Evolution of color vision to detect social info: Dichromats may be less accurate at detecting others’ emotional states; dichromats may also display weaker approach/avoidance behavior toward healthy/sick individuals

Social Perception of Facial Color Appearance for Human Trichromatic Versus Dichromatic Color Vision. Christopher A. Thorstenson, Adam D. Pazda, Andrew J. Elliot. Personality and Social Psychology Bulletin, April 13, 2019. https://doi.org/10.1177/0146167219841641

Abstract: Typical human color vision is trichromatic, on the basis that we have three distinct classes of photoreceptors. A recent evolutionary account posits that trichromacy facilitates detecting subtle skin color changes to better distinguish important social states related to proceptivity, health, and emotion in others. Across two experiments, we manipulated the facial color appearance of images consistent with a skin blood perfusion response and asked participants to evaluate the perceived attractiveness, health, and anger of the face (trichromatic condition). We additionally simulated what these faces would look like for three dichromatic conditions (protanopia, deuteranopia, tritanopia). The results demonstrated that flushed (relative to baseline) faces were perceived as more attractive, healthy, and angry in the trichromatic and tritanopia conditions, but not in the protanopia and deuteranopia conditions. The results provide empirical support for the social perception account of trichromatic color vision evolution and lead to systematic predictions of social perception based on ecological social perception theory.

Keywords: trichromatic, color vision, social perception, evolution, face color


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The human face is a wellspring of social information; we can make rapid judgments about a wide range of social characteristics (e.g., sex, race, age, attractiveness, health, emotion) based on only a brief exposure to facial stimuli (Weisbuch & Ambady, 2011). Although a majority of traditional social psychological research has focused on assessing how these judgments influence downstream phenomena (e.g., stereotyping and behavior), only recently have researchers focused on elucidating the lower level perceptual mechanisms that produce these judgments in the first place (Freeman & Ambady, 2011; Oosterhof & Todorov, 2008). An emerging line of research has demonstrated that one such perceptual mechanism that can independently influence a range of social judgments is facial color appearance (for reviews, see (Rowland & Burriss, 2017; Stephen & Perrett, 2015; Thorstenson, 2018). This work suggests that human color vision plays a key role in social perception processes. In the current article, we briefly review theoretical accounts of human color vision evolution, including a recent account driven by social evolutionary considerations. We then overview the existing literature on the role of facial color appearance in the expression and perception of social characteristics (i.e., attractiveness, health, and emotion), grounded in an ecological theory of social perception (Zebrowitz-McArthur & Baron, 1983). Finally, we report two experiments that provide an empirical test of the social evolutionary account of human color vision.

Typical human (and most primate species) color vision is considered trichromatic, meaning we possess three distinct classes of wavelength-sensitive photoreceptive cells called cone photorecepters, or cones, that allow us to discriminate chromatic colors across the visible spectrum. These cones are distinguished as short wavelength (S; with peak sensitivity at ~430 nm), medium wavelength (M; with peak sensitivity at ~535 nm), and long wavelength (L; with peak sensitivity at ~562 nm; Jacobs & Deegan, 1999). Whereas most mammalian species possess dichromacy (having one S cone and one M/L cone), trichromacy in humans and most nonhuman primate species evolved when the older M/L cone opsin gene duplicated and diverged into two separate M and L cones (Dulai, von Dornum, Mollon, & Hunt, 1999).

The functional significance of trichromacy evolution is currently under debate. A popular account suggests that trichromacy was selected to aid primates in foraging by facilitating the detection of ripe fruit against green leaves (Allen, 1879; Lucas et al., 2003; Mollon, 1989; Osorio & Vorobyev, 1996; Surridge & Mundy, 2002). While there is support demonstrated for this hypothesis (Bunce, Isbell, Grote, & Jacobs, 2011; Caine & Mundy, 2000; Melin et al., 2009; Osorio, Smith, Vorobyev, & Buchanan-Smith, 2004; Regan et al., 2001; Smith, Buchanan-Smith, Surridge, & Mundy, 2003; Smith, Buchanan-Smith, Surridge, Osorio, & Mundy, 2003; Sumner & Mollon, 2000; Vorobyev, 2004), some ecological studies do not observe a benefit of trichromacy on foraging behavior (Hiramatsu et al., 2008; Vogel, Neitz, & Dominy, 2007). Other theoretical accounts of color vision variation in primates that have received less empirical attention include camouflage detection, predation detection, and nocturnal versus diurnal activity (see Kawamura & Melin, 2017, for a comprehensive review).

Alternatively, a more recent functional account posits that trichromacy may have been selected by social evolutionary pressures (Changizi, 2010; Changizi & Shimojo, 2011; Changizi, Zhang, & Shimojo, 2006). Specifically, this account suggests that the divergence of M and L cones allows for the optimal detection of socially relevant skin color appearance fluctuations in others. Changizi and colleagues (2006) note that changes in dermal hemoglobin oxygenation and concentration lead to predictable changes in the spectral reflectance (and consequently visible color) of skin. Increases in hemoglobin oxygenation heighten relative L-cone to M-cone activation, resulting in redder skin appearance (while decreases in hemoglobin oxygenation produce the opposite, resulting in greener skin appearance). Increases in hemoglobin concentration tend to increase M- and L-cone activation relative to the S cone, resulting in blue skin appearance, whereas decreases in hemoglobin concentration produce the opposite, resulting in yellow skin appearance (see also Thorstenson, 2018 for a review). Importantly, Changizi and colleagues (2006) demonstrated that M- and L-cone sensitivities in trichromats are situated in the visible spectrum such that they are able to optimally detect these skin color appearance fluctuations. This corre-spondence, between the spectral sensitivity of trichromatic photoreceptors and spectral fluctuations of skin enduring transient hemoglobin changes, presumably enables particu-lar sensitivity to discriminate socially relevant physiologi-cal conditions (e.g., emotional states, sexual signals, and threat displays). It has also been noted that trichromatic primates tend to be bare-faced, allowing rapid access to visual skin color appearance modulations. See Figure 1 for an illustration of the spectral characteristics of human skin and trichromatic photoreceptors. While there is some recent work supporting this hypothesis for viewing nonhuman pri-mate targets (Hiramatsu, Melin, Allen, Dubuc, & Higham, 2017) research in this area is still sparse and has yet to be conducted using human targets.

An ecological theory of social perception holds that social perception processes serve an adaptive function (Zebrowitz, Bronstad, & Montepare, 2011; Zebrowitz-McArthur & Baron, 1983). Perception facilitates goal attainment and species propagation by informing behavior (Gibson, 1979). This ecological approach to social perception assumes that (a) the external environment provides information to guide biologically and socially functional behaviors, and (b) the success-ful transfer of this information relies on a compatibility between a signal (stimulus information) and the perceiver (perceptual system). In the current investigation, we focus on the stimulus information (facial color expression) and the perceptual system (facial color perception) involved in social processes related to evaluation of attractiveness, health, and emotion. We chose to focus on these evaluations because they represent interpersonally important perceptions that shape social interaction and decision making. For instance, perceptions of attractiveness and health guide mating deci-sions because they provide an indicator of overall mate quality and reproductive potential (Etcoff, 1999; Perrett, 2010; Rhodes et al., 2007; Weeden & Sabini, 2005). Similarly, perceptions of emotion (e.g., anger) inform situational context (e.g., dominance, hostility) and guide behavior (e.g., avoidance; Marsh, Adams, & Kleck, 2005).

Indeed there is evidence that skin color appearance subtly undergoes change as an inevitable consequence of socially relevant states. In nonhuman primates, female skin color appearance becomes redder throughout the ovulatory ycle, when sexual cues afford the most significant reproductive consequences (Bielert, Girolami, & Jowell, 1989; Deschner, Heistermann, Hodges, & Boesch, 2004; Dixson, 1983; Gerald, 2003; Setchell & Wickings, 2004; Setchell, Wickings, & Knapp, 2006; Waitt, Gerald, Little, & Kraiselburd, 2006). Skin color appearance in male nonhu-man primates also influences female preferences by signal-ing elevated testosterone (Rhodes et al., 1997; Waitt et al., 2003). In addition, there is evidence that the same skin color appearance modulations occur in human females (Burriss et al., 2015; Edwards & Duntley, 1949; B. C. Jones et al., 2015; McGuiness, 1961; Oberzaucher et al., 2012; Snell & Turner, 1966; van den Berghe & Frost, 1986) and possibly males (due to elevated testosterone; Miller & Maner, 2010). Furthermore, skin color appearance undergoes change as a consequence of physiological states related to health, includ-ing skin vascularization (Changizi & Shimojo, 2011; Charkoudian, 2003; Henderson et al., 2017; Panza, Quyyumi, Brush, & Epstein, 1990; Ponsonby, Dwyer, & Couper, 1997; Sibenge & Gawkrodger, 1992; Wilkin, 1994), bilirubin (Knudsen & Brodersen, 1989), melanin (Stamatas, Zmudzka, Kollias, & Beer, 2004; Zonios, Bykowski, & Kollias, 2001) and carotenoids (Alaluf, Heinrich, Stahl, Tronnier, & Wiseman, 2002; Coetzee & Perrett, 2014; Tan, Graf, Mitra, & Stephen, 2015, 2017; Whitehead, Re, Xiao, Ozakinci, & Perrett, 2012). Finally, there is a sizable litera-ture examining the physiological correlates of experiencing various emotion states, which can then be used to predict how skin color appearance likely changes with respect to these emotions (see Thorstenson, 2018; Thorstenson, Elliot, Pazda, Perrett, & Xiao, 2018, for reviews).



Discussion: [...] Although the prevalence of dichromatic indi-viduals in the general population is quite low (between 2% and 8% of males and approximately 0.4% of females have a red-green color deficiency, and approximately 0.002% of both males and females have a blue-yellow color defi-ciency; Birch, 2012; Simunovic, 2010), these findings raise the possibility that certain color deficiencies exhibit less informed decision making in the social domain as a consequence of systematic misperception. For example, dichromats may be less accurate at detecting others’ emo-tional states, especially when facial expressions can be controlled (e.g., an angry person can maintain a neutral expression, but will still experience facial flushing). This may have problematic behavioral implications, such as failing to avoid someone with a flaring temper and a straight face. Dichromats may also display weaker approach/avoidance behavior toward healthy/sick individuals, and in the medical domain, it has been noted that dichromatic clinicians have significant difficulty in assess-ing clinically relevant skin color modulations (Changizi & Rio, 2010). Although empirical investigations into these possibilities would be difficult due to the relatively low prevalence of dichromats, they would be extremely informative nonetheless. [...]

The proportion of male students who reported having sexual intercourse before age 13 years varied from 5% (San Francisco) to 25% (Memphis, TN); elevated rates among black and Hispanic males

Prevalence of Sexual Initiation Before Age 13 Years Among Male Adolescents and Young Adults in the United States. Laura D. Lindberg, Isaac Maddow-Zimet, Arik V. Marcell. JAMA Pediatr. April 8, 2019. doi:10.1001/jamapediatrics.2019.0458

Key Points

Question: Does the prevalence of sexual initiation before age 13 years among males in the United States vary by race/ethnicity, location, and socioeconomic status?

Findings: This cross-sectional study of 19 916 male high school students and 7739 males aged 15 to 24 years found substantial variation in the rates of sexual onset before 13 years of age across metropolitan areas and by race/ethnicity, with rates as high as 28% among non-Hispanic black males in Memphis, Tennessee.

Meaning: Variation in timing of sexual initiation before age 13 years may have implications for the provision of early, inclusive, and comprehensive sex education as well as sexual and reproductive health care to male children and adolescents.

Abstract
Importance: Despite similar sexual activity rates among male and female adolescents, males are more likely to have their first sexual intercourse before age 13 years. The developmental needs and pathways to healthy trajectories for young males remain unknown.

Objective: To examine the prevalence of sexual intercourse before age 13 years among male adolescents; the variation by race/ethnicity, location, and maternal educational level; and the wantedness of this first sexual experience.

Design, Setting, and Participants: This cross-sectional analysis was conducted from September 2017 to June 2018, using pooled 2011, 2013, and 2015 data from the school-based Youth Risk Behavior Surveillance System (YRBSS) and the 2006 to 2015 data of males aged 15 to 24 years from the household-based National Survey of Family Growth (NSFG). The percentage of males reporting sexual onset before age 13 years was estimated using survey-weighted logistic regression to test for differences by race/ethnicity within each national survey and within metropolitan areas (for YRBSS, high school and middle school samples). Among NSFG survey respondents, differences in wantedness of first sexual intercourse by age at first sexual intercourse were examined, along with the associations between sexual initiation and socioeconomic covariates.

Main Outcomes and Measures: Sexual onset before age 13 years.

Results: Data from a total of 19 916 male high school students (from YRBSS) and 7739 males aged 15 to 24 years (from NSFG) were included in the analysis. The sample was largely composed of non-Hispanic white males: 8789 (57.1%) from the YRBSS and 3737 (58.0%) from the NSFG. Sexual onset before age 13 years was reported nationally by 7.6% (95% CI, 6.8%-8.4%) of male high school students and 3.6% (95% CI, 3.0%-4.2%) of males aged 15 to 24 years. The proportion of male students who reported having sexual intercourse before age 13 years varied across metropolitan sites, from 5% (95% CI, 4%-7%) in San Francisco, California, to 25% (95% CI, 23%-28%) in Memphis, Tennessee, with elevated rates among non-Hispanic black and Hispanic males in most metropolitan areas. In the NSFG data set, respondents whose mothers had a college degree or higher educational level were statistically significantly less likely (OR, 0.31; 95% CI, 0.19-0.49) to report having sexual intercourse before age 13 years compared with those whose mothers did not have a college degree. Among males who reported having their first sexual experience before age 13 years, 8.5% (95% CI, 3.8%-17.8%) described their first sexual intercourse as unwanted.

Conclusions and Relevance: Rates of sexual onset before age 13 years among young males varied by race/ethnicity, location, and maternal educational level, presenting important implications for the provision of early, inclusive, and comprehensive sex education and sexual and reproductive health care to male children and adolescents.

Introduction

First sexual intercourse marks an important transition in an individual’s life,1 and early adolescence is a critical developmental period when experimentation with sexual feelings and behaviors often begins.2,3 During these formative years, expectations to adhere to gender roles and norms intensify. The Centers for Disease Control and Prevention’s Youth Risk Behavior Surveillance System (YRBSS) tracks sexual intercourse before age 13 years as a core surveillance metric and finds that males are more than twice as likely as females to experience first sexual intercourse before age 13 years.4 Sex education guidelines recommend providing children with comprehensive sex education starting at least by kindergarten, and clinical care guidelines recommend clinicians set time alone with young patients to address confidential care inclusive of sexual health starting during early adolescence.5,6 However, most males start having sex before receiving sex education, and the quality of sexual health care delivery to male adolescents is poor.7-9

Estimates of young males’ transition to first sexual intercourse do not examine the prevalence of sexual activity in early adolescence across the intersecting demographics of sex, race/ethnicity, and location, likely missing important variations.10-12 A nationally representative study of sexual behavior reports it as “rare” among those 12 years and younger.13 Yet this conclusion may miss subgroups of males for whom sexual initiation before age 13 years is more common. Given the higher prevalence of first sexual intercourse before age 13 years among males compared with females, understanding the variation in the timing of sexual onset among adolescent males in the United States is critical to supporting their healthy sexual development.

Males’ experiences with regard to emergent manhood and sexuality are shaped by dimensions of masculinity, race/ethnicity, socioeconomic status, and location. Broad cultural scripts about masculinity and sex hold that men should start having sex early and have sex often.14 For young men of color, particularly black males, racist stereotypes of hypermasculinity may also contribute to expectations of early sexual initiation.15-17 Yet research highlights that males in early and middle adolescence do not necessarily follow such scripts and a later transition to first sexual intercourse may be valued.18-22 Understanding males’ wantedness of the sexual experience may be particularly important for interpreting early sexual activity.23,24

Aspects of adolescents’ communities may also be factors in the transition to first sexual intercourse.25-28 Cultural norms and values associated with masculinity may differ across communities.29 Some studies have found differences in the timing of first sexual intercourse between urban and rural settings.30,31 Even across specific urban areas, young men’s experiences may vary.

The current study examined the prevalence of sexual initiation before age 13 years among adolescent males in the United States and the variation in the timing of their sexual initiation by race/ethnicity, location, and maternal educational level and by their characterization of the wantedness of this first sexual experience. Race/ethnicity, socioeconomic status, and location are not the only factors in the timing of first sexual intercourse, but they inform the context in which these experiences and other correlates occur. We used 2 complementary large-scale representative survey systems to assess the timing of sexual onset among adolescent males in the United States, examine key sociodemographic correlates, and consider how reporting issues may affect estimates.

Evidence from online dating sites suggests that most users behave strategically: they remain silent about their political attitudes, more willing to divulge their weight than their politics

From 2017: The Moderating Effects of Marriage Across Party Lines. Shanto Iyengar, Tobias Konitzer. 2017. https://pdfs.semanticscholar.org/a55b/50f3de44529ee301c662aa42fb244e4ab992.pdf

“The Democrats, wherever you find ’em – in the media, think tanks, don’t care whereyou find ’em – they’re being consumed by it, folks. Theyre literally being eaten alive withan irrational, raw hatred.” – Rush Limbaugh, May 10, 2017.

In the aftermath of the 2016 election, the American electorate is hyperpolarized. Animustoward the out party is at an historic high. For the first time on record, the most frequentlyregistered feeling thermometer score for the opposing party (e.g. Democrats’ rating of theRepublican Party and vice-versa) in the 2016 American National Election Study was at theminimum, i.e. zero. Other indicators are similarly skewed toward the extremes. PresidentTrump’s approval drops precipitously from 80 percent among Republicans to under tenpercent for Democrats. Some six times as many Democrats than Republicans believe thatthe Trump campaign colluded with the Russians to sway the election (Washington Post Poll,April 26, 2017). Hostility directed at out groups is a fundamental barometer of group polarization. Classic studies on social distance (Bogardus, 1925), and the sense of social identity (Tajfel, 1970;Tajfel and Turner, 1979) have established that diverging sentiment for in- and out-groupmembers is inevitable. Group polarization defined in terms of differential affect for the inand out group occurs even when the basis for group affiliation is trivial and completelyunrelated to group interests.In the context of American politics, affective polarization deriving from political partyaffiliation is well documented, in stark contrast to ideological polarization, where the evidenceis mixed (compare Abramowitz 2010 with Fiorina, Abrams and Pope 2005). As for partisanaffect, data from the American National Election Surveys dating to the mid-1980s showsthat Democrats and Republicans not only increasingly dislike the opposing party, but alsoimpute negative qualities to its supporters (Iyengar, Sood and Lelkes, 2012).Out-group prejudice based on party identity exceeds the comparable bias directed atracial, religious, or cultural out groups (Muste, 2014; Iyengar and Westwood, 2015). Partisan2 affect has strengthened to the point where party identity is now a litmus test for interpersonalattraction. People prefer to associate with fellow partisans and are less trusting of partisan opponents (Iyengar and Westwood, 2015; Westwood et al., 2017). The most vivid evidence of increased social distance across the party divide concerns inter-party marriage. In the early 1960s, the percentage of partisans expressing concern over the prospect of their son or daughter marrying someone from the opposition party was in the single digits, but some forty-five years later it had risen to more than twenty-five percent (Iyengar, Sood and Lelkes,2012). Data from surveys of married couples, online dating sites, and national voter files confirmthat partisanship has become a key attribute underlying the selection of long-term partners (Huber and Malhotra, 2017; Iyengar, Konitzer and Tedin, 2017). Among recently marriedcouples in 1973, only 54 percent shared the same party affiliation. Forty years later, partisan agreement among this group had risen to 74 percent (Iyengar, Konitzer and Tedin, 2017).Survey results standing alone may not be the most meaningful measure of increasingpartisan animus. The expression of hostility based on partisanship is not subject to thesame social taboos as hostility based on other salient social divides (racial, religious, orethnic). Instead, hostility directed at the out party is deemed acceptable, even appropriate.Therefore, survey data could artificially elevate the significance of the partisan divide overother significant cleavages. But, importantly, there is considerable evidence of increasedpartisan animus outside the survey realm; this evidence is not subject to normative, consciousrestraints based on political correctness. Using a version of the Implicit Association Test,Iyengar and Westwood (2015) demonstrated that implicit bias directed at the out partyexceeded comparable bias based on race. They also showed that behavioral discriminationagainst partisan opponents in a variety of contexts exceeded discrimination based on othergroup cues, most notably, race. What explains the dramatic increase in affective polarization over the past few decades?3

The period in question (1985-2015) coincides with any number of major societal changes,including the vastly increased ethnic and cultural diversity of the population, the migration ofwhites from urban areas to the suburbs, the emergence of the South as a staunch Republicanregion, and the politicization of evangelical Christians. One possible explanation, sometimesreferred to as ”sorting,” is the increasing convergence of multiple salient social identities which reinforce each other. In other words, Democrats and Republicans differ not only int heir politics, but also in their ethnic, religious, gender, cultural, and regional identities.Sorting leads to overlapping group memberships and the increasing partisan homogeneity of primary and secondary groups is a further contributor to polarization. Family and kinship networks – key influences over the development of political attitudes – provide few opportunities for meaningful and long-term personal contact across party lines. As we notebelow, even at the level of secondary groups, defined on the basis of occupation, religion, orplace of residence, partisan homophily is extensive (for evidence on occupational similarity inpartisan affiliation, see Bonica, Chilton, and Sen 2016; the geographic sorting of the nation into Republican and Democratic enclaves is documented most recently in Chen and Cottrell2016 and Chen, Rodden et al. 2013.We investigate the role of interpersonal relations as a potential contributor to partisanpolarization. We focus on the family, the most important agent of political socialization.Comparing surveys of spouses conducted in the 1960s, the 1990s and the current era, wedemonstrate that over time, spousal disagreement – although clearly becoming less frequent– can act as a brake on polarization by fostering less hostile attitudes toward partisan opponents. The more heterogeneous the household, the less polarized the individual members.We replicate these survey findings a secondary analysis of a set of 2015 and 2016 field experiments that targeted registered voters in multiple states. Participants in these experiments completed surveys that included feeling thermometers and other measures of partisan affect. Because the surveys sampled multiple family members living at the same address, we can4 investigate the effects of household agreement on partisan affect. In fact, the data from these field studies converge with the surveys of spouses; mixed-party households are significantly less polarized.


Discussion

In our experience, it is unusual to observe differences of this scale in the behavioralsciences. In several instances, the order of magnitude of the difference in polarization between similar and dissimilar family pairs exceeded 200 percent! Even more unusual is thefact that our results survived multiple replications spanning different research designs, elec-toral contexts, and survey indicators of partisan affect. While we acknowledge the causalthreat posed by selection effects, i.e. potential spouses with polarized attitudes selectinginto homogeneous marriages, the matching analysis does little to bolster this alternativeexplanation.9In total, the story line is unmistakable; political disagreement within familyrelations discourages extreme evaluations of in and out groups, thus alleviating polarization.Of course, documenting the powerful effects of family diversity on partisan affect begsthe question of what exactly is the mechanism through which exposure to disagreementmoderates individuals’ evaluations of the parties. One possibility is that domestic tranquilityrequires the expression of opinions that respect the positions of significant others, makingindividuals more tolerant and accepting of disagreement. Alternatively, as suggested by theclassic “contact” hypothesis (Allport, 1954; Pettigrew, 1998, 1997), valued inter-personalrelations that cut across the party divide may serve to weaken negative stereotypes of theout group; for contrary evidence, however, see Enos (2014). Yet another possible mechanism,also suggested by previous research (Mutz, 2006), is that inter-personal contact heightensawareness of the values and arguments underlying the preferences of out party supporters,making the party appear less threatening. All these mediating mechanisms appear to becontingent on exposure to the opponent’s point of view; we would anticipate, accordingly,that the effects of family diversity on partisan evaluations will be enlarged when familymembers frequently converse about public affairs.While our results imply that cross-party family ties are a potential antidote to polariza-tion, it is important to keep in mind that this ”treatment” only impacts a relatively smallswath of American partisans. The most recent data on inter-marriage indicate that less9Although while matching might tackle the selection problem more appropriately then parametric re-gression analyses, we note that the identification assumption remains selection-on-observables.23 than twenty percent of partisans are exposed to disagreement. The likelihood that parti-sans’ children will diverge on political grounds is similarly remote; in a 2015 survey, 74.2percent of parent-offspring dyads agreed on their partisan affiliation (Iyengar, Konitzer andTedin, 2017). The critical question, therefore, concerns the ways in which society can lowerthe barriers to social exchange across the party divide.In theory, one solution to the problem of politically homogeneous networks is to weakenindividuals’ ability to signal their political affiliation. If all participants in the marriageor dating market were ”blind” to partisan affiliation, partner selection would be drivenprimarily by non-political attributes. Rational ”sellers” should deliberately conceal theirpolitical views when seeking out potential mates. In fact, the evidence from online datingsites suggests that most users of these sites behave strategically: they choose to remainsilent about their political attitudes. Research into the content of online daters’ personalprofiles shows that less than fifteen percent of online daters provided information abouttheir “political interests” and when they did reference politics in their personal profile, theyidentified themselves as “middle of the road” (Klofstad, McDermott and Hatemi, 2012). This same study shows, revealingly, that online daters are more willing to divulge their weightthan their political preferences.Online databases provide opportunities for people to sort into relationships on the basisof attributes extraneous to partisanship. Since some twenty percent of single individualsreport using online dating sites, technology might be a tool for dampening polarization.Yet, as Huber and Malhotra (2017) have recently demonstrated, individuals manage tounearth information about their prospective partner’s political views despite the lack oftransparency; so much so, that political ideology is the strongest predictor of successfulonline match making. The motivation to find a politically compatible mate is sufficient toovercome online daters’ lack of transparency about their politics.In closing, our results show that partisan attitudes are distinctly less polarized when close inter-personal ties are not based on the criterion of political similarity. For those seekingto reduce animus and conflict across party lines, it is important to design meeting placesor platforms on which people become less focused on questions of political identity as animportant basis for their inter-personal relations.

Under What Conditions Does Prosocial Spending Promote Happiness?

Lok, Iris, and Elizabeth W. Dunn. 2019. “Under What Conditions Does Prosocial Spending Promote Happiness?” PsyArXiv. April 12. doi:10.31234/osf.io/9bpg5

Abstract: Under what conditions does prosocial spending promote happiness? In a series of well-powered and pre-registered experiments, the present research revisited the role of impact, social connection, and perceived choice in maximizing the emotional benefits of spending money on others. In two exploratory studies, we found that happy (vs. less happy) prosocial spending experiences were marked by higher levels of impact, social connection and perceived choice (Study 1a and 1b). Consistent with these initial findings, three pre-registered studies revealed confirmed that spending money on others was particularly rewarding when people were able to see the difference their generosity made (Study 2); when they felt a sense of social connection to the person or cause they were helping (Study 3); and when they felt that the decision to help was freely chosen (Study 4). Together, our findings corroborate previous research on impact, social connection and perceived choice, and highlight the importance of considering these key variables when evaluating old and new evidence on prosocial spending on happinessthe emotional benefits of prosocial spending. In addition, our findings suggest that  the present work urges charitable organizations and policymakers should to review their current solicitation strategies and pay more attention to people’s sense of impact, connection and choice when seeking charitable donations.