When bonuses backfire: an inaction inertia analysis of procrastination induced by a missed opportunity

An inaction inertia analysis of procrastination was used to generate the prediction that using bonuses to encourage early task completion will have two opposing effects, encouraging early task completion by some but also inducing procrastination for those who miss the bonus. Study 1 showed that the addition of bonuses for early completion produced both of these effects and also led to overall task completion rates that were either equal to (large bonus) or actually less than (medium and small bonuses) those obtained by simply establishing a completion deadline with no bonus. In Study 2, a lottery methodology was used to manipulate the size of a missed bonus for all participants. Even under these conditions of reduced personal responsibility the larger missed bonus led to increased procrastination as predicted by the inaction inertia analysis. Possible mediating processes based on anticipated regret and perceived fairness were discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

The impact of variability and prechoice experience on taking safety measures: The case of security updates

The goal of this research is to clarify the conditions that trigger reluctance to take cost-effective safety measures. We present three experiments. In two of the experiments, the participants were asked to operate a simulated system for 20 periods, each with 10 trials. They could “update the system” to eliminate the risk of a “security failure” that led to a loss of 100 points. The updating cost was either fixed (at 10 points) or variable (initially 10 points, and some probability of free—0 points—updates). The optimal strategy prescribed updating at the first opportunity. Another experiment focused on one-shot decision under risk. The results highlight two factors that reduce the tendency to update and impair performance: cost variability and prechoice experience. Importantly, we show that the negative impact of cost variability is the product of two tendencies. First, experiencing periods with free updates slowed learning to select the optimal policy. Second, in many cases, the participants behaved as if they plan to update when the cost of updating is low but forget to do so. The results suggest that security can be enhanced by asking users to select a default updating policy before gaining experience and by replacing “free updates” with automatic updates. Information concerning the existence of automatic updates reduced manual updating, but this effect was eliminated by experience.     

Behavioral shifts after a fatal rapid transit accident: A multinomial logit model

The Washington, DC Metrorail collision in 2009 presents a rare opportunity to study rapid transit passengers’ responses to a highly publicized rail incident entailing injuries and fatalities. To investigate behavioral responses to the accident, particularly mode shifts, we conducted a web-based survey of approximately 300 commuters traveling on Metrorail after the accident who had used Metrorail in the 6 months prior to the collision. The most common response to the accident was avoidance of the first and last train cars. Some respondents substituted some Metrorail trips with other modes or took fewer Metrorail trips. To investigate factors influencing these behavioral responses, we employ multinomial logit models to explore the statistical association between respondent and travel characteristics and the choice among the options of (1) making no changes, (2) avoiding certain seating locations, (3) changing modes of transportation, and (4) changing both seating locations and modes of transportation. Results suggest that travel inertia, specifically mode inertia, exists, in that respondents generally prefer not to make mode or travel choice changes. However, some mode characteristics, such as cost differences and frequent delays have a statistically significant association with mode switching. Gender and the presence of children in the household correlate with the option selected.     

Mass Perturbation of a Body Segment: I. Effects on Segment Dynamics

Investigators often use mass perturbation of body segments as an experimental paradigm to study movement coordination. To analyze the effect of mass perturbation on small-amplitude oscillations, the authors linearize the equation of motion of a single segment moving in a vertical plane and derive the effect of added mass on the undamped eigenfrequency, the relative damping, and the low-frequency control gain of the segment. Mass addition results in a decrease in both the relative damping and the low-frequency control gain; the undamped eigenfrequency increases for mass addition between the pivot point and R₀ (where R₀ is the length of a point mass pendulum whose undamped eigenfrequency is identical to that of the unperturbed segment), decreases for mass addition beyond R₀, and remains unaffected for mass addition at R₀. For a typical lower leg + foot segment, R₀ is just proximal to the ankle joint. That location may explain the absence of an effect on oscillation frequency in studies in which mass has been added to the ankle. The authors' analysis provides a basis for a more effective application of mass perturbations in future experiments.     

黎明模拟光照对晨起睡眠惰性的影响

本研究采用单因素被试内设计对清晨唤醒后睡眠惰性对个体主观情绪、警觉性和认知加工的影响，以及利用动态黎明模拟光照能否对睡眠惰性产生有效的对抗作用进行了考察。结果发现：（1）被试的积极情绪、主观警觉性在刚唤醒时显著低于基线水平，之后随时间推移逐渐提升。（2）被试醒后立即进行测试的认知加工成绩最差，随后逐渐提高，且主要表现在加工速度的回升上。（3）黎明模拟光照对被试醒后在积极情绪、主观警觉性、持续性注意和抑制功能的缓解上产生了明显的促进作用。这表明睡眠惰性会对个体的主客观活动产生显著的负性影响，而使用黎明模拟光照可在一定程度上对抗睡眠惰性带来的负性影响。     

Microstructural integrity of the corpus callosum linked with neuropsychological performance in adolescents

Background: Diffusion tensor imaging (DTI) has revealed microstructural aspects of adolescent brain development, the cognitive correlates of which remain relatively uncharacterized. Methods: DTI was used to assess white matter microstructure in 18 typically developing adolescents (ages 16–18). Fractional anisotropy (FA) and mean diffusion (MD) were evaluated within the splenium and body of the corpus callosum in relation to cognitive performance. Results: Visuospatial construction abilities were associated with white matter integrity in both the splenium and body of the corpus callosum, while only splenium integrity was associated with language and psychomotor function. Conclusion: Results suggest that, for typically developing adolescents, white matter coherence positively relates to visuospatial, psychomotor, and language skills. These findings may have implications for the cognitive functioning of clinical populations in which typical white matter development is altered.     

Effects of alcohol,rumination, and gender on the time course of negative affect

This study modelled associations between gender, ruminative cognitive style, alcohol use, and the time course of negative affect over the course of 43,111 random assessments in the natural environment. Participants (N?=?263) completed 49 days of experience sampling over 1.3 years. The data indicated that rumination at baseline was positively associated with alcohol dependence symptoms at baseline as well as higher negative affect over the course of the study. Consistent with negative reinforcement models, drinking served to decrease the persistence of negative affect from moment to moment. However, this ameliorative effect of drinking was evident only among women, suggesting an increased risk for negative reinforcement driven drinking behaviour. In addition, rumination appeared to counteract the desired effects of alcohol on mood among women. This suggests that women who ruminate more may be motivated to consume larger amounts of alcohol to achieve the desired effects. Overall, the results indicate that ruminative cognitive style and the persistence of negative affect from moment to moment may reflect an individual vulnerability for the development of alcohol use disorder especially among women.     

扩散张量成像在脑胶质瘤诊治中的应用

扩散张量成像是目前唯一可以在活体显示大脑内白质纤维走向的磁共振成像技术,对于脑胶质瘤术前诊断,制定手术计划,指导手术及判定预后等方面是非常有帮助的。综述了近年来扩散张量成像技术在脑胶质瘤诊断、治疗及判定预后中的应用价值,并结合文献提出了目前存在的不足。     

运动空间定向判断中的方向偏差及飞行惯性

模拟客体起飞和降落运动,探讨飞行场景中不同运动位置、不同意义客体和运动方向下个体运动空间定向判断能力。结果表明：(1)对降落运动轨迹的判断正确率显著低于起飞运动;(2)无意义客体偏高轨迹的判断正确率显著小于偏低轨迹,表现出方向偏差;(3)飞行场景影响方向偏差的表现形式,当飞机降落运动时,易将偏低路径判断为与预设轨迹相同,而飞机起飞运动时,易将偏高路径判断为相同,表明降落时飞机被知觉为会向斜下方越飞越低,而起飞时飞机会向斜上方越飞越高,表现出飞行惯性。结论：运动空间定向判断受到重力表征及个体知识经验等共同影响,具有认知可渗透性。     

On the determination of defect dipoles from atomistic simulations using periodic boundary conditions

By solving the problem of a periodic distribution of point defects in general anisotropic media, we give an alternative, more direct proof, of the relatively recent procedure that extracts dipole tensors from the stress acting on the cell of atomistic simulations performed under periodic boundary conditions. Moreover, we show that naive superposition of individual defect fields is not a solution of the problem, though correction terms can be identified; as a byproduct, analysis of the latter allows us to reveal a spurious contribution to the elastic interaction energy as calculated in current literature procedures, that therefore must be subtracted in order to obtain correct results.