Situational factors contributing to the placebo effect

The influence of four variables (status of communicator of drug effects, attitude of dentist, attitude of dental technician, and message of drug effects) on the obtainment of placebo effects in an oral surgery clinic was investigated. Dependent variables were (1) rating of pain experienced from mandibular-block injection, (2) pre-post placebo state anxiety, and (3) pre-postplacebo fear of injection. Enthusiastic messages of drug effects produced statistically and clinically significant reductions in postplacebo fear of injection and state anxiety and markedly lower ratings of pain experienced during injection of local anesthetic. Although there was a strong tendency for positive placebo effects to occur when the dental staff was perceived as friendly and supportive, only the attitude factors obtained statistical significance. The status of the communicator accounted for very small portions of the variance.This investigation was conducted in the Oral Surgery Clinic of Ben Taub General Hospital, Houston, Texas     

Ten Years' Experience Conducting the Aging Game Workshop: Was It Worth It?

In the Aging Game, medical students experience simulated physical, sensory, and cognitive deficits that are associated with disability from chronic diseases. Since 1994, the University of Minnesota has presented an innovative version of the Aging Game as part of the curriculum in a required clinical clerkship. The experiences conducting the Aging Game over the past decade were reviewed, focusing on the resources necessary to produce it and on its worth as an educational tool. Because many of the reusable props were obtained free as donations, start-up material costs were calculated at 530 dollars. Personnel necessary for each half-day presentation of the Aging Game included two faculty and a minimum of five nonfaculty serving as facilitators; a staff coordinator was also essential. Quantitative student evaluations (N=673) exhibited mean ratings of 1.41, 1.35, and 1.40 (1=excellent) for overall value, teaching effectiveness, and quality of a postsimulation discussion. Written student comments regarding the strengths of the Aging Game centered on three major themes: mode of learning, especially using role playing and simulating deficits (total of 192 comments); attitudinal change, specifically raising awareness and stimulating reflection on the experiences of disabled older adults (121 comments); and educational value, particularly the Aging Game's capacity for creating a memorable impression (56 comments). Despite consuming significant personnel resources, the Minnesota version of the Aging Game is an effective tool for stimulating long-lasting awareness and understanding of key issues related to aging and geriatrics.     

Relationship between platelet serotonin content and rejections of unfair offers in the ultimatum game

The ultimatum game (UG), a well-studied decision task used in experimental neuroeconomics, represents a simple two-person bargaining between a proposer and a responder. The proposer offers the responder how to split a sum of money. The responder decides whether to accept or reject the offer. When the responder accepts it, each player earns money according to the proposer's offer. If the offer is rejected, neither player gets anything. Rejections of “free” money in the UG represent a deviation from the standard economic model of rationality. This behaviour could be linked to adverse psychological reactions to unfair offers, including anger, hostility and impulsiveness. Currently, it is believed that the most plausible biological system related to anger and impulsivity is the serotonergic system. We hypothesize that serotonergic activity, as measured by platelet serotonin levels, will differentiate subjects who either reject or accept low UG offers. A sample of 60 economy students (31 males and 29 females, mean age: 24.4 ± 2.3 years) was investigated. As predicted, the mean platelet serotonin level was significantly lower in participants who reject unfair offers (€1 out of €10) than in those who accept (2.86 ± 0.13 versus 3.48 ± 0.11 nmol/10⁹ platelets, respectively, p < 0.001). We conclude that low platelet serotonin may serve as a reliable biomarker to identify people who are more likely to reject unfair ultimatum offers in an experimental neuroeconomic setting. Our pilot data seem to indicate that the serotonergic system may play an important role in the UG rejection behaviour.     

Herd behavior in a complex adaptive system

In order to survive, self-serving agents in various kinds of complex adaptive systems (CASs) must compete against others for sharing limited resources with biased or unbiased distribution by conducting strategic behaviors. This competition can globally result in the balance of resource allocation. As a result, most of the agents and species can survive well. However, it is a common belief that the formation of a herd in a CAS will cause excess volatility, which can ruin the balance of resource allocation in the CAS. Here this belief is challenged with the results obtained from a modeled resource-allocation system. Based on this system, we designed and conducted a series of computer-aided human experiments including herd behavior. We also performed agent-based simulations and theoretical analyses, in order to confirm the experimental observations and reveal the underlying mechanism. We report that, as long as the ratio of the two resources for allocation is biased enough, the formation of a typically sized herd can help the system to reach the balanced state. This resource ratio also serves as the critical point for a class of phase transition identified herein, which can be used to discover the role change of herd behavior, from a ruinous one to a helpful one. This work is also of value to some fields, ranging from management and social science, to ecology and evolution, and to physics.     

Dynamic social networks promote cooperation in experiments with humans

Human populations are both highly cooperative and highly organized. Human interactions are not random but rather are structured in social networks. Importantly, ties in these networks often are dynamic, changing in response to the behavior of one's social partners. This dynamic structure permits an important form of conditional action that has been explored theoretically but has received little empirical attention: People can respond to the cooperation and defection of those around them by making or breaking network links. Here, we present experimental evidence of the power of using strategic link formation and dissolution, and the network modification it entails, to stabilize cooperation in sizable groups. Our experiments explore large-scale cooperation, where subjects' cooperative actions are equally beneficial to all those with whom they interact. Consistent with previous research, we find that cooperation decays over time when social networks are shuffled randomly every round or are fixed across all rounds. We also find that, when networks are dynamic but are updated only infrequently, cooperation again fails. However, when subjects can update their network connections frequently, we see a qualitatively different outcome: Cooperation is maintained at a high level through network rewiring. Subjects preferentially break links with defectors and form new links with cooperators, creating an incentive to cooperate and leading to substantial changes in network structure. Our experiments confirm the predictions of a set of evolutionary game theoretic models and demonstrate the important role that dynamic social networks can play in supporting large-scale human cooperation.     

Eating Disorders and Their Putative Risk Factors Among Female German Professional Athletes

This study examines putative non‐sport‐specific and sport‐specific risk factors for eating disorders (ED) among groups of professional female athletes versus non‐athletes. In detail, societal pressure to be thin, its internalisation, body dissatisfaction, sports pressure and early specialisation were investigated. The cross‐sectional study included 46 aesthetic and 62 ball game sports athletes, and 108 age‐matched non‐athletes. Study methods comprised a clinical interview to detect ED and questionnaires. More athletes from aesthetic (17%) than from ball game sports (3%) and non‐athletes (2%) suffered from ED. Aesthetic sports athletes did not differ from non‐athletes in non‐sport‐specific factors but obtained higher levels than ball game sports athletes in sport‐specific variables (p < .01). All factors together accounted for 57.3% of variation in disordered eating, with sports pressure and body dissatisfaction as significant predictors. The results confirm ED risk for German aesthetic athletes and indicate the importance of sports pressure and body dissatisfaction in explaining athletes' vulnerability. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.     

Collapse of cooperation in evolving games

Game theory provides a quantitative framework for analyzing the behavior of rational agents. The Iterated Prisoner’s Dilemma in particular has become a standard model for studying cooperation and cheating, with cooperation often emerging as a robust outcome in evolving populations. Here we extend evolutionary game theory by allowing players’ payoffs as well as their strategies to evolve in response to selection on heritable mutations. In nature, many organisms engage in mutually beneficial interactions and individuals may seek to change the ratio of risk to reward for cooperation by altering the resources they commit to cooperative interactions. To study this, we construct a general framework for the coevolution of strategies and payoffs in arbitrary iterated games. We show that, when there is a tradeoff between the benefits and costs of cooperation, coevolution often leads to a dramatic loss of cooperation in the Iterated Prisoner’s Dilemma. The collapse of cooperation is so extreme that the average payoff in a population can decline even as the potential reward for mutual cooperation increases. Depending upon the form of tradeoffs, evolution may even move away from the Iterated Prisoner’s Dilemma game altogether. Our work offers a new perspective on the Prisoner’s Dilemma and its predictions for cooperation in natural populations; and it provides a general framework to understand the coevolution of strategies and payoffs in iterated interactions.Iterated games provide a framework for studying social interactions (1–6) that allows researchers to address pervasive biological problems such as the evolution of cooperation and cheating (2, 7–12). Simple examples such as the Iterated Prisoner’s Dilemma, Snowdrift, and Stag Hunt games (13–18) showcase a startling array of counterintuitive social behaviors, especially when studied in a population replicating under natural selection (16, 19–25). Despite the subject’s long history, a systematic treatment of all evolutionary robust cooperative outcomes for even the simple Iterated Prisoner’s Dilemma has only recently emerged (21, 26–29).Understanding the evolution of strategies in a population under fixed payoffs already poses a steep challenge. To complicate matters further, in many biological settings the payoffs themselves may also depend on the genotypes of the players. Changes to the payoff matrix have been studied in a number of contexts, including one-shot two-player games (13), payoff evolution without strategy evolution (30, 31), under environmental “shocks” to the payoff matrix (32–34), and using continuous games (22, 23, 35). Here we adopt a different approach, and we explicitly study the coevolutionary dynamics between strategies and payoffs in iterated two-player games. We decouple strategy mutations from payoff mutations, and we leverage results on the evolutionary robustness of memory-1 strategies with arbitrary payoff matrices to explore the relationship between payoff evolution and the prevalence of cooperation in a population. We identify a feedback between the costs and benefits of cooperation and the evolutionary robustness of cooperative strategies. Depending on the functional form (35) of the relationship between costs and benefits, this feedback may either reinforce the evolutionary success of cooperation or else precipitate its collapse. In particular, we show that cooperation will always collapse when there are diminishing returns for mutual cooperation.     

Teaching Geriatrics Using an Innovative,Individual‐Centered Educational Game: Students and Educators Win. A Proof‐of‐Concept Study

Given the increasingly aging population, nearly every doctor will encounter elderly adults who present with multiple complex comorbidities that can challenge even experienced physicians. This may explain why many medical students do not have a positive attitude toward elderly adults and find the complexity of their problems overwhelming. It was hypothesized that a recently developed medical school geriatrics course, based on the game GeriatriX and designed specifically to address the complexities associated with decision‐making in geriatrics, can have a positive effect on attitudes toward geriatrics and on perceived knowledge of geriatrics. The effects of this game‐based course were evaluated as a proof of concept. The assessment was based on the Aging Semantic Differential (ASD) and a validated self‐perceived knowledge scale of geriatric topics. The usability of (and satisfaction with) GeriatriX was also assessed using a 5‐point Likert scale. After completion of the course, the ASD changed significantly in the geriatrics course group (n = 29; P = .02) but not in a control group that took a neuroscience course (n = 24; P = .30). Moreover, the geriatrics course group had a significant increase in self‐perceived knowledge for 12 of the 18 topics (P = .002), whereas in the control group self‐perceived knowledge increased significantly for one topic only (sensory impairment) (P = .04). Finally, the geriatrics students reported enjoying GeriatriX. This proof‐of‐concept study clearly supports the hypothesis that a 4‐week course using a modern educational approach such as GeriatriX can improve students' self‐perceived knowledge of geriatrics and their attitudes toward elderly adults.     

基于团队定位分工模式的情景模拟培训在心肺复苏中的应用

目的探讨基于团队定位分工模式的情景模拟教学在心肺复苏实践中的应用。方法将57名护士按能级及专科技能分A,B,C 3个级别,不同级别的3名护士与1名医生组成的4人抢救小组,进行团队式情景模拟心肺复苏培训,比较实施前后抢救小组开始心肺复苏到建立静脉通路、连接心电监护建立人工气道、首次给入复苏药物的时间以及危重患者抢救质量评分;医生对护士抢救的综合满意度,护士对工作的满意度情况。结果培训后建立静脉通路、连接心电监护、建立人工气道以及首次给入复苏药物的时间较培训前均明显缩短,危重患者抢救质量检查评分明显提高,差异有统计学意义(P<0.05);医生对护士抢救的综合满意度提高,护士对工作满意度由85.97%提高到95.26%。结论基于团队定位分工模式情景模拟教学的实施有利于提高护士的团队配合能力,缩短各项抢救措施的落实时间,提高医生对护士抢救的综合满意度,以及护士对工作的满意度。