Sex differences in cooperativeness:An experiment with Buryats in Southern Siberia

We report on an experimental study that was set up to reveal differences in the tendencies of men and women to cooperate in same-sex interactions. Former studies on this subject were mostly conducted in industrialized modern societies. In contrast, we tested the cooperation tendency among Buryats, a people from Southern Siberia of Mongolian origin. All subjects participated in (1) one iterated Public Goods Game in a group of four individuals of the same sex and (2) four one-shot Prisoner's Dilemma games with different partners of the same sex. The interactions were in a face-to-face setting, but any intentional communication during the experiments was prohibited. We found that Buryat men were more cooperative than Buryat women in both types of same-sex interactions. In particular, the fraction of men employing a strategy of unconditional cooperation in the iterated Public Goods Game was much higher (36%) than the fraction of unconditional cooperators among women (21%). In general, the behavior of men was less context dependent than the behavior of women. In both sexes, individuals who were more cooperative in one type of game tended to be more cooperative in the other type of game. Although direct communication was prohibited, the interaction partners in the Prisoner's Dilemma games employed the same strategy much more frequently than expected by chance. We conclude that, even among strangers, the exchange of subtle signals is sufficient to coordinate strategic decisions

Effects of sex and sex-related facial traits on trust and trustworthiness: An experimental study

The ability to trust others, including strangers, is a prerequisite for human cooperation. Economically it is not rational to trust strangers, as trust can be easily exploited. Still, generally, the level of trust toward strangers is relatively high. Trust is closely related to trustworthiness: when trusting others, one expects them to reciprocate. Some individuals elicit more trust than others. Apparently, humans use subtle cues for judging the trustworthiness of their interaction partners. Here, we report on an experiment that investigates trust and trustworthiness in a population of 176 mainly Dutch students. The aims of our study were: (1) to investigate how the sex of interaction partners and their facial appearance (femininity/masculinity) affect the degree of trust and trustworthiness, compared to fully anonymous conditions; (2) to test whether individuals who elicit trust in their interaction partners are trustworthy themselves. Each subject of our experiment played five one-shot Trust Games: one with an anonymous interaction partner, and four “personalized” games after seeing a 20 s silent video of their interaction partner (twice same-sex, and twice opposite-sex). The degree of facial sexual dimorphism was investigated with geometric morphometrics based on full-face photographs. Our results revealed that, despite the already high level of trust in the anonymous setting, the personalization of interactions had a clear effect on behavior. Females elicited more trust in partners of both sexes. Interestingly, females with more feminine faces elicited less trust in both male and female partners, while males with more masculine facial shape were more trusted by females, but less trusted by males. Neither sex nor facial femininity/masculinity predicted trustworthiness. Our results demonstrate that (1) sex and sex-related facial traits of interaction partners have a clear effect on eliciting trust in strangers. However, (2) these cues are not reliable predictors of actual trustworthiness

First results from the Soviet-American gallium experiment

The Soviet-American Gallium Experiment is the first experiment able to measure the dominant flux of low energy p-p solar neutrinos. Four extractions made during January to May 1990 from 30 tons of gallium have been counted and indicate that the flux is consistent with 0 SNU and is less than 72 SNU (68% CL) and less than 138 SNU (95% CL). This is to be compared with the flux of 132 SNU predicted by the Standard Solar Model. © 1991

The Baksan gallium solar neutrino experiment

A radiochemical 71Ga-71Ge experiment to determine the integral flux of neutrinos from the sun has been constructed at the Baksan Neutrino Observatory in the USSR. Measurements have begun with 30 tonnes of gallium. An additional 30 tonnes of gallium are being installed so as to perform the full experiment with a 60-tonne target. The motivation, experiment procedures, and present status of this experiment are described. © 1990

Effects of sex and appearance on trust and trustworthiness

Supplementary Materials for the manuscript: Effects of sex and appearance on trust and trustworthines

Effects of sex and appearance on trust and trustworthiness

The ability to trust other individuals, including strangers, is a prerequisite for human cooperation. Economically it is not rational to trust others, as trust can be easily exploited. Still, generally the level of trust toward strangers is relatively high. Trust is closely related to trustworthiness: when trusting others, one expects them to reciprocate. Some individuals elicit more trust than others. Apparently, humans use subtle cues for judging the trustworthiness of their interaction partners. Here we report on an experiment that investigates trust and trustworthiness in a population of 176 mainly Dutch students. We address the following questions: What is the degree of trust and trustworthiness towards anonymous interaction partners? How do trust and trustworthiness change in a personalised setting (after seeing a silent video of a partner)? How does the sex and the facial features of the interaction partner affect trust and trustworthiness? The subjects in our experiment played a Trust Game that was shaped into a real-life story. The trustor was in the role of a farmer, who had to decide whether to entrust goods to a trustee, who in turn was in the role of a market seller. Trusting others could bring some extra profit to a trustor, but could also lead to loss of everything. The features of facial appearance were investigated with geometric morphometrics based on full-face photographs. Our results revealed that already under anonymous conditions the level of trust and trustworthiness was very high (70% of individuals trusted anonymous strangers). No sex differences between males and females were found in the anonymous setting. Under personalized conditions females elicited more trust than males in partners of the both sexes. Interestingly, females with more feminine facial shape elicited less trust in both male and female partners, while males with more masculine facial shape were more trusted by females, but less trusted by males. Neither gender nor facial femininity predicted actual trustworthiness of participants. Our results demonstrate that sex and appearance of interaction partners have a clear effect on eliciting trust in strangers. However, these cues do not seem to be reliable predictors of actual trustworthiness