睡眠剥夺对风险决策的影响机制探讨

许多行业的决策者必须在睡眠不足的状态下做出选择与判断。睡眠剥夺是睡眠不足的实验室模型, 被证明能显著影响风险决策, 但内在机制不明。基于前人研究基础提出假设模型, 即睡眠剥夺通过影响个体的反馈加工、风险感知、抑制控制、决策理性, 进而影响风险决策。拟通过实验室研究与现场研究, 采用简单赌博任务、概率折扣任务、双选择Oddball任务等研究范式, 对比睡眠剥夺前后被试在执行上述实验任务时的行为差异, 同时比较执行控制网络、奖赏网络等脑功能网络连接强度, 以及任务诱发的FRN等脑电成分在睡眠剥夺前后的变化, 进而论证上述反应被试反馈加工等心理过程的行为-脑电-脑成像指标的变化与睡眠剥夺后被试风险决策变化的关系。研究结果将科学地解释睡眠剥夺影响风险决策的内在机制, 为进一步探讨如何规避睡眠不足导致的决策失误提供理论与实证依据。     

元认知中自信心对联合决策的预测作用

元认知通常指个体对自身认知活动的主观判断, 自信心作为其指标之一, 对个体认识和调节自己的行为有重要作用。研究表明自信心指标在联合研究过程中常见的任务类型涉及基础和高级心理加工过程, 此外, 自信心对联合决策的预测逐渐向基于计算模型的探索性参数变化。最后, 自信心的神经生理研究发现了前额叶皮层及其相关脑区和后顶叶皮层的重要性。今后应注重探索可能的预测参数和模型, 优化自信心对联合决策的预测作用。     

健康领域的跨期决策与健康行为

健康领域的跨期决策关系着个体和国民的健康和福祉。目前学界对该领域的研究主要停留在参考传统金钱领域的相关理论模型和方法的阶段, 但健康跨期决策具有领域特异性, 沿袭金钱领域理论模型和方法, 导致该领域在研究方法和结果上存在较大的不一致性。健康跨期决策的行为后果是该领域关注重点, 多数研究均报告个体的低时间折扣率、高未来时间取向与其健康保护行为正相关, 与健康风险行为呈负相关。该领域也关注健康跨期决策的影响机制, 如决策对象和决策主体的核心特征等因素。未来研究亟需发展适用于健康领域的跨期决策模型和研究范式, 明确健康行为与跨期决策偏好的关系, 深入探讨健康跨期决策的内在选择机制, 并在健康行为干预和医疗卫生政策应用方面进行更多的尝试和探索。     

Post-decision consolidation: group members in different social settings compared to individual decision makers

Two experiments were conducted to examine how making decisions in a 3-member group affects the degree of post-decision consolidation, defined as attractiveness changes in favor of the chosen alternative. Both experiments were conducted in two sessions one week apart. In the first session (decision phase), participants estimated the importance of each of four different attributes describing two decision alternatives. They were then shown predetermined attractiveness ratings on each of the attributes and were to decide on the two alternatives, either individually or as a group. In the second session (post-decision phase), the participants were to attempt to recall the attractiveness ratings for the attributes as presented to them in session one. In both experiments, significant post-decision consolidation was found for individual decision makers but not for group members. In experiment 2, this result was replicated, no difference in consolidation being found between group members with face-to-face interaction and without.     

Individual postdecision processes in group settings

In two experiments Differentiation and Consolidation Theory (Diff Con) (Svenson, 1992) was used to investigate individual postdecision making processes in three-member groups. It was predicted that in groups in which the subjects preferred different alternatives (conflict groups), subjects would consolidate their own preferred alternative, and not the group's final decision. A second hypothesis was that no consolidation would be indicated in groups in which all members preferred the same alternative (non-conflict groups). The results showed that in conflict groups, the members who gave up their preferred alternative (minority members) consolidated their own preference, thereby significantly regretting the group decision. In contrast, members who got their own will through in the majority decision (majority members) showed no consolidation of the group decision. The corresponding pattern of results was replicated in a second experiment, using a different decision situation. The results indicated that perceptions of social support, agreement in a group and decreasing responsibility for a group's decision, could all partly substitute consolidation by attractiveness restructuring.     

Postdecision consolidation in a trend prediction task

To be able to learn from experience it is necessary to correctly apprehend experienced feedback and the situation in which it is provided. The results indicate how post-decision consolidation in complex domains may affect learning. The problem may be particularly pertinent in recurrent decision making where considerable risk is involved. The study explores the changes in aspect (signal) importance from pre- to postdiction as a function of outcome information. By postdiction we mean the remembering of an earlier prediction (cf. Hawkins & Hastie, 1990). Subjects were asked to decide on which of four alternative future price developments would follow a historical price trajectory for different commodities, and to rate the importance of each of the chosen alternative's corresponding aspects. The subjects revealed a bias in their support ratings of aspects--seeing support in aspects that traditionally (by themselves and in many contexts) would be seen as neutral or even counter-indicative of the alternative chosen. After an intermission, the subjects were also given information about what was indicated to be the actual development of the market. One group was told that their decisions were correct (irrespective of what the decisions were), another group that they were incorrect but close, a third group that they were incorrect by far, while a fourth group served as a control. Following this information the subjects were again asked to judge the importance of the aspects for their own prior decision on the most likely future development. The results indicated that outcome feed-back had an effect on post decision restructuring of facts. Subjects in the correct condition showed an average consolidation that increased the support, while the wrong conditions lead to negative consolidation (in retrospect indicating that they never found as much support for their decision in the past as they actually did). Thus, in a choice between consolidating their own initial prediction and the price trajectory they would have to live with, the decision makers consolidated the outcome. Therefore, the results of the study were related to the hindsight bias phenomenon (Fischhoff, 1975) and to Kahneman and Miller's (1986) mutability concept.     

Prefrontal brain activity predicts temporally extended decision-making behavior

Although functional neuroimaging studies of human decision-making processes are increasingly common, most of the research in this area has relied on passive tasks that generate little individual variability. Relatively little attention has been paid to the ability of brain activity to predict overt behavior. Using functional magnetic resonance imaging (fMRI), we investigated the neural mechanisms underlying behavior during a dynamic decision task that required subjects to select smaller, short-term monetary payoffs in order to receive larger, long-term gains. The number of trials over which the longterm gains accrued was manipulated experimentally (2 versus 12). Event-related neural activity in right lateral prefrontal cortex, a region associated with high-level cognitive processing, selectively predicted choice behavior in both conditions, whereas insular cortex responded to fluctuations in amount of reward but did not predict choice behavior. These results demonstrate the utility of a functional neuroimaging approach in behavioral psychology, showing that (a) highly circumscribed brain regions are capable of predicting complex choice behavior, and (b) fMRI has the ability to dissociate the contributions of different neural mechanisms to particular behavioral tasks.     

On Modal μ-Calculus and Non-Well-Founded Set Theory

A finitary characterization for non-well-founded sets with finite transitive closure is established in terms of a greatest fixpoint formula of the modal -calculus. This generalizes the standard result in the literature where a finitary modal characterization is provided only for wellfounded sets with finite transitive closure. The proof relies on the concept of automaton, leading then to new interlinks between automata theory and non-well-founded sets.     

Semantic gender assignment regularities in German

Gender assignment relates to a native speaker's knowledge of the structure of the gender system of his/her language, allowing the speaker to select the appropriate gender for each noun. Whereas categorical assignment rules and exceptional gender assignment are well investigated, assignment regularities, i.e., tendencies in the gender distribution identified within the vocabulary of a language, are still controversial. The present study is an empirical contribution trying to shed light on the gender assignment system native German speakers have at their disposal. Participants presented with a category (e.g., predator) and a pair of gender-marked pseudo-words (e.g., der Trelle vs. die Stisse) preferentially selected the pseudo-word preceded by the gender-marked determiner "associated" with the category (e.g., masculine). This finding suggests that semantic regularities might be part of the gender assignment system of native speakers.