These results indicate that despite dexterity and visual constraints, pigs have the capacity to acquire a joystick-operated video-game task

Acquisition of a Joystick-Operated Video Task by Pigs (Sus scrofa). Candace C. Croney1 and Sarah T. Boysen. Front. Psychol., February 11 2021. https://doi.org/10.3389/fpsyg.2021.631755

Abstract: The ability of two Panepinto micro pigs and two Yorkshire pigs (Sus scrofa) to acquire a joystick-operated video-game task was investigated. Subjects were trained to manipulate a joystick that controlled movement of a cursor displayed on a computer monitor. The pigs were required to move the cursor to make contact with three-, two-, or one-walled targets randomly allocated for position on the monitor, and a reward was provided if the cursor collided with a target. The video-task acquisition required conceptual understanding of the task, as well as skilled motor performance. Terminal performance revealed that all pigs were significantly above chance on first attempts to contact one-walled targets (p < 0.05). These results indicate that despite dexterity and visual constraints, pigs have the capacity to acquire a joystick-operated video-game task. Limitations in the joystick methodology suggest that future studies of the cognitive capacities of pigs and other domestic species may benefit from the use of touchscreens or other advanced computer-interfaced technology.

Discussion

Overall, all pigs performed significantly above chance on one-walled targets, which indicates that, to some extent, all acquired the association between the joystick and cursor movement. That the pigs achieved the level of success they did on a task that was significantly outside their normal frame of reference in itself remarkable, and indicative of their behavioral and cognitive flexibility. Their high level of social motivation to perform the task was also noteworthy. Although food rewards associated with the task were likely a motivating factor, the social contact the pigs experienced with their trainer also appeared to be very important. Occasionally, during some sessions, equipment failures resulted in non-reward following correct responses. On these occasions, the pigs continued to make correct responses when rewarded only with verbal and tactile reinforcement from the experimenter, who was also their primary caretaker. Additionally, during times when the task demands seemed most challenging for the pigs, and resulted in reluctance to perform, only verbal encouragement by the experimenter was effective in resuming training. This may have been due to the strong bond the pigs developed with the experimenter during training, which would support the assertion of Boysen (1992) that the human-animal bond is a crucial element in the success of animals used in studies of comparative cognition.

It should be noted that despite performing above chance on the SIDE task, even the pig that performed best did not approach the level attained by non–human primates that acquired the task after a comparable number of trials (see Hopkins et al., 1996). Indeed, none of the pigs was able to meet the criteria of Hopkins et al. (1996) for demonstrating motoric or conceptual acquisition of the SIDE task. There are several possible explanations for the pigs’ failure to meet they criteria. First, they were established for dexterous primates (rhesus monkeys and chimpanzees); although no clear rationale was provided for their adoption. Thus, it was difficult to know how to adapt those criteria for pigs, taking into account their more limited perceptual and motor capabilities, which clearly differ from primates. For example, the visual demands of the task may have been particularly problematic for the pigs, since we had previously established that all four subjects were far-sighted. As sufficient visual capability is a prerequisite for successful completion of a joystick-operated-video game task, and despite attempts to position the computer monitor appropriately, it is impossible to know how well the pigs were able to see, and subsequently correctly discriminate between targets. Furthermore, because of the positioning of the pigs’ eyes relative to their snouts, they were often forced to watch the screen prior to moving the joystick, and then check their progress after cursor movement was initiated. This artifact of the pigs’ anatomy likely contributed to some of their errors because in order to succeed, they not only needed dexterity and conceptual understanding of the task, but perhaps also short-term or working memory (which is not well understood in pigs) of the target position locations.

In addition, the pigs’ limited dexterity no doubt constrained their performance. Because the joystick-operated video-task paradigm was initially designed for use by non-human primates with great manual dexterity, modifications to the equipment were necessary so that the pigs could use their snouts to manipulate the joystick. However, the pigs’ ability for such manipulation was restricted to their normal range of head and neck movements. This limitation appeared particularly troublesome for the Yorkshire pigs whose larger size also constrained their ability to reposition themselves as needed to contact targets located in the horizontal plane. Thus, it was not surprising that the Yorkshire pigs performed better on vertical plane movements, which are more frequently seen in their normal behavioral repertoire during routine activities such as rooting. In fact, when faced with left or right targets, the Yorkshire subjects were often observed to alter their stance so that they were parallel to the computer screen. This way, they could approach horizontal targets in the same way they did for those in the vertical plane. Because of their small size, the micro pigs were better able to reorient themselves as needed to view the computer monitor and complete horizontal plane movements. This flexibility likely resulted in better performance in both planes and may have contributed to their superior performance compared to the Yorkshire subjects. Ebony and Ivory’s smaller size also enabled them to be maintained in the laboratory for a much longer period for training and testing (15 months) than the Yorkshire pigs. Thus, they were afforded the opportunity to continue training, thereby contributing to their improved performance on the SIDE task. Consequently, their terminal performance was much better than the Yorkshire pigs that were trained for only 10 weeks on the same task.

Additional problems that may have been attributable to dexterity limitations were observed when the pigs were unable to completely move the cursor toward a target wall and finish the trial, simply because of the angle at which the cursor approached the target. On these occasions, the pigs often nosed the joystick to move the cursor back out of the target wall and then altered the angle at which they approached the target. However, in doing so, they sometimes contacted an incorrect wall, resulting in reduced accuracy on their first cursor attempts. Further, when the pigs were unable to make contact with a horizontal target, they often resorted to strategies that allowed them to move the cursor upward, then down into the correct left or right wall. These responses were consistently observed, particularly for Hamlet and Omelet, who systematically responded with a series of movements that resembled an “inverted v” when faced with right or left targets. The resultant asymmetry in the pigs’ performance relative to target position is similar to that observed in rhesus monkeys (Hopkins et al., 1996). In comparing the performance of rhesus monkeys to chimpanzees on the SIDE task, Hopkins et al. (1996) observed that the monkeys had more difficulty responding to horizontal targets, suggesting that their manipulative behavior was less diverse than chimpanzees. This problem may, in part, explain the pigs’ poor performance relative to primates, as their ability to manipulate objects is significantly less dexterous and flexible.

Response biases can often be inevitable when testing animals, and they emerged during testing with the pigs as well. For example, while Ebony, like all of the subjects, showed some level of side bias (left), he did correctly move the cursor to the right numerous times on all but the one-wall task. As previously noted, these trials created the smallest targets for the pigs. Side bias training was instituted for all pigs manually upon observation of biases because although the software titrated to an easier level of task difficulty if a subject made errors consistently, the program’s random generation of target locations did not facilitate training to overcome bias. This intervention was not successful, however. Learning on manual side-bias training with objects or with the joystick with the computer turned off (necessary given the previously mentioned software limitations) did not appear to generalize to the joystick-operated task. A few explanations for this observation are plausible. First, Ebony may simply have been limited in either or both dexterity and the paw/snout/eye-coordination needed to hit right-sided, one-walled targets. It is also possible that because the video-task apparatus was not centered in the pen due to constraints of the testing space, Ebony’s body positioning to complete such tasks may have further constrained his performance given that additional training did not correct the side-bias problem with the joystick, although it was effective on bias correction using objects (Croney, 1999). It is also possible that some degree of instinctive drift may have impacted his and the other pigs’ performance, especially as the tasks became more challenging and rewards for behaviors performed were reduced due to errors.

An alternative explanation for the difference between the pigs’ and primates’ performance that must be considered is that the pigs may have been unable to fully comprehend the concepts required to perform well on the SIDE task. Difficulties with the conceptual component of the task may have been due, in part, to the spatial discontiguity of the stimulus and response. Meyer et al. (1965) suggested that a primate’s learning efficiency might be impaired when the hand used to execute a response was placed in an area distant from the location of the discriminative stimuli. A similar rationale may have been a factor for the pigs, since the movement of their snouts was some distance from the images displayed on the monitor, and the lateral placement of their eyes may have contributed to a cognitive disconnect between their movements and the resulting changes appearing on the screen.

In addition to the difficulties posed by limited dexterity and vision, several methodological factors may also have impeded the pigs’ performance on the SIDE task. First, because a protocol for testing pigs using the joystick-operated video-game task paradigm had not previously been established, the methods used in the current experiment were exploratory. As such, some changes in procedures and equipment were necessary during the experiment to correct concerns as they emerged. For instance, early design flaws in the joystick apparatus were detected and required correction. Initially, the protective welded plastic area surrounding the joystick was too high and impeded movement of the joystick in all directions. In addition, positioning of the feed delivery tube attached to the automatic dispenser sometimes resulted in failure to deliver rewards to the pigs after correct responses early in training and required correcting. This delay in reinforcement following a correct response may have impeded the animals’ initial learning. Finally, the test pen was designed so that the joystick apparatus was positioned approximately 0.04 m away from the right side of the pen. This initial positioning proved to be significant in that it restricted the pigs’ abilities to stand or move to the right of the joystick.

Initial training procedures also proved to be problematic. One problem in the training process was that the pigs were allowed to work at their own pace, which resulted in a large set of data consisting primarily of four- and three-sided tasks. After the protocol was amended to require performance of a minimum number of two- and one-walled targets during each session, improved performance on these conditions was observed. However, the Yorkshire pigs had been terminated from testing by the time procedures were revised, and thus did not benefit from the revision. Moreover, this change in training made it extremely difficult for the micro pigs to achieve stringent criteria of Hopkins et al. (1996) for all facets of task acquisition.

Taken together, the failure of all subjects to meet the criteria for SIDE task acquisition may reflect the limitations first imposed by procedural methodology issues, and visual and motor skill limitations, rather than learning deficits. Although their performance was limited compared to primates tested, that they were able to perform as successfully as they did on one-walled targets suggests they acquired some important aspects of the task demands. However, it is impossible to determine to what extent their ability to demonstrate conceptual understanding of the SIDE task may have been constrained by their perceptual and motor capacities. Nonetheless, evaluation of their terminal test results showed that all pigs improved their performance with respect to the various target positions. This improvement was particularly noteworthy for the Yorkshire pigs (Hamlet and Omelet), who completed only a few 100 trials in their 10 weeks of training on the task. Furthermore, the high level of performance attained by one of the micro pigs (Ivory), regardless of target position or number of walls, strongly suggests some level of conceptual acquisition of the task.

In summary, the results of the present study underscore the importance of understanding the basic perceptual and motor capabilities of a species prior to developing appropriate methods of testing their cognitive abilities. While the joystick-operated video-game paradigm has proven suitable for testing several species, including monkeys, pigeons, and chimpanzees (Rumbaugh et al., 1989; Washburn et al., 1990; Spetch et al., 1992; Hopkins et al., 1996), it is not optimal for testing the cognitive abilities of pigs, as their performance was clearly hindered by dexterity limitations and visual constraints. Thorough investigations of the pig’s visual and motor capabilities are necessary before their cognitive abilities can be adequately assessed using this or any type of technology. Use of a computer touch screen may better address the problem of limited dexterity and would likely provide a more viable alternative in future computer-interfaced studies of the cognitive abilities of pigs.

We find that sharing personal experiences about a political issue—especially experiences involving harm—help to foster respect via increased perceptions of rationality

Personal experiences bridge moral and political divides better than facts. Emily Kubin et al. Proceedings of the National Academy of Sciences, February 9, 2021 118 (6) e2008389118; https://doi.org/10.1073/pnas.2008389118

Significance: All Americans are affected by rising political polarization, whether because of a gridlocked Congress or antagonistic holiday dinners. People believe that facts are essential for earning the respect of political adversaries, but our research shows that this belief is wrong. We find that sharing personal experiences about a political issue—especially experiences involving harm—help to foster respect via increased perceptions of rationality. This research provides a straightforward pathway for increasing moral understanding and decreasing political intolerance. These findings also raise questions about how science and society should understand the nature of truth in the era of “fake news.” In moral and political disagreements, everyday people treat subjective experiences as truer than objective facts.

Abstract: Both liberals and conservatives believe that using facts in political discussions helps to foster mutual respect, but 15 studies—across multiple methodologies and issues—show that these beliefs are mistaken. Political opponents respect moral beliefs more when they are supported by personal experiences, not facts. The respect-inducing power of personal experiences is revealed by survey studies across various political topics, a field study of conversations about guns, an analysis of YouTube comments from abortion opinion videos, and an archival analysis of 137 interview transcripts from Fox News and CNN. The personal experiences most likely to encourage respect from opponents are issue-relevant and involve harm. Mediation analyses reveal that these harm-related personal experiences increase respect by increasing perceptions of rationality: everyone can appreciate that avoiding harm is rational, even in people who hold different beliefs about guns, taxes, immigration, and the environment. Studies show that people believe in the truth of both facts and personal experiences in nonmoral disagreement; however, in moral disagreements, subjective experiences seem truer (i.e., are doubted less) than objective facts. These results provide a concrete demonstration of how to bridge moral divides while also revealing how our intuitions can lead us astray. Stretching back to the Enlightenment, philosophers and scientists have privileged objective facts over experiences in the pursuit of truth. However, furnishing perceptions of truth within moral disagreements is better accomplished by sharing subjective experiences, not by providing facts.

Keywords: moralitypoliticspoltical tolerancemoral psychologynarrative

Exercise-induced euphoria and anxiolysis are independent of direct occupancy of endogenous μ-opioid receptors binding; endocannabinoids are better candidates than endorphins to explain a runner's high in humans

Exercise-induced euphoria and anxiolysis do not depend on endogenous opioids in humans. Michael Siebers et al. Psychoneuroendocrinology, February 10 2021, 105173. https://doi.org/10.1016/j.psyneuen.2021.105173

Highlights

• Exercise-induced euphoria and anxiolysis are independent of direct occupancy of endogenous μ-opioid receptors binding.

• Running reduces anxiety levels in a human elevated plus-maze.

• Running stimulates the endocannabinoid system.

• Endocannabinoids are better candidates than endorphins to explain a runner's high in humans.

Abstract: A runner's high describes a sense of well-being during endurance exercise characterized by euphoria and anxiolysis. It has been a widespread belief that the release of endogenous opioids, such as endorphins, underlie a runner's high. However, exercise leads to the release of two classes of rewarding molecules, endocannabinoids (eCBs) and opioids. In mice, we have shown that core features of a runner's high depend on cannabinoid receptors but not opioid receptors. In the present study, we aimed to corroborate in humans that endorphins do not play a significant role in the underlying mechanism of a runner's high. Thus, we investigated whether the development of two core features of a runner's high, euphoria and reduced anxiety levels, depend on opioid signaling by using the opioid receptor antagonist naltrexone (NAL) in a double-blind, randomized, placebo (PLA)-controlled experiment. Participants (N=63) exhibited increased euphoria and decreased anxiety after 45 min of running (RUN) on a treadmill in a moderate-intensity range compared to walking (WALK). RUN led to higher plasma levels of the eCBs anandamide (AEA) and 2-arachidonoglycerol (2-AG). Opioid blockade did not prevent the development of euphoria and reduced anxiety as well as elevation of eCB levels following exercise. Moreover, the fraction of participants reporting a subjective runner's high was comparable in the NAL and PLA-treated group. Therefore, this study indicates that the development of a runner's high does not depend on opioid signaling in humans, but makes eCBs strong candidates in humans, as previously shown in mice.

Keywords: Endocannabinoidendorphinrunningexerciseanxietyeuphoria

‘She doesn’t think that happens’: When heterosexual men say no to sex

‘She doesn’t think that happens’: When heterosexual men say no to sex. Joni L  Meenagh. Sexualities, July 6, 2020. https://doi.org/10.1177/1363460720936460

h/t David Schmitt article explores three young people’s experiences of men saying ‘no’ to a woman’s request for sex within an ongoing relationship. In each of these instances the refusal was, to some extent, not respected

Abstract: Dominant understandings of men’s sexuality claim that men are always up for sex; as such, research on heterosexual men’s sexual refusals is sparse. Drawing on interviews conducted with young people (aged 18–23) living in and around Melbourne, Australia, this article explores three young people’s experiences of men saying ‘no’ to a woman’s request for sex within an ongoing relationship. In each of these instances the refusal was, to some extent, not respected. This presents a challenge to men’s masculinity which then needs to be redressed through compensatory manhood acts. This article explores how the truth claims of hegemonic masculinity and the male sexual drive discourse are reproduced through men and women’s social interactions, and unpacks the implications of men’s sexual refusals not being heard for sexual ethics education programmes.

Keywords Hegemonic masculinity, heterosexuality, male sexual drive discourse, sexual ethics, sexual refusals

Discussion and conclusion

Under the male sexual drive discourse men are expected to say yes to sex. Withinheterosexual relationships, women police the boundaries of appropriate masculin-ity. One way they do this is through not ‘hearing’ men’s sexual refusals. This is apotentially volatile position to be in: between feeling like they cannot say no to sexand having their refusal ignored, some men may not get the chance to learn how tonegotiate their own sexual boundaries. This is a problem, given the current pushtowards ‘sexual ethics’ and ‘respectful relationships’ type sexuality education pro-grams in Australia (Carmody, 2013; Fileborn, 2016; Our Watch, 2019).These programs seek to prevent violence against women by instilling in youngpeople an understanding of gendered power dynamics and behavioral tools forpromoting gender equity within their relationships; however, they do not yet go farenough in disrupting traditional gender norms. While these programs are a prom-ising development, research on young people’s experiences with theSex & EthicsViolence Prevention Programindicates that men improved in their understandingsof their partner’s needs, while women improved in caring for themselves(Carmody, 2013; Carmody and Overden, 2013). Looking at post-training feedbackfrom young men, assumptions that men are always up for sex are not challenged; instead, these young men have learned to better temper their sexual ‘drive’(Carmody, 2013).The stories told by John, Ash, and Berry indicate that traditional gendereddiscourses may be reproducing themselves in insidious ways through young peo-ple’s sexual negotiations. While this study reports on a small number of instances,it points to the need to look deeper at what is happening within young people’sromantic and sexual relationships. The sexual refusals discussed here all occurredamidst moments of emotional complexity within their relationships: John waswary of being hurt by Rachel; Ash was upset with his girlfriend’s apparent prior-itization of her career over their relationship; and Dave was trying to move onfrom his relationship with Berry. By requesting sex and ‘ignoring’ their partner’srefusal, these young women exercise power – albeit to limited effect – within theirrelationships. This has important implications for how we understand the gendereddynamics of relationship negotiation, and for promoting ethical frameworks ofsexual negotiation – most notably, that gendered power dynamics are complex andhegemonic norms can resurface in seemingly progressive ways.Sexual ethics education and violence prevention programs need to move beyondthe focus on negotiation based on women’s sexual pleasure and desire (seeCarmody, 2009). We expect women to be able to say both ‘no’ and ‘yes’ to sex,and we need to make this available to men as well. Without challenging anddisrupting the dominant discursive claim that men constantly desire sex andsexual attention, women – whether accidentally or deliberately – upholster themale sexual drive discourse and the gendered norms and double standards thatcome with it. We need to hear men’s stories of not wanting to have sex andunderstand their reasons for saying no in order to open space for more fluidtypes of masculinity to emerge. Without taking men’s experiences into account,we do a disservice to both women and men as we attempt to develop more ethicalsexual subject positions. However, we also need to remember that hegemonic mas-culinity is slippery, and what can seem like a fresh take on gendered norms mayjust be hegemonic masculinity playing out in a different way.

Limitations and directions for future research

This article has provided novel insights into heterosexual men’s experiences ofsaying ‘no’ to sex within their ongoing relationships, however there are anumber of limitations to this analysis. The research this study is drawn fromlooked at young people’s negotiation of their romantic and sexual relationshipsand did not explicitly seek to speak to heterosexual men about their sexual refusals.While the three stories presented here indicate that this is a potentially commonexperience, it is not possible to make inferences about the extent that it occurs.While there is a commonality in how these men then reasserted a more hegemonicmasculinity within their relationships, other men may respond differently – andother women may more readily ‘hear’ their partner’s sexual refusals. This is an arearipe for future research to explore, particularly given the implications for violence prevention programs. The potential for heterosexual men’s sexual refusals to gounheard, and for this to then trigger compensatory manhood acts which reasserttheir dominance, raises a number of questions about how best to work with menandwomen to promote respectful, ethical sexual negotiation.

Contemporary understandings of paleoanthropological data illustrate that the search for a line defining, or a specific point designating, “modern human” is problematic

The ripples of modernity: How we can extend paleoanthropology with the extended evolutionary synthesis. Marc Kissel  AgustÍn Fuentes. Evolutionary Anthropology: Issues, News, and Reviews; February 5 2021. https://doi.org/10.1002/evan.21883

Abstract: Contemporary understandings of paleoanthropological data illustrate that the search for a line defining, or a specific point designating, “modern human” is problematic. Here we lend support to the argument for the need to look for patterns in the paleoanthropological record that indicate how multiple evolutionary processes intersected to form the human niche, a concept critical to assessing the development and processes involved in the emergence of a contemporary human phenotype. We suggest that incorporating key elements of the Extended Evolutionary Synthesis (EES) into our endeavors offers a better and more integrative toolkit for modeling and assessing the evolution of the genus Homo. To illustrate our points, we highlight how aspects of the genetic exchanges, morphology, and material culture of the later Pleistocene complicate the concept of “modern” human behavior and suggest that multiple evolutionary patterns, processes, and pathways intersected to form the human niche.

500 Harlequin romance novel cover images, published from 1953 to 2014: Exploring the interactions among women’s evolved mating behaviors & sociocultural norm changes; increasing explicitness reflects permissiveness shifts

Fisher, M. L., & Meredith, T. (2021). Evolutionary and sociocultural themes in cover art on harlequin romance novels: A temporal analysis. Evolutionary Behavioral Sciences. Advance online publication. https://doi.org/10.1037/ebs0000258

Abstract: We analyzed over 500 Harlequin romance novel cover images, published from 1953 to 2014, to explore the interactions among women’s evolved mating behaviors and sociocultural norm changes. Examination of the covers reveals that over time there was an increasingly intimate focus on the couple (to the exclusion of other individuals), as represented by more reclining poses, physical interactions, and direct eye gazing. We contend, given that women have been the primary consumers of romance novels, that the covers address women’s evolved mate preferences and that the increasing explicitness of the imagery, in terms of sexuality and intimacy, reflects sociocultural shifts in permissiveness. Therefore, Harlequin cover art represents an innovative lens through which to examine both evolutionary and sociocultural forces pertaining to women’s evolved sexuality and mating interests. We discuss ideas for future research such as how the analysis of cover art could provide a case study in evoked cultural behaviors that result from shared psychological mechanisms produced in response to local environmental cues.

About 80% of those with a current sexual or romantic partner engaged in rough sex with them & most who engaged it liked it; bisexual women reported greater frequency & enjoyment, 54% enjoying it "very much"

What Is Rough Sex, Who Does It, and Who Likes It? Findings from a Probability Sample of U.S. Undergraduate Students. Debby Herbenick, Tsung-chieh Fu, Dubravka Svetina Valdivia, Callie Patterson, Yael Rosenstock Gonzalez, Lucia Guerra-Reyes, Heather Eastman-Mueller, Jonathon Beckmeyer & Molly Rosenberg. Archives of Sexual Behavior, Feb 9 2021. https://rd.springer.com/article/10.1007/s10508-021-01917-w

Abstract: Using data from an undergraduate probability sample, we aimed to: (1) describe the prevalence and demographic characteristics of students who reported having engaged in rough sex with their current partner; (2) assess which sexual behaviors students consider to be rough sex; (3) describe the frequency with which participants report engaging in rough sex as well as their reports of initiating and liking rough sex, in relation to gender and sexual identity; and (4) examine predictors of rough sex frequency. Participants were 4998 students randomly sampled from a large Midwestern university who completed a confidential Internet-based survey (2453 women, 2445 men, 41 gender non-binary, 36 transgender or other gender non-conforming identities). Within these, 1795 individuals who reported a romantic/sexual partner of at least 3 months responded to questions about engaging, liking, and initiating rough sex. The most common behaviors participants considered to be rough sex were choking, hair pulling, and spanking. Transgender and gender non-binary students more often endorsed behaviors as rough sex. Also, rough sex was conceptualized as multidimensional, with one cluster being more consistent with earlier conceptualizations of rough sex (e.g., hair pulling, spanking) and the second cluster including behaviors such as choking, slapping, punching, and making someone have sex. About 80% of those with a current sexual or romantic partner engaged in rough sex with them and most who engaged it liked it. Bisexual women reported greater rough sex frequency and enjoyment (54.1% indicated enjoying it “very much”). Implications for sexuality research and education are discussed.

There is little reason to think that accommodative monetary policy plays a significant role in reducing racial inequities in the way often discussed; on the contrary, it may well accentuate inequalities for extended periods

Bartscher, Alina K. and Kuhn, Moritz and Schularick, Moritz and Wachtel, Paul, Monetary Policy and Racial Inequality (January 2021). FRB of New York Staff Report No. 959, https://ssrn.com/abstract=3775699

Abstract: This paper aims at an improved understanding of the relationship between monetary policy and racial inequality. We investigate the distributional effects of monetary policy in a unified framework, linking monetary policy shocks both to earnings and wealth differentials between black and white households. Specifically, we show that, although a more accommodative monetary policy increases employment of black households more than white households, the overall effects are small. At the same time, an accommodative monetary policy shock exacerbates the wealth difference between black and white households, because black households own less financial assets that appreciate in value. Over multi-year time horizons, the employment effects are substantially smaller than the countervailing portfolio effects. We conclude that there is little reason to think that accommodative monetary policy plays a significant role in reducing racial inequities in the way often discussed. On the contrary, it may well accentuate inequalities for extended periods.

Keywords: monetary policy, racial inequality, income distribution, wealth distribution, wealth effects

JEL Classification: E40, E52, J15

Gratitude facilitates obedience: New evidence for the social alignment perspective

Tong, E. M. W., Ng, C.-X., Ho, J. B. H., Yap, I. J. L., Chua, E. X. Y., Ng, J. W. X., Ho, D. Z. Y., & Diener, E. (2020). Gratitude facilitates obedience: New evidence for the social alignment perspective. Emotion, Feb 2021. https://doi.org/10.1037/emo0000928

h/t David Schmitt  worm-grinder studies...the saga continues

Abstract: We report four studies that tested the hypothesis that gratitude increases obedience. Four experimental studies (N = 623) found that participants who were induced to feel gratitude obeyed to a greater extent a command to grind worms in a grinder than those feeling neutral. These novel findings demonstrate that gratitude can encourage obeying instructions to exact physical harm, violating moral principles of care. Grateful participants obeyed both benefactors and nonbenefactors. Induced happiness and admiration did not produce the same effect and we found evidence using a manipulation-of-mediator method that the need for social harmony played a mediating role. The findings suggest that gratitude can make a person more vulnerable to social influence, including obeying commands to perform an ethically questionable act.

By making information retrievability salient, Internet search reduces the likelihood of information being stored in memory; & searching online leads to the misattribution of online information to internal memory, masking learning deficits

Information without knowledge: the effects of Internet search on learning. Matthew Fisher, Adam H. Smiley & Tito L. H. Grillo. Memory, Feb 8 2021. https://doi.org/10.1080/09658211.2021.1882501

Abstract: The Internet has radically shifted how people access information. Instead of storing information internally, increasingly, people outsource to the Internet and retrieve it when needed. While this is an efficient strategy in many ways, its downstream consequences remain largely unexplored. This research examines how accessing online information impacts how people remember information in a learning context. Across five experiments, participants studied for a quiz either by searching online to access relevant information or by directly receiving that same information without online search. Those who searched the Internet performed worse in the learning assessment, indicating that they stored less new knowledge in internal memory. However, participants who searched the Internet were as confident, or even more confident, that they had mastered the study material compared to those who did not search online. We argue that, by making information retrievability salient, Internet search reduces the likelihood of information being stored in memory. Further, these results suggest that searching online leads to the misattribution of online information to internal memory, thus masking the Internet-induced learning deficits.

KEYWORDS: Memorymetacognitionlearningtechnology & cognition

People can know how their relationship partners make them feel, but, because they often desire to see their relationship partners in a positive light, they may avoid accessing these feelings

Hicks, L. L., McNulty, J. K., Faure, R., Meltzer, A. L., Righetti, F., & Hofmann, W. (2021). Do people realize how their partners make them feel? Relationship enhancement motives and stress determine the link between implicitly assessed partner attitudes and relationship satisfaction. Journal of Personality and Social Psychology, 120(2), 335–369. https://doi.org/10.1037/pspi0000247

Abstract: Do people realize the evaluative feelings that are spontaneously activated by their partner? If so, do they use those evaluations when judging their romantic relationships? To answer these questions, we investigated the association between automatic partner attitudes and judgments of relationship satisfaction in 7 studies. Study 1 was a meta-analysis of 86 correlations that revealed a very weak association between implicitly and explicitly assessed relationship evaluations, and Studies 2a–2c revealed that people failed to accurately report their automatic partner attitudes even when specifically asked to do so. Consistent with the idea that such inaccuracy emerged in part because motivational factors led people to override their automatic attitudes, Studies 3 and 4 demonstrated that automatic partner attitudes better aligned with relationship judgments when people were incentivized with money (Study 3) and had dissolved their relationship (Study 4). Nevertheless, consistent with the idea that overriding automatic attitudes requires the opportunity to deliberate, Studies 4 and 5 demonstrated that automatic partner attitudes better aligned with relationship judgments when people experienced more stress at the daily level (Study 4) and yearly for two years (Study 5). In Study 5, the interaction between stress and automatic attitudes emerged controlling indicators of negativity and was further moderated by relationship enhancing motivations among wives. These studies (a) help explain why automatic partner attitudes predict self-reported relationship satisfaction over time and (b) provide support for theories of social cognition suggesting that people have access to implicitly assessed attitudes that is obscured by motivations and opportunities to deliberate.

People with adverse childhood conditions had faster life history strategies and higher Dark Triad traits, and were more prone to be inflamed (i.e., sexually transmitted infections)

Childhood adversity is associated with adulthood white blood cell count through narcissism. Yaoguo Geng  et al. Personality and Individual Differences, Volume 174, May 2021, 110662. https://doi.org/10.1016/j.paid.2021.110662

h/t David Schmitt Childhood adversity is associated with adulthood white blood cell count through narcissism 

Abstract: The immune system's response to threat is to amass protective white blood cells. We investigated (N = 234) individual differences in white blood cell (WBC) through the lens of life history theory by examining individual differences in (self-reported) childhood threats (i.e., unpredictability and harshness), life history speed, and the Dark Triad traits (i.e., Machiavellianism, narcissism, and psychopathy). People with adverse childhood conditions had faster life history strategies and higher Dark Triad traits, and were more prone to be inflamed (i.e., sexually transmitted infections). In addition, men reported more childhood harshness, Machiavellianism, psychopathy, and a faster life history strategy and a higher WBC count than women did. Moreover, we revealed, through structural equation models, that the effects of childhood adversity on adult WBC count were mediated by narcissism especially in women. Results are discussed in terms of the mechanism underlying the association between childhood environments and physiological health.

Keywords: Childhood harshnessChildhood unpredictabilityLife history strategyDark TriadWhite blood cell count

No differences in subjective well-being & limited differences in personality traits between childfree individuals & parents, not-yet-parents, or childless individuals; politically, childfree individuals were more liberal than parents

Neal, Jennifer W., and Zachary Neal. 2021. “Who Are the Childfree?.” PsyArXiv. February 9. doi:10.31234/osf.io/57bjr

Abstract

Objective: This study examines how childfree individuals differ from parents and other types of non-parents in subjective well-being, political ideology, and personality, and examines whether childfree individuals are a stigmatized outgroup.

Background: Childfree individuals choose not to have children. Most research on parental status and psychosocial characteristics has not distinguished childfree individuals from other non-parents or has relied on non-representative samples.

Method: This study uses a representative sample of 981 Michigan adults to estimate the prevalence of childfree individuals. The study also estimates a series of multiple regressions to examine differences between childfree individuals, parents, and other types of non-parents and to examine whether childfree individuals are perceived by others as an outgroup.

Results: Over a quarter of Michigan adults identified as childfree. After controlling for demographic characteristics, we found no differences in subjective well-being and limited differences in personality traits between childfree individuals and parents, not-yet-parents, or childless individuals. However, childfree individuals were more liberal than parents. Additionally, individuals who have or want(ed) children felt substantially less warm toward childfree individuals than childfree individuals felt toward each other.

Conclusions: Given the prevalence of childfree individuals, the risks of their outgroup status, and their potential role in politics as a uniquely liberal group, it is important for demographic research to distinguish the childfree from others and to better understand these individuals.

Self-Reported Symptoms of COVID-19, Including Symptoms Most Predictive of SARS-CoV-2 Infection, Are Heritable In Some Degree

Self-Reported Symptoms of COVID-19, Including Symptoms Most Predictive of SARS-CoV-2 Infection, Are Heritable. Frances M. K. Williams. Twin Research and Human Genetics, February 9 2021. https://www.cambridge.org/core/journals/twin-research-and-human-genetics/article/abs/selfreported-symptoms-of-covid19-including-symptoms-most-predictive-of-sarscov2-infection-are-heritable/316C6D3F18A25A99B11572BA777606CC

Abstract: Susceptibility to infection such as SARS-CoV-2 may be influenced by host genotype. TwinsUK volunteers (n = 3261) completing the C-19 COVID-19 symptom tracker app allowed classical twin studies of COVID-19 symptoms, including predicted COVID-19, a symptom-based algorithm to predict true infection, derived from app users tested for SARS-CoV-2. We found heritability of 49% (32−64%) for delirium; 34% (20−47%) for diarrhea; 31% (8−52%) for fatigue; 19% (0−38%) for anosmia; 46% (31−60%) for skipped meals and 31% (11−48%) for predicted COVID-19. Heritability estimates were not affected by cohabiting or by social deprivation. The results suggest the importance of host genetics in the risk of clinical manifestations of COVID-19 and provide grounds for planning genome-wide association studies to establish specific genes involved in viral infectivity and the host immune response.

Keywords: SARS-CoV-2 COVID-19 heritability twins anosmia

Superintelligence Cannot be Contained: Lessons from Computability Theory

Superintelligence Cannot be Contained: Lessons from Computability Theory. Manuel Alfonseca et al. Journal of Artificial Intelligence Research, vol 70, Jan 5, 2021. https://doi.org/10.1613/jair.1.12202

Abstract: Superintelligence is a hypothetical agent that possesses intelligence far surpassing that of the brightest and most gifted human minds. In light of recent advances in machine intelligence, a number of scientists, philosophers and technologists have revived the discussion about the potentially catastrophic risks entailed by such an entity. In this article, we trace the origins and development of the neo-fear of superintelligence, and some of the major proposals for its containment. We argue that total containment is, in principle, impossible, due to fundamental limits inherent to computing itself. Assuming that a superintelligence will contain a program that includes all the programs that can be executed by a universal Turing machine on input potentially as complex as the state of the world, strict containment requires simulations of such a program, something theoretically (and practically) impossible.

More terrible than either of these tales is the fable of the monkey’s paw (Jacobs, 1902), written by W. W. Jacobs, an English writer of the beginning of the [20th] century. A retired English working-man is sitting at his table with his wife and a friend, a returned British sergeant-major from India. The sergeant-major shows his hosts an amulet in the form of a dried, wizened monkey’s paw... [which has] the power of granting three wishes to each of three people... The last [wish of the first owner] was for death... His friend... wishes to test its powers. His first [wish] is for 200 pounds. Shortly thereafter there is a knock at the door, and an official of the company by which his son is employed enters the room. The father learns that his son has been killed in the machinery, but that the company... wishes to pay the father the sum of 200 pounds... The grief-stricken father makes his second wish -that his son may return- and when there is another knock at the door... something appears... the ghost of the son. The final wish is that the ghost should go away. In these stories, the point is that the agencies of magic are literal-minded... The new agencies of the learning machine are also literal-minded. If we program a machine... and ask for victory and do not know what we mean by it, we shall find the ghost knocking at our door.

Moreover, they believe that propaganda reduces other citizens’ willingness to protest, which in turn reduces their own willingness to protest; propaganda's power may lie more in the social perceptions & uncertainty it creates

Propaganda, Presumed Influence, and Collective Protest. Haifeng Huang & Nicholas Cruz. Political Behavior, Feb 8 2021. https://rd.springer.com/article/10.1007/s11109-021-09683-0

Abstract: Political propaganda can reduce citizens’ inclinations to protest by directly influencing their preferences or beliefs about the government. However, given that protest is risky in authoritarian societies and requires collective participation, propaganda can also reduce citizens’ inclination to protest by making them think that other citizens, rather than themselves, may have been influenced by propaganda and are, as a result, unwilling to protest. We test this indirect mechanism of propaganda using a survey experiment with Chinese internet users from diverse backgrounds and find that they do believe propaganda affects other citizens’ support for and beliefs about the government more than their own support and beliefs. Moreover, they believe that propaganda reduces other citizens’ willingness to protest, which in turn reduces their own willingness to protest. Therefore, the power of propaganda may sometimes lie more in the social perceptions and uncertainty it creates than in its direct individual effects.

Discussion and Conclusion

This study experimentally shows that people often believe that propaganda increases other people’s support for a regime or their beliefs about a regime’s capacity to maintain stability. In fact, the presumed influence of propaganda on other people’s support for and beliefs about a regime are usually stronger than propaganda’s actual influence on oneself. Consequently, propaganda can reduce people’s perceptions of other people’s willingness to protest, which in turn dilutes their own propensity to protest due to its risky nature under authoritarian regimes. Thus, propaganda can stave off dissent not by directly changing individuals’ own attitudes and intentions but, instead indirectly, by altering people’s perceptions of other people’s attitudes and behavioral intentions.

These findings imply that, due to the complementarity of participation in mass protest, authoritarian regimes have a special advantage by being the agenda setters in the propaganda game. Propaganda does not have to directly change individuals’ own willingness to protest to be effective. As long as propaganda reduces individuals’ perceptions of other people’s willingness to protest, or just makes them uncertain if other citizens have been influenced by it, they will be more timid in challenging the regime. Propaganda can achieve much of its function for the regime simply by sowing uncertainty among citizens about what they think others think and will do. Different from what conventional wisdom often assumes, the power of propaganda may sometimes lie more in the social perception and uncertainty it creates than in changes it induces in individuals’ own political attitudes and beliefs.

The study thus enriches theories of authoritarian propaganda, which have so far focused on propaganda’s direct effect on individuals’ themselves. The results also contrast with findings in the existing literature that in democratic and semi-democratic societies, where basic rights of expression and association are guaranteed, stronger perception of other people’s willingness to participate in protest or voting, or perceptions of protest news’s effects on other people, are associated with a lower willingness to participate (Banning 2006; Cantoni et al. 2019; Lo et al. 2017). In these societies, participation is more of a public good that demands a threshold level of contribution: Perception of other people’s participation reduces the need for oneself to participate in order to meet the threshold and, thus, could drive down one’s own willingness to participate. In other words, these are games of substitutes. Collective protests in authoritarian settings, however, are strategic games of complements (Chwe 2003; Edmond 2013; Gehlbach et al. 2016): The more/less willing other people are to participate, the more/less willing are individuals themselves. It is in this strategic setting that propaganda can inhibit people’s willingness to protest by reducing their perceptions of other people’s willingness to protest. And it is this mechanism that contributes to preference falsification, pluralistic ignorance, and the breakdown of common knowledge (Chwe 2003; Havel 1985; Kuran 1991).

Besides enriching our understanding of authoritarian propaganda, this study also contributes to the literature on the influence of presumed media influence. The standard literature on the influence of presumed influence focuses on people’s perceptions of media’s influence on others, without comparing the influence on others with influence on oneself. The third-person effect literature, on the other hand, focus on the discrepancy between media’s presumed influence on oneself and on others, without considering wither the presumed effect on oneself is accurate, or whether the presumed influence of media is really stronger than its actual influence on oneself. We show that propaganda’s presumed effects on others can be stronger than its actual effects on oneself, not just stronger than its presumed effects on oneself. It is this “real” presumed influence of propaganda that leads to one’s perceptions of propaganda’s influence on other people’s behavior, which in turn affects one’s own behavior.

One limitation of the study is that the propaganda messages had negative effects on the respondents’ perceptions of other people’s protest willingness, hence negative indirect effects on their own protest willingness, but the messages had either null or positive direct effects on the respondents’ protest willingness. As discussed above, the positive direct effect is likely because the propaganda messages about the greatness of China and its leader encouraged the respondents to express willingness to dissent against injustice and government malfeasance, which were holding China back. Self-other perceptual discrepancies have always been recognized in the third-person effect literature as a kind of inconsistency or bias. Our study suggests the self-other discrepancies may be larger than typically understood: A media message’s self and other effects may differ not just in magnitude but also in direction. Understanding the causes and/or prevalence of the directional divergence goes beyond the scope of this study, but it is potentially an important issue for future research.

A general theory about how sexual desires develop is provided that may explain how something, including another person, becomes an object of sexual desire

High and Tight, Please: Self-explanations for Experiencing Short Haircuts as Erotic. Robert W. Mitchell. Sexuality & Culture, Feb 9 2021. https://rd.springer.com/article/10.1007/s12119-021-09815-y

Abstract: Sexologists have infrequently asked individuals to describe what led them to their sexual desires. In this study, 264 men and 7 women answered a questionnaire about their sexual interest in short haircuts on men, part of which asked them about any events or ideas they had that might explain their sexual desires. Surprisingly, a substantial minority of the men desired women as sexual partners. Almost 80% of the participants provided responses, which were examined for themes related to what might have caused their sexual interest in short haircuts on men, resulting in 16 themes, most of which help explain why short haircuts became objects of interest and fascination. The 10 most common themes are presented in detail, and a general theory about how sexual desires develop is provided that may explain how something, including another person, becomes an object of sexual desire.

Sharing food can reduce the perceived fattening potential of a consumption episode without biasing caloric estimates, even when explicit caloric information is provided

Your Fries are Less Fattening than Mine: How Food Sharing Biases Fattening Judgments Without Biasing Caloric Estimates. Nükhet Taylor  Theodore J. Noseworthy. Journal of Consumer Psychology, December 17 2020. https://doi.org/10.1002/jcpy.1214

Abstract: Food sharing has become quite popular over the last decade, with companies offering food options specifically designed to be shared. As the popularity has grown, so too has concerns over the potential negative impact on consumer health. Despite companies’ explicit claims to the contrary, critics maintain that food sharing may be encouraging excessive caloric intake. The current article provides the first systematic exploration of why this may be happening. Three main and two supplementary studies suggest that food sharing reduces perceived ownership, which, in turn, leads people to mentally decouple calories from their consequence. Thus, sharing can reduce the perceived fattening potential of a consumption episode without biasing caloric estimates. This phenomenon persists even when explicit caloric information is provided, and it applies to both healthy and unhealthy foods. Importantly, we establish a relevant downstream consequence by illustrating that people tend to subsequently select calorie‐dense foods after underestimating the fattening potential of a shared consumption episode. A roadmap for future research and practical implications are discussed.

General Discussion

The current work investigated how food sharing impacts health‐related judgments. Our findings revealed that sharing is not biasing caloric estimates but is biasing how consumers construe the consequence of their caloric intake. Specifically, food appears less fattening when it is shared (study 1). We replicated these findings with both healthy and unhealthy food and with explicit calorie information (study 2). Thus, rather than a motivational mechanism that hinges on unhealthy food, sharing is causing a general decoupling of calories and their consequence. Importantly, reduced fattening judgments also reduced the possibility that consumers will correct for the extra caloric intake in subsequent choice (study 3). All studies confirmed that reduced perceived ownership underscored these results. Thus, elevating perceived ownership elevated fattening judgments (study 3). Two supplementary studies supported these conclusions (MDA: Appendix S1 pp. 14–20). Finally, a Bayesian SPM provided strong evidence in favor of sharing impacting fattening judgments and not caloric estimates.

This work represents a cautionary note for public policymakers and for companies promoting food sharing. When introducing share‐size snacks, Mars‐Wrigley claimed that food sharing may help weight maintenance by facilitating portion control (Mars, 2017). Our findings suggest that food sharing may be encouraging excessive caloric intake by leading consumers to underestimate the fattening potential brought on by shared food consumption.

Exploration and Future Research

In the spirit of a research report, we explored other ways in which sharing may impact perceptions. Specifically, while caloric estimates were not impacted, related factors such as perceived size and/or healthiness may have been impacted. However, we were not able to support these possibilities (MDA: Appendix S1 pp. 4–7). We also considered that people may feel less responsible over their consumption when sharing food. We did not find this to be the case either (MDA: Appendix S1 p. 4). Nevertheless, researchers can build on these attempts. For instance, although sharing did not bias the perceived healthiness of stereotypically healthy/unhealthy foods, it could bias perceptions of a health‐ambiguous food (e.g., pasta salad). Similarly, although sharing did not alter size perceptions, it may be that sharing elevates the desire for larger food options (Taylor, Noseworthy, & Pancer, 2019).

Future work can pinpoint why lower perceived ownership makes caloric intake seem inconsequential. One possibility relates to mental accounting. Extant work has shown that consumers use mental accounts to keep track of both monetary expenses (Thaler, 1985) and daily caloric budgets (Khare & Innman, 2009). Thus, it may be that consumers do not include calories from shared consumption in their caloric budget because they believe these calories do not belong to them. A related principle in categorization theory that fits the mental accounting lens could be how psychological budgets interact. If consumers see calorie budgets similar to financial budgets, sharing in one may lead people to compensate for a biased shortfall in the other—re: fluid compensation (Taylor & Noseworthy, 2020). Another possibility relates to egocentric categorization theory (Weiss & Johar, 2016), which shows that people assimilate to products they own, and contrast products they do not own. This may explain why people decouple calories from their consequences to the self. A final possibility is how people mentally construe (un)owned objects. People perceive things to be of lesser consequence when they are psychologically distant (Polman et al., 2018). A similar mindset mechanism could be contributing to our findings.

Future work can investigate the implications of our findings for other collaborative consumption domains. One area is household consumption, whereby typically one person purchases the food consumed by others (Belk, 2010).

Future work may also explore how external cues influence the tendency to share food. One intriguing question is how sharing is impacted when consumers are faced with cues of contagious disease, such as during flu season or during a health pandemic (e.g., Covid‐19). Extant work suggests two plausible accounts. The first one is that contagious disease cues elicit disgust and a desire to self isolate (Galoni & Noseworthy, 2015; Lerner & Keltner, 2000), which may dampen food sharing in general. The second one is that disease cues reduce the desire to interact with the unfamiliar, but elevate the desire to interact with the familiar (Galoni, Carpenter, & Rao, 2020). The end result may be a lower tendency to share with distant others such as acquaintances and colleagues, but greater tendency to share with close others such as family members and significant others. Future work may expand on these possibilities.

Finally, a major limitation of the current work is that the consequences of food sharing were examined via vignettes. We strongly encourage future research to examine actual consumption in a real‐world setting. This would not only establish the ecological validity of the current findings but would also provide a richer understanding of the social dynamics behind food sharing. Certainly, more work is needed in this area.

Self-perceived smile attractiveness: The increased strength of the effect in females provides support to the notion that females are overall more aware of their smile and the impact it has on their public image

Smile dimensions affect self-perceived smile attractiveness. Simone Horn, Natalia Matuszewska, Nikolaos Gkantidis, Carlalberta Verna & Georgios Kanavakis. Scientific Reports volume 11, Article number: 2779. Feb 2 2021. https://www.nature.com/articles/s41598-021-82478-9

Rolf Degen's take: (17) Rolf Degen on Twitter: ""Females are overall more aware of their smile and the impact it has on their public image." https://t.co/enAWpkRG5S https://t.co/tAWOBdc5VQ" / Twitter

Abstract: Facial expressions play a leading role in human interactions because they provide signaling information of emotion and create social perceptions of an individuals’ physical and personality traits. Smiling increases socially perceived attractiveness and is considered a signal of trustworthiness and intelligence. Despite the ample information regarding the social importance of an attractive smile, little is known about the association between smile characteristics and self-assessed smile attractiveness. Here we investigate the effect of smile dimensions on ratings of self-perceived smile attractiveness, in a group of 613 young adults using 3D facial imaging. We show a significant effect of proportional smile width (ratio of smile width to facial width) on self-perceived smile attractiveness. In fact, for every 10% increase in proportional smile width, self-perceived attractiveness ratings increased by 10.26%. In the present sample, this association was primarily evident in females. Our results indicate that objective characteristics of the smile influence self-perception of smile attractiveness. The increased strength of the effect in females provides support to the notion that females are overall more aware of their smile and the impact it has on their public image.

Discussion

The purpose of this study was to explore the effect of smile dimensions on self-assessment of smile attractiveness in a large young adult population, using three-dimensional data. To our knowledge this is the first assessment of the association of self-perceived smile attractiveness to smile dimensions. The findings demonstrated that self-perceived smile attractiveness was affected by smile dimensions, with proportionally wider smiles perceived as more attractive. This effect was primarily evident in females.

As the societal esthetic demands influence interpersonal relationships heavily, medical and dental disciplines studying the human face continue to shift their focus on treatment trajectories that optimize facial and smile esthetics. Following an intervention in the face, self-perceived esthetic outcomes comprise important components of patient satisfaction with treatment28,29. Smiling can trigger a variety of emotions and biases during human interactions8,10,11 and it may be the most important factor controlling judgments of overall facial attractiveness30. Thus, the identification of factors that affect self-perceived smile attractiveness is important to set treatment goals that meet patients’ needs and demands, when treatment is expected to affect smile.

We were able to identify only one previous study associating smile characteristics to self-perceived smile attractiveness12. This was conducted on a sample of white adult men, who were asked to evaluate their smiles according to tooth size and color, tooth visibility, and upper lip position, while viewing their smiling image. The results indicated that tooth size and color appeared to have a larger effect on attractiveness ratings, however, smile dimensions were not evaluated and therefore no direct comparisons to our results are possible.

Considering external ratings, in growing individuals, a thicker upper lip was shown to influence observers’ judgements of an attractive smile31; while another study on young adult females reported that only smile height was related to smile attractiveness18. On the other hand, Schabel et al.32 were not able to identify any dimensional smile characteristic with a direct effect on smile attractiveness. Apart from the external ratings, the above studies had samples much smaller to ours (48–60 subjects), tested 2D images, and had different designs. Thus, no direct comparison to our study findings can be made.

No previous study has assessed smile dimensions in relation to face dimensions (proportional smile dimensions). During social interactions, attention is primarily shifted between the mouth and the eyes33; and thus, in real life, dimensional characteristics of facial structures are mostly viewed in relation to others. Therefore, it is safe to assume that quantitative assessments, which take the variability in facial size and shape into consideration are more likely to provide realistic information about smile dimensions. Here, we show that smile width, as related to facial width, has a significant effect on self-perceived smile attractiveness; participants with proportionally wider smiles, found their smiles more attractive. No such effect was evident for the original smile width.

Our sample population exhibited significant sexual dimorphism in smile dimensions, with males presenting wider smiles and faces than females. This is in agreement with previous studies that have explored smile dimensions using three-dimensional data34,35,36,37. However, it can be attributed to males exhibiting overall larger facial dimensions, since in our sample females had higher proportional smile widths. Our findings also allow for speculation that young adult women are more influenced by their objective smile appearance when evaluating their own smile attractiveness. Although smiling kindles an equally favorable response in females and males during social encounters6, females are consistently found to smile more38. This might be an inherent sexual characteristic of females or they may pay more attention or even be more aware of the positive responses generated during smile, and thus, exert a more conscious effort to smile. The latter might be supported by our finding that in contrast to young adult females, in males, smile dimensions had an undetectable effect on self-perceived smile attractiveness. There are numerous social and cultural causes for women being more conscious of their objective smile characteristics, since they are often expected to be friendlier and more emotionally expressive than men39,40,41. In addition, smiling frequency and intensity has been associated to hormonal changes during physical development; high testosterone levels, for example, have an inhibitory role in social smiling42,43. As a result, males may either have an intrinsic hesitation to smile or may very well not consider it an important feature of their social image. This could potentially lead them to rate their smile less favorably compared to females, which was clearly evident from our results and, thus, also supports the above thought process.

Special considerations and limitations

The results of this investigation should be assessed within the context of the applied methodology. Our study population was limited to a group of highly educated young adults, in order to control for the potential confounding effect of educational status44,45 and age46. The findings may thus not represent the general population.

In addition, participants were not allowed to look at their own pictures prior to evaluating their attractiveness. Being exposed to one’s own photograph tends to alter self-perception of appearance47, therefore this could have led to different results. However, it was preferred to obtain a more “genuine” response in order to avoid the effect of the instantaneous stimulus generated from the exposure to their facial images. In addition, some participants may have been influenced when smiling by the presence of a person in the research area to whom they wanted to appear attractive. Although this could potentially affect our results, it is unlikely given the large sample size and the minimal measurement error found.

The present study focused solely on smile dimensions. However, there are various other smile components that might affect smile attractiveness, but they were not considered in our study. Such factors could have been expected to confound ratings and affect the study outcomes, but we think that the large sample size adequately addresses this issue.

Anatomical landmark variability could also be a possible source of error in this study since the labial commissures of the mouth tend to not displace consistently upon smiling, between different image acquisitions of the same individual48. However, this confounder is not expected to have influenced our results due to the large sample population and the high standardization of image acquisition.

Moderate, naturally occurring ethanol concentration of 4% results in increased Drosophila larval fitness; but higher concentrations of 10% & 20% ethanol, which rarely or never appear in nature, increase mortality

Ethanol-guided behavior in Drosophila larvae. Isabell Schumann et al. bioRxiv, Feb 8 2021. https://doi.org/10.1101/2021.02.07.430116

Rolf Degen's take: The larvae of fruit flies are not only strongly attracted to alcohol, it also gives them a greater life expectancy

Abstract: Chemosensory signals allow vertebrates and invertebrates not only to orient in its environment toward energy-rich food sources to maintain nutrition but also to avoid unpleasant or even poisonous substrates. Ethanol is a substance found in the natural environment of Drosophila melanogaster. Accordingly, D. melanogaster has evolved specific sensory systems, physiological adaptations, and associated behaviors at its larval and adult stage to perceive and process ethanol. To systematically analyze how D. melanogaster larvae respond to naturally occurring ethanol, we examined ethanol-induced behavior in great detail by parametrically reevaluating existing approaches and comparing them with new experiments. Using behavioral assays, we confirm that larvae are attracted to different concentrations of ethanol in their environment. This behavior is controlled both by olfactory and contact cues. It is independent of previous exposure to ethanol in their food. Moreover, moderate, naturally occurring ethanol concentration of 4% results in increased larval fitness. On the contrary, higher concentrations of 10% and 20% ethanol, which rarely or never appear in nature, increase larval mortality. Finally, ethanol also serves as a positive teaching signal in learning and memory and updates valence associated with simultaneously processed odor information. Since information on how larvae perceive and process ethanol at the genetic and neuronal level is limited, the establishment of standardized assays described here is an important step towards their discovery.