26 AM 0 comments
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