Friday, April 19, 2019

Advantageous Selection in a Voluntary Army: Volunteers and drafted men showed no significant difference in fatalities, but volunteers earned distinguished awards at a higher rate than drafted men

“Gallantry in Action”: Evidence of Advantageous Selection in a Voluntary Army. Javier A. Birchenall, Thomas G. Koch. The Journal of Law and Economics, Volume 58, Number 1, February 1, 2015.

Abstract: A voluntary army’s quality exceeds or falls below a drafted army’s average quality depending on whether selection is advantageous or adverse. Using a collection of data sets that cover the majority of the US Army soldiers during World War II, we test for adverse selection into the army. Rather, we find advantageous selection: volunteers and drafted men showed no significant difference in fatalities, but volunteers earned distinguished awards at a higher rate than drafted men, particularly after the attack on Pearl Harbor. Analyses at the level of units concur with our findings based on enlistment records.

Savoring, or one’s tendency to attend to and enjoy previous, current, and future positive events, is positively related to relationship satisfaction; especially so in the anticipative branch of savoring

Lenger, K. A., & Gordon, C. L. (2019). To have and to savor: Examining the associations between savoring and relationship satisfaction. Couple and Family Psychology: Research and Practice, 8(1), 1-9.

Abstract: Savoring, or one’s tendency to attend to and enjoy previous, current, and future positive events, is composed of 3 facets: savoring in anticipation, savoring the present moment, and savoring in reminiscence. Whereas research is now accumulating on potential benefits that savoring may have for a variety of individual indicators of well-being, it remains unclear whether savoring may also be relevant to relational well-being. The present investigation seeks to address this gap in the literature by establishing whether savoring is associated with relationship satisfaction, and if so, which facet(s) of savoring are the strongest predictors of relationship satisfaction. Data were collected from 122 undergraduates from a southeastern university currently participating in monogamous dating relationships. Analyses revealed that total savoring as well as each facet of savoring, namely, anticipation, present moment, and reminiscence, were positively related to relationship satisfaction. A subsequent simultaneous multiple regression analysis indicated that anticipation uniquely predicted relationship satisfaction, above and beyond reminiscence and present moment facets of savoring. Overall, it appears that attending to and enjoying positive events is associated with a happier relationship. Furthermore, these data suggest that anticipation may be a component of savoring that is particularly relevant to relationship satisfaction. Results are discussed in the context of optimizing relational well-being.

Visual perfection: Our data are best explained by a model that is based on the optimal decision strategy, but with imperfections in its execution (suboptimal inference)

Imperfect Bayesian inference in visual perception. Elina Stengård, Ronald van den Berg. PLOS, April 18, 2019.

Abstract: Optimal Bayesian models have been highly successful in describing human performance on perceptual decision-making tasks, such as cue combination and visual search. However, recent studies have argued that these models are often overly flexible and therefore lack explanatory power. Moreover, there are indications that neural computation is inherently imprecise, which makes it implausible that humans would perform optimally on any non-trivial task. Here, we reconsider human performance on a visual-search task by using an approach that constrains model flexibility and tests for computational imperfections. Subjects performed a target detection task in which targets and distractors were tilted ellipses with orientations drawn from Gaussian distributions with different means. We varied the amount of overlap between these distributions to create multiple levels of external uncertainty. We also varied the level of sensory noise, by testing subjects under both short and unlimited display times. On average, empirical performance—measured as d’—fell 18.1% short of optimal performance. We found no evidence that the magnitude of this suboptimality was affected by the level of internal or external uncertainty. The data were well accounted for by a Bayesian model with imperfections in its computations. This “imperfect Bayesian” model convincingly outperformed the “flawless Bayesian” model as well as all ten heuristic models that we tested. These results suggest that perception is founded on Bayesian principles, but with suboptimalities in the implementation of these principles. The view of perception as imperfect Bayesian inference can provide a middle ground between traditional Bayesian and anti-Bayesian views.

Author summary: The main task of perceptual systems is to make truthful inferences about the environment. The sensory input to these systems is often astonishingly imprecise, which makes human perception prone to error. Nevertheless, numerous studies have reported that humans often perform as accurately as is possible given these sensory imprecisions. This suggests that the brain makes optimal use of the sensory input and computes without error. The validity of this claim has recently been questioned for two reasons. First, it has been argued that a lot of the evidence for optimality comes from studies that used overly flexible models. Second, optimality in human perception is implausible due to limitations inherent to neural systems. In this study, we reconsider optimality in a standard visual perception task by devising a research method that addresses both concerns. In contrast to previous studies, we find clear indications of suboptimalities. Our data are best explained by a model that is based on the optimal decision strategy, but with imperfections in its execution.

Popular summary:

Sexual selection & the evolution of male & female cognition in seed beetles: polygamous males outperform cognitively monogamous males; polygamous females show no improvement

Sexual selection and the evolution of male and female cognition: a test using experimental evolution in seed beetles. Julian Baur, Jean d'Amour, David Berger. bioRxiv 514711, Jan 9 2019.

Abstract: The mating mind hypothesis, originally aimed at explaining human cognition, holds that the socio-sexual environment shapes cognitive abilities among animals. Similarly, general sexual selection theory predicts that mate competition should benefit individuals carrying "good genes" with beneficial pleiotropic effects on general cognitive ability. However, few experimental studies have evaluated these related hypotheses due to difficulties of performing direct tests in most taxa. Here we harnessed the empirical potential of the seed beetle study system to investigate the role of sexual selection and mating system in the evolution of cognition. We evolved replicate lines of beetle under enforced monogamy (eliminating sexual selection) or polygamy for 35 generations and then challenged them to locate and discriminate among mating partners (male assays) or host seeds (female assays). To assess learning, the same beetles performed the task in three consecutive rounds. All lines learned the task, improving both within and between trails. Moreover, polygamous males outperformed monogamous males. However, there were no differences in the rate of learning between males of the two regimes, and polygamous females showed no improvement in host search, and even signs of reduced learning. Hence, while sexual selection was a potent factor that increased cognitive performance in mate search, it did not lead to the general increase in cognitive abilities expected under the mating mind hypothesis or general good genes theory. Our results highlight sexually antagonistic (balancing) selection as a potential force maintaining genetic variation in cognitive traits.

From 2018: High consumption of pornography correlates with the more frequent practice of some sexual behaviors; there is a relationship between the intensity of certain sexual behaviors & affective temperament

Sexo, pornografia e temperamento. Laura Dick e Silva. Dissertation, Pontifícia Universidade Católica do Rio Grande do Sul, Escola de Medicina, Aug 2018,

Introduction: A satisfactory and healthy sex life is one of four markers considered by the World Health Organization to measure quality of life. When we study sexual behaviors, we can create evidence that can be used in different ways in the health area.

Objectives: To analyze the relationship between the consumption of pornography and certain sexual practices, as well as the relationship between affective temperament and sexual behaviors. Methods: Participants between the ages of 21 and 50 were included, who answered standardized questions about the consumption of pornography and certain sexual practices (e.g. frequency of sexual intercourse, frequency of masturbation, number of sexual partners, casual sex), through the website Through this validated questionnaire it was possible to categorize individuals by their affective temperaments. Statistical analyzes were performed using chi-square, Spearman’s correlation and multinomial logistic regression.

Results: The high consumption of pornography correlates with the more frequent practice of some sexual behaviors, which is different between men and women. In addition, there is a relationship between the intensity of the practice of certain sexual behaviors and the affective temperament of individuals. Individuals with externalizing temperaments are more strongly involved in the practice of sexual behaviors, whereas the opposite is observed among internalized individuals.

Conclusion: The consumption of pornography is associated with the practice and frequency of sexual behaviors and there are differences between men and women in relation to sexual behaviors and attitudes. The intensity of sexual behaviors is related to the type of affective temperament.

Sex-positive personal characteristics (attractiveness, sexual fantasy, pornography use) & positive relational ones (commitment, egalitarianism, & sexual frequency) are related to more sexual novelty

Encouraging erotic variety: Identifying correlates of, and strategies for promoting, sexual novelty in romantic relationships. Marissa N. Rosa et al. Personality and Individual Differences, Volume 146, 1 August 2019, Pages 158-169.

Abstract: In the present investigation, we identified correlates of sexual novelty in existing relationships and also investigated whether experimentally manipulating persuasive information about sexual novelty could encourage sexual novelty within a relationship. Participants in committed relationships of 6 months or longer were recruited online through Amazon's Mechanical Turk to complete a two-part survey on sexual relationships. The initial survey (Time 1) was completed by 352 predominantly White US citizens (204 women, 146 men, 2 unreported), and a subset of 244 people (140 women, 101 men, 3 unreported) completed the follow-up survey two weeks later (Time 2). We found that several sex-positive personal characteristics (e.g., pornography use and sexual fantasy) and positive relational characteristics (e.g., commitment, egalitarianism, and sexual frequency) are related to engaging in sexual novelty, as well as desire for sexual novelty, willingness to initiate sexual novelty, and willingness to comply with partner-initiated sexual novelty. We also found that certain persuasive strategies (i.e., those incorporating fear appeals, narrative accounts, or examples of successful initiation strategies) may be effective at altering perceptions of sexual novelty and increasing novel intimate behavior between relationship partners.

General discussion

In order to extend the literature on sexual novelty, the current study sought to identify correlates of sexual novelty and to investigate whether learning more about sexual novelty could result in changes in attitudes and behaviors toward sexual novelty within a relationship. Whereas previous research has shown that engaging in arousing, novel behaviors can increase sexual satisfaction and relationship satisfaction (Aron et al., 2000; Morton & Gorzalka, 2015), our correlational results identified both personal factors (i.e., age, religiosity, bodily attractiveness, body consciousness, sexual boredom, sexual fantasy, and pornography use) and relational factors (i.e., length of relationship, length of sexual relationship, commitment, egalitarianism, and sex frequency) associated with how much sexual novelty a person is likelyto engage in. Additionally, prior research has documented how detrimental sexual boredom can be to a relationship, potentially resulting in infidelity (e.g.,Allen et al., 2008), divorce (e.g., Counts & Reid, 1987),or relationship dissolution (e.g.,Hill et al., 1976). Therefore, an important contribution of our study is thefinding that levels of sexual novelty can be influenced—and levels of sexual boredom can potentially be decreased as a result—through the introduction of additionalinformation about sexual novelty using certain persuasive methods, further extending the literature on the use of fear appeals (e.g., Tannenbaum et al., 2015), narrative accounts (e.g., De Wit et al., 2008), strategies (e.g., Humphreys & Newby, 2007), and self-efficacy (e.g.,Azjen, 1991) in persuasion.

Another interesting result from the current study was the positiverelationship we found between sexual novelty and religiosity. Contrary to our predictions, the more religious people were, the more likely they were to report engaging in sexual novelty in their current relationships. However, Matthews et al. (2018) found both a positive and a negative relationship between religiosity and sexual novelty in two different samples; as such, it is possible that the conflicting finding of the current research may be an anomaly, and further replication is necessary to fully understand the relationship between religiosity and sexual novelty. One possible explanation is that more religious people may notactually be engaging in more sexual novelty but rather subjectively interpreting their sexual activities as more novel. Consistent with this notion, research shows a negative association between conventional religiosity and sensation seeking (Zuckerman & Neeb, 1980); thus, thethreshold for novel sexual activity may be lower for more religious people.

We also found an interesting correlation between sexual boredomand sexual novelty. As expected, the more sexual boredom people re-ported experiencing, the more likely they were to report lower levels ofsexual novelty within their current relationships and the less willingthey were to initiate and comply with sexual novelty initiated by apartner. However, people who reported experiencing more sexualboredom were also more likely to desire sexual novelty within theirrelationships. The idea that people who are bored sexually have a desire for sexual novelty but are unwilling or unmotivated to take action to fulfill this desire seems to be related to the view that sexual boredom is unavoidable in long-term relationships (Tunariu & Reavey, 2003). Similarly, given that sexual boredom predicts relationship and sexual dissatisfaction (e.g., Tunariu & Reavey, 2007), it is plausible that thelack of motivation to engage in sexual novelty with their relationshippartner could lead individuals to fulfill their desire for sexual novelty by seeking extra-dyadic relationships.