Social Rewards Enhance Offline Improvements in Motor Skill

Motor skill memory is first encoded online in a fragile form during practice and then converted into a stable form by offline consolidation, which is the behavioral stage critical for successful learning. Praise, a social reward, is thought to boost motor skill learning by increasing motivation, which leads to increased practice. However, the effect of praise on consolidation is unknown. Here, we tested the hypothesis that praise following motor training directly facilitates skill consolidation. Forty-eight healthy participants were trained on a sequential finger-tapping task. Immediately after training, participants were divided into three groups according to whether they received praise for their own training performance, praise for another participant''s performance, or no praise. Participants who received praise for their own performance showed a significantly higher rate of offline improvement relative to other participants when performing a surprise recall test of the learned sequence. On the other hand, the average performance of the novel sequence and randomly-ordered tapping did not differ between the three experimental groups. These results are the first to indicate that praise-related improvements in motor skill memory are not due to a feedback-incentive mechanism, but instead involve direct effects on the offline consolidation process.     

How Social and Nonsocial Context Affects Stay/Leave Decision-Making: The Influence of Actual and Expected Rewards

This study investigated whether deciding to either stay with or leave a social relationship partner, based on a sequence of collaborative social interactions, is impacted by (1) observed and (2) anticipated gains and losses associated with the collaboration; and, importantly, (3) whether these effects differ between social and nonsocial contexts. In the social context, participants played an iterated collaborative economic game in which they were dependent on the successes and failures of a game partner in order to increase their monetary payoff, and in which they were free to stop collaborating with this partner whenever they chose. In Study 1, we manipulated the actual success rate of partners, and demonstrated that participants decided to stay longer with ''better'' partners. In Study 2, we induced prior expectations about specific partners, while keeping the objective performance of all partners equal, and found that participants decided to stay longer with partners whom they expected to be ''better'' than others, irrespective of actual performance. Importantly, both Study 1 and 2 included a nonsocial control condition that was probabilistically identical to the social conditions. All findings were replicated in nonsocial context, but results demonstrated that the effect of prior beliefs on stay/leave decision-making was much less pronounced in a social than a nonsocial context.     

A Temporal Dimension to the Influence of Pollen Rewards on Bee Behaviour and Fecundity in Aloe tenuior

The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.     

Chemosignals of Stress Influence Social Judgments

Human body odors have important communicative functions regarding genetic identity, immune fitness and general health, but an expanding body of research suggests they can also communicate information about an individual’s emotional state. In the current study, we tested whether axillary odors obtained from women experiencing psychosocial stress could negatively influence personality judgments of warmth and competence made about other women depicted in video scenarios. 44 female donors provided three types of sweat samples: untreated exercise sweat, untreated stress sweat and treated stress sweat. After a ‘washout’ period, a commercial unscented anti-perspirant product was applied to the left axilla only to evaluate whether ‘blocking’ the stress signal would improve the social evaluations. A separate group of male and female evaluators (n = 120) rated the women in the videos while smelling one of the three types of sweat samples. Women in the video scenes were rated as being more stressed by both men and women when smelling the untreated vs. treated stress sweat. For men only, the women in the videos were rated as less confident, trustworthy and competent when smelling both the untreated stress and exercise sweat in contrast to the treated stress sweat. Women’s social judgments were unaffected by sniffing the pads. The results have implications for influencing multiple types of professional and personal social interactions and impression management and extend our understanding of the social communicative function of body odors.     

Influence of Paddock Size on Social Relationships in Domestic Horses

The aim of this study was to explore whether the size of paddocks affected social interactions within a group of horses. Furthermore, the effects of the gender composition in groups on social behavior were investigated. The research was done in a horse-riding center. A total of 78 horses and ponies, forming 3 groups, were included in the study. The time of the observation was divided into 2 periods. The data obtained from the 1st period (the horses were on relatively small paddocks) and the 2nd period (the paddocks were significantly bigger) were compared. The findings uniformly indicated that an enlargement of grass paddocks resulted in a significant decline in the number of social interactions, both agonistic and play types, in all studied herds. A likely principal reason for a change in the number of social interactions seems to be feeding management and how it changed between seasons, rather than paddock size. No effect of group composition on social interaction was found in terms of aggressive interaction, and only 1 group differed regarding friendly interaction.     

Influence of Reciprocal Links in Social Networks

How does reciprocal links affect the function of real social network? Does reciprocal link and non-reciprocal link play the same role? Previous researches haven''t displayed a clear picture to us until now according to the best of our knowledge. Motivated by this, in this paper, we empirically study the influence of reciprocal links in two representative real datasets, Sina Weibo and Douban. Our results demonstrate that the reciprocal links play a more important role than non-reciprocal ones in information diffusion process. In particular, not only coverage but also the speed of the information diffusion can be significantly enhanced by considering the reciprocal effect. We give some possible explanations from the perspectives of network connectivity and efficiency. This work may shed some light on the in-depth understanding and application of the reciprocal effect in directed online social networks.     

线索有效性对社会性注意和外源性注意的影响

目的 眼睛注视、头朝向和生物运动方向等社会性线索,对人类的生存和社会交互极为重要.由于社会性线索和外周线索都具有反射性注意定向这一特点,社会性注意往往也被认为属于外源性注意.但是,外源性注意并不能完全解释所有的社会性注意现象.因此,两者是否具有相同的加工机制,尚存在争论.方法 本研究使用空间线索范式,系统考察了线索有效...     

Cortical and Hippocampal Correlates of Deliberation during Model-Based Decisions for Rewards in Humans

How do we use our memories of the past to guide decisions we''ve never had to make before? Although extensive work describes how the brain learns to repeat rewarded actions, decisions can also be influenced by associations between stimuli or events not directly involving reward — such as when planning routes using a cognitive map or chess moves using predicted countermoves — and these sorts of associations are critical when deciding among novel options. This process is known as model-based decision making. While the learning of environmental relations that might support model-based decisions is well studied, and separately this sort of information has been inferred to impact decisions, there is little evidence concerning the full cycle by which such associations are acquired and drive choices. Of particular interest is whether decisions are directly supported by the same mnemonic systems characterized for relational learning more generally, or instead rely on other, specialized representations. Here, building on our previous work, which isolated dual representations underlying sequential predictive learning, we directly demonstrate that one such representation, encoded by the hippocampal memory system and adjacent cortical structures, supports goal-directed decisions. Using interleaved learning and decision tasks, we monitor predictive learning directly and also trace its influence on decisions for reward. We quantitatively compare the learning processes underlying multiple behavioral and fMRI observables using computational model fits. Across both tasks, a quantitatively consistent learning process explains reaction times, choices, and both expectation- and surprise-related neural activity. The same hippocampal and ventral stream regions engaged in anticipating stimuli during learning are also engaged in proportion to the difficulty of decisions. These results support a role for predictive associations learned by the hippocampal memory system to be recalled during choice formation.     

The Influence of Chronic and Situational Social Status on Stereotype Susceptibility

We tested whether stereotypical situations would affect low-status group members'' performance more strongly than high-status group members''. Experiment 1 and 2 tested this hypothesis using gender as a proxy of chronic social status and a gender-neutral task that has been randomly presented to favor boys (men superiority condition), favor girls (women superiority condition), or show no gender preference (control condition). Both experiments found that women’s (Experiment 1) and girls’ performance (Experiment 2) suffered more from the evoked stereotypes than did men''s and boys’ ones. This result was replicated in Experiment 3, indicating that short men (low-status group) were more affected compared to tall men (high-status group). Additionally, men were more affected compared to women when they perceived height as a threat. Hence, individuals are more or less vulnerable to identity threats as a function of the chronic social status at play; enjoying a high status provides protection and endorsing a low one weakens individual performance in stereotypical situations.     

Influence of Ecological and Social Factors on Body Mass of Wild Chimpanzees

The chimpanzees (Pan troglodytes schweinfurthii) of Gombe National Park, Tanzania, were weighed regularly over a period of 33 yr, resulting in 1286 measurements on 31 males and 26 females aged 2–43 yr. Female growth slowed at 10 yr and that of males at 13 yr. Median adult body mass is 39 kg for males and 31.3 kg for females. Body mass varied between years. Chimpanzees were heaviest during a period of frequent banana provisioning. They were also heavier when community range size was large and population density within the range was low. Chimpanzees were heavier in the wet than in the dry season and body mass tracked rainfall in the preceding mo except for May in which mass was anomalously low. Dominance rank is significantly correlated with body mass for females but not males. High-ranking individuals tended to maintain more stable mass. Variability in body mass was greater for young and old individuals than for prime adults.     

Rewards and the evolution of cooperation in public good games

Properly coordinating cooperation is relevant for resolving public good problems, such as clean energy and environmental protection. However, little is known about how individuals can coordinate themselves for a certain level of cooperation in large populations of strangers. In a typical situation, a consensus-building process rarely succeeds, owing to a lack of face and standing. The evolution of cooperation in this type of situation is studied here using threshold public good games, in which cooperation prevails when it is initially sufficient, or otherwise it perishes. While punishment is a powerful tool for shaping human behaviours, institutional punishment is often too costly to start with only a few contributors, which is another coordination problem. Here, we show that whatever the initial conditions, reward funds based on voluntary contribution can evolve. The voluntary reward paves the way for effectively overcoming the coordination problem and efficiently transforms freeloaders into cooperators with a perceived small risk of collective failure.     

Influence of Personal Social Network and Coping Skills on Risk for Suicidal Ideation in Chinese University Students

Background

Personal social network and coping skills have important influences on suicidality of young people and such influences must be understood in the context of other factors. This study aims to assess the influences of social contacts and coping skills on risk for suicidal ideation and to disentangle their possible pathways using a large sample of university students from China.

Methods

5972 students, randomly selected from 6 universities in China, completed the questionnaire survey for the study. Logistic regression was performed to estimate individual effect of social contacts and coping skills on risk for suicidal ideation. A partial least squares path model (PLSPM) was used to probe possible paths of their effects in the context of psychopathology.

Results

Of the 5972 students, 16.39% reported the presence of suicidal ideation. Poor social contacts were significantly associated with an increased risk for suicidal ideation. The influence of coping skills varied by coping styles adapted toward problems. A high score of skills on seeking guidance and support, problem solving as well as seeking alternative rewards was associated with a reduced risk of suicidal ideation; whereas a high score of acceptance or resignation, emotional discharge as well as logical analysis was associated with a significantly increased risk. Modeling the data with PLSPM indicated that the avoidance coping skills conferred the most important dimensional variable in suicidal ideation prediction, followed by the approach coping skills and social network.

Conclusions

Poor social contacts and deficient coping skills are strong risk factors for suicidal ideation in young students. Prevention program focusing on these problems may have an enduring effect on reducing suicidal behavior in this population.     

超声波处理对淫羊藿苷生物转化的影响

利用超声波技术分别对淫羊藿苷粗品及淫羊藿苷转化发酵液进行处理,探讨超声波处理对淫羊藿苷生物转化效果的影响。经过超声波处理的实验组与未经超声波处理的对照组相比,转化效果显著提高;高效液相色谱图显示经超声波处理后淫羊藿苷峰几乎消失,苷元峰突出,超声波处理对淫羊藿苷生物转化效果影响很大。本研究确定超声波的最佳处理条件为频率40kHz,时间30min。     

The Influence of Social Systems on Patterns of Mitochondrial DNA Variation in Baboons

Behavior is influenced by genes but can also shape the genetic structure of natural populations. Investigating this link is of great importance because behavioral processes can alter the genetic diversity on which selection acts. Gene flow is one of the main determinants of the genetic structure of a population and dispersal is the behavior that mediates gene flow. Baboons (genus Papio) are among the most intensely studied primate species and serve as a model system to investigate the evolution of social systems using a comparative approach. The general mammalian pattern of male dispersal and female philopatry has thus far been found in baboons, with the exception of hamadryas baboons (Papio hamadryas). As yet, the lack of data on Guinea baboons (Papio papio) creates a taxonomic gap in genus-wide comparative analyses. In our study we investigated the sex-biased dispersal pattern of Guinea baboons in comparison to hamadryas, olive, yellow, and chacma baboons using sequences of the maternally transmitted mitochondrial hypervariable region I. Analyzing whole-range georeferenced samples (N = 777), we found strong evidence for female-biased gene flow in Guinea baboons and confirmed this pattern for hamadryas baboons, as shown by a lack of genetic-geographic structuring. In addition, most genetic variation was found within and not among demes, in sharp contrast to the pattern observed in matrilocal primates including the other baboon taxa. Our results corroborate the notion that the Guinea baboons’ social system shares some important features with that of hamadryas baboons, suggesting similar evolutionary forces have acted to distinguish them from all other baboons.