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.     

睡眠剥夺影响风险决策的双系统模型探讨

睡眠剥夺是指由于环境或自身原因无法满足正常睡眠时间的情况。大量实证研究发现, 睡眠剥夺会导致个体在风险决策中更倾向于风险寻求, 同时也有研究表明睡眠剥夺会导致个体风险规避, 而目前尚无统一结论。睡眠剥夺从风险感知、风险容忍、风险决策策略三个方面影响了风险决策, 其心理机制可由认知和情绪双路径模型进行解释, 且脑神经生理学研究也提供了相关证据。未来的研究应该进一步关注：(1)现实工作生活中的睡眠不足对风险决策的影响; (2)睡眠剥夺影响风险决策的理论模型建构。     

投资决策进化心理学的研究：预期的私人资金分配和父母对子女的差异性精力投入

投资决策的进化心理学研究着眼于辨认人类获得进化适应的特定环境中经常出现的典型性风险,探寻为了应对这些风险而进化出的信息处理机制,并验证现时的社会因素和个体因素对这些心理机制的激活或抑制作用。在研究一中,被试预测了与自己同龄的男人或女人如何分配一笔中彩的奖金给自己和其他可能的受益人。研究发现：（1）钱数的分配大体由亲缘关系的疏密程度决定;（2）两性被试都假想男性比女性更慷慨,但实际上男性表现得更自利;（3）女性被试预测男性中奖人的金钱分配比男性被试预测女性中奖人的金钱分配更为准确;（4）女性被试的受益人更多,分享的社会范围更广。研究二探讨了父母对子女投入精力的不同取决于家庭的相对财富而非绝对财富的进化心理学假说。用哺乳与否和生育间隔期为测量指标,研究结果显示：（1）家庭实际收入影响父母对子女的总投入;（2）与邻里家庭相比,父母对于自己家庭相对收入的认知影响了对子女有别的差异性精力投入。基于男性普遍在财富和生育数量上比女性有更大的变异度,投资儿子比投资女儿更具博弈性。两项研究表明,人类的理性决策既受限于社会关系又适应于相对的财富状况     

Pervasiveness of framing effects among physicians and medical students

Researchers have been documenting the influence of framing upon decision making for more than two decades; decisions appear to change in response to superficial changes in the presentation of possible outcomes. Several studies of medical decision making have revealed; for instance, that clinical decisions differ when options are presented as gains (survival rates) rather than losses (mortality rates). However, most studies of framing effects in the medical domain have utilized a very limited number of clinical problems that have not allowed an adequate test of the prevalence of the phenomena. To extend previous studies, we presented three groups of subjects (experienced internists, residents, and third-year medical students) with booklets containing twelve hypothetical medical cases. Half of the subjects received gain versions and half received loss versions of the same cases. Chi-square analyses revealed that framing did not influence any of the decisions of medical students and influenced the decisions of residents and experienced physicians on only two of the clinical problems (the same two problems). It appears that the prevalence of framing effects in the clinical domain may be limited.     

Risky choice as a function of amount and variance in food supply.

In Experiment 1, 4 rats earned their daily food ration by choosing on a trials basis between a "risky" and a "riskless" lever. The risky lever produced either 15 45-mg food pellets or no pellets, and on average provided five pellets per choice. The riskless lever always produced three pellets. Across conditions, the number of trials per session was varied. Body weight and choice of the risky lever decreased as the number of trials per session decreased, even though body weight could only be defended by increased choice of the risky lever. In Experiment 2, trials per session were fixed, but the number of pellets delivered by the risky and riskless levers was either at the same level as in Experiment 1 or tripled from those levels. Now choice of the risky lever was inversely related to the size of reinforcement and to body weight. The results of these experiments show that risk aversion covaries with the amount of food available in a session and the daily variance in the amount of food earned.     

To buy or to sell: cultural differences in stock market decisions based on price trends

Four studies compared the stock market decisions of Canadians and Chinese. In two studies using simple stock market trends, compared with Chinese, Canadians were more willing to sell and less willing to buy falling stock. But when the stock price was rising, the opposite occurred: Canadians were more willing to buy and less willing to sell. A third study showed that for complex stock price trends, Canadians were strongly influenced by the most recent price trends: they tended to predict that recent trends would continue and made selling decisions without considering the rest of the trend patterns; whereas the Chinese made reversal predictions for the dominant trends and made decisions that took both recent and early trends into consideration. Study 4 replicated the finding with experienced individual investors. These findings are consistent with the previous literature on different lay theories of change held by Chinese and North Americans. Copyright © 2008 John Wiley & Sons, Ltd.     

Children's preference for mixed‐ versus fixed‐ratio schedules of reinforcement: A translational study of risky choice

Laboratory research has shown that when subjects are given a choice between fixed‐ratio and bi‐valued mixed‐ratio schedules of reinforcement, preference typically emerges for the mixed‐ratio schedule even with a larger ratio requirement. The current study sought to replicate and extend these findings to children's math problem completion. Using an ABCBC reversal design, four fourth‐grade students were given the choice of completing addition problems reinforced on either a fixed‐ratio 5 schedule or one of three mixed‐ratio schedules; an equivalent mixed‐ratio (1, 9) schedule, a mixed‐ratio (1, 11) schedule with a 20% larger ratio requirement, and an equally lean mixed‐ratio (5, 7) schedule without the small fixed‐ratio 1 component. This was followed by a reversal back to the preceding phase in which preference for the mixed‐ratio schedule had been observed, and a final reversal back to the mixed‐ratio (5, 7) phase. Findings were consistent with previous research in that all children preferred the mixed‐ratio (1, 9) schedule over the equivalent fixed‐ratio 5 schedule. Preference persisted for the leaner mixed‐ratio (1, 11) schedule for three of the four children. Indifference or preference for the fixed‐ratio 5 alternative was observed in phases containing the mixed‐ratio (5, 7) schedule. These results extend previous research on risky choice to children's math problem completion and highlight the importance of a small ratio component in the emergence of preference for bi‐valued mixed‐ratio schedules. Implications of these results for arranging reinforcement to increase children's academic responding are discussed.     

Racial Bias in Decisions Made by Mock Jurors Evaluating a Case of Sexual Harassment

Abstract

White (N = 161) and Black (N = 152) college students served as mock jurors in a simulated civil case in which a female plaintiff accused a male defendant of sexual harassment. The authors experimentally manipulated the race (Black or White) of the litigants and asked the mock jurors to decide whether the defendant was guilty; to rate the certainty of their belief in the defendant's guilt; and, when they judged the defendant guilty, to recommend an award to the plaintiff. Mock jurors of both races tended to favor litigants of their own race and their own gender. Racial bias was highest among White male jurors and lowest among White female jurors.     

Protecting Against Low‐Probability Disasters: The Role of Worry

We carry out a large monetary stakes insurance experiment with very small probabilities of losses and ambiguous as well as exact probabilities. Many individuals do not want to pay anything for insurance whether the probabilities are given exactly or are ambiguous. Many others, however, are willing to pay surprisingly large amounts. With ambiguity, the percentage of those paying nothing is smaller and the willingness to pay (WTP) of the other individuals larger than with exact probabilities. Comparing elasticities with ambiguity, we find that worry is much more important than subjective probability in determining WTP for insurance. Furthermore, when the ambiguous loss probability is increased by a factor of 1000, it has almost no effect on WTP. Copyright © 2011 John Wiley & Sons, Ltd.     

Instance‐based Learning: A General Model of Repeated Binary Choice

A common practice in cognitive modeling is to develop new models specific to each particular task. We question this approach and draw on an existing theory, instance‐based learning theory (IBLT), to explain learning behavior in three different choice tasks. The same instance‐based learning model generalizes accurately to choices in a repeated binary choice task, in a probability learning task, and in a repeated binary choice task within a changing environment. We assert that, although the three tasks are different, the source of learning is equivalent and therefore, the cognitive process elicited should be captured by one single model. This evidence supports previous findings that instance‐based learning is a robust learning process that is triggered in a wide range of tasks from the simple repeated choice tasks to the most dynamic decision making tasks. Copyright © 2010 John Wiley & Sons, Ltd.