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.     

自我框架、风险认知和风险选择

对行为决策中“框架效应”(Framing Effect)的研究进行了拓展：探讨了自我框架对风险决策的影响及其机制。面对运用图示方法表示的管理,健康,及投资方面的风险决策问题,参与者自主地选择对方案的描述（自我框架）。研究有四个主要发现：1）自我框架对风险选择的效应部分显著,而且对风险选择的影响方向因情境的不同而不同;2）机会威胁认知是自我框架效应的一个中介变量;3）自我框架在情绪语气上的差异对风险决策有显著影响：决策者对一个备选方案（确定性或风险性方案）相对于另一个备选方案的自我描述的情绪语气越积极正面,这个方案被选择的可能性越大;4）决策者的机会-威胁认知是这一自我框架效应的部分中介变量。也就是说,对备选方案的自我描述语气作为一种对决策信息的编码影响了风险（机会和威胁）认知,进而影响决策者的风险偏好和选择     

心理距离对跨期选择和风险选择的影响

通过考察时间距离、社会距离和概率距离对跨期选择和风险选择的影响, 探究跨期选择和风险选择心理过程的相似性, 并检验不同心理距离影响决策的相似性。结果发现, 无论是时间距离(实验1)、社会距离(实验2)、还是概率距离(实验3), 心理距离越远, 被试在跨期选择中越倾向于延迟选项, 在风险选择中越倾向于风险选项。研究认为, 在跨期选择和风险选择中, 选项的表征结构和选项整体评价时不同选项特征的相对权重具有相似性。随着心理距离增加, 与高识解相联系的金额特征的相对权重增加, 与低识解相联系的时间和概率特征的相对权重降低, 这使得被试更倾向于选择金额较大的延迟和风险选项。同时, 研究发现三类心理距离对两类决策有相似影响, 进一步验证了不同心理距离的本质相似性。     

识解水平对跨期选择和风险选择的影响

通过考察识解水平启动对跨期选择和风险选择的影响, 探究两类选择对时间或风险心理加工的相似性。结果发现, 无论以思维诱导为识解水平的启动条件(实验1), 还是以视觉加工为识解水平的启动条件(实验2), 受高识解水平启动的被试对延迟选项和风险选项的主观值判断都要大于受低识解水平启动的被试, 说明跨期选择中的延迟时间和风险选择中的概率具有相似的表征, 而识解水平思维定势是通过影响金额和时间(或概率)的相对权重起作用。即由于高识解水平下的金额权重高于低识解水平, 时间(或概率)权重低于低识解水平, 从而使被试在高识解水平下更愿意等待或冒险。     

情感启发式对风险选择的影响

本研究旨在考察情感启发式对风险选择的影响。研究1采用线上和线下结合的方式对687名大学生进行问卷施测,修订并检验中文版情感启发式问卷的信效度,以该问卷测试的风险−收益相关系数作为衡量情感启发式倾向的指标。研究2采用极端被试法,在103名大学生完成问卷后,将风险−收益相关系数绝对值前20%和后20%的被试分为高、低情感启发式组,完成风险选择任务。结果发现：（1）中文版情感启发式问卷具有较好的信度与效度,可以作为情感启发式倾向的测试问卷。（2）风险选择任务激活负性情绪时,相比于低情感启发式倾向,高情感启发式倾向的被试更容易受负性情绪的影响,其风险判断的主观值更高。研究揭示了情感启发式对风险选择的影响,为情感启发式作为个体进行风险判断的重要依据提供了实证支持。     

风险条件下的跨期选择

跨期选择是指对发生在未来不同时间点上的结果做出权衡的决策过程。由于大部分跨期选择的情景都处于某种风险之中, 把风险变量纳入跨期选择的研究中则至为关键。针对以往研究在研究范围、理论构建、现实意义等诸方面的不足, 本研究拟采用实验室实验与纸笔测验相结合的方法, 深入揭示高、中、低三种概率水平下风险对跨期选择的影响特征, 探索其发生的机制、各类经典效应的大小。在此基础上, 根据全国不同地区的大样本调查结果, 了解各地区风险条件下跨期选择的差异及其与本地宏观经济指标(如, 消费者物价指数)的关联, 进而探讨研究的现实意义。本研究期望对风险条件下的跨期选择做出系统、全面的科学探索, 并为国家相关部门制定政策提供有价值的参考。     

People Wait Longer when the Alternative is Risky: The Relation Between Preferences in Risky and Inter‐temporal Choice

In two experiments, we demonstrate that despite indicating indifference when probed about risk or delay in isolation, when forced to explicitly trade‐off between the two, participants prefer delayed over risky rewards. This pattern of findings sets a boundary condition for any common utility‐based comparison process involving both risk and delay. Furthermore, this change from indifference‐in‐isolation to delay‐preference‐in‐a‐trade‐off strengthens as reward amount increases. Exploratory modeling results suggest that the shift in preference can be explained by allowing for different discount rates for delay‐only choices compared with when delay is in competition with risk. This explanation is better than one in which probability weighting is different between risk‐only choices and risks considered in the presence of a delay. Together, the empirical and modeling work lays a path for future investigations of why and when people's evaluation of the properties of risky and delayed choices vary as a function of the alternatives on offer. Copyright © 2017 John Wiley & Sons, Ltd.     

Behavioral and pharmacological variables affecting risky choice in rats.

The effects of manipulations of response requirement, intertrial interval (ITI), and psychoactive drugs (ethanol, phencyclidine, and d-amphetamine) on lever choice under concurrent fixed-ratio schedules were investigated in rats. Responding on the "certain' lever produced three 45-mg pellets, whereas responding on the "risky" lever produced either 15 pellets (p = .33) or no pellets (p .67). Rats earned all food during the session, which ended after 12 forced trials and 93 choice trials or 90 min, whichever occurred first. When the response requirement was increased from 1 to 16 and the ITI was 20 s, percentage of risky choice was inversely related to fixed-ratio value. When only a single response was required but the ITI was manipulated between 20 and 120 s (with maximum session duration held constant), percentage of risky choice was directly related to length of the ITI. The effects of the drugs were investigated first at an ITI of 20 s, when risky choice was low for most rats, and then at an ITI of 80 s, when risky choice was higher for most rats. Ethanol usually decreased risky choice. Phencyclidine did not usually affect risky choice when the ITI was 20 s but decreased it in half the rats when the ITI was 80 s. For d-amphetamine, the effects appeared to he related to baseline probability of risky choice; that is, low probabilities were increased and high probabilities were decreased. Although increase in risky choice as a function of the ITI is at variance with previous ITI data, it is consistent with foraging data showing that risk aversion decreases as food availability decreases. The pharmacological manipulations showed that drug effects on risky choice may be influenced by the baseline probability of risky choice, just as drug effects can be a function of baseline response rate.     

The living legacy of the Harvard Pigeon Lab: quantitative analysis in the wide world

From the Harvard Pigeon Lab of the 1960s arose a behavior-analytic approach that was quantitative and rigorous, rooted in Herrnstein's matching law. Researchers modified the matching law to describe choice behavior in a variety of different settings and examined its relations with other quantitative models. Beginning in the early 1970s, researchers began using the Harvard Pigeon Lab's quantitative framework to study in the laboratory specific aspects of the world outside the laboratory. Much of this work concerned investigations of self-control-choice of a larger, more delayed reinforcer over a smaller, less delayed reinforcer. Experiments using a quantitative framework derived from the matching law have also been conducted outside the laboratory; however, these have been far less frequent. Current and future researchers will benefit the field by devising new, creative ways to investigate the matching law and related quantitative models outside the laboratory. Such research can help to demonstrate the validity of these models as basic principles of behavior, can enhance public opinion of and rewards for such research, and can stimulate further development of the Harvard Pigeon Lab's quantitative approach by using that approach with new variables.     

确定、不确定及风险状态下选择反转:“齐当别”选择方式的解释

应用广义“弱优势”（weak dominance）模型检验确定、不确定及风险状态下的选择反转现象。该模型将人们的二择一选择行为描述为一种搜寻一备择方案在主观上优越于另一备择方案的过程。即：在甲方案在某一维度上优越于乙方案,而乙方案在另一维度上优越于甲方案的情况下,为了利用“弱优势”（weak dominance）原则达成决策,人们必须在一维度上将两者间较小的差异人为地“齐同”掉,而在另一维度上将“辨别”两者间较大的差异作为最终选择的依据。因此,在每次选择时,如果不认为最大的差异都是来自同一维度,就会导致选择反转。此项研究设计了一“匹配”任务,并借此检验,在不同的决策状态下,判断两备择方案在各维度上的差异是否能预测人们的重复选择变异。总的测试-再测试结果支持“齐当别”选择方式的解释。其发现表明：重复选择之所以可能是一致的,并不是因为每次都认定被选中的备择方案具有最大值,而是因为每次选择都认定最大的差异来自一固定的维度。     

Strategy Selection in Risky Choice: The Impact of Numeracy,Affect, and Cross‐Cultural Differences

Real‐world decisions often involve options with outcomes that are uncertain and trigger strong affect (e.g., side effects of a drug). Previous work suggests that when choosing among affect‐rich risky prospects, people are rather insensitive to probability information, potentially compromising decision quality. We modeled the strategies of less and more numerate participants in the United States and in Germany when choosing between affect‐rich prospects and between monetarily equivalent affect‐poor prospects. Using large probabilistic national samples (n = 1047 from the United States and Germany), Study 1 showed that compared with more numerate participants, less numerate participants chose the normatively better option (i.e., the one with the higher expected value) less often, guessed more often, and relied more on a simple risk‐minimizing strategy. U.S. participants—although less numerate—selected the normatively better option more frequently and were more consistent across affect‐rich and affect‐poor problems than the German participants. Using a targeted quota sample (n = 118 from Germany), Study 2 indicated that although both more and less numerate participants paid less attention to probability information in affect‐rich than in affect‐poor problems, the two numeracy groups relied on different outcome‐based heuristics: More numerate participants often followed the minimax heuristic, and less numerate participants the affect heuristic. The observed strategy differences suggest that attempts to improve decision‐making need to take into account individual differences in numeracy as well as cultural‐specific experiences in making trade‐offs. Copyright © 2012 John Wiley & Sons, Ltd.     

Human risky choice under temporal constraints: tests of an energy-budget model

Risk-sensitive foraging models predict that choice between fixed and variable food delays should be influenced by an organism's energy budget. To investigate whether the predictions of these models could be extended to choice in humans, risk sensitivity in 4 adults was investigated under laboratory conditions designed to model positive and negative energy budgets. Subjects chose between fixed and variable trial durations with the same mean value. An energy requirement was modeled by requiring that five trials be completed within a limited time period for points delivered at the end of the period (block of trials) to be exchanged later for money. Manipulating the duration of this time period generated positive and negative earnings budgets (or, alternatively, "time budgets"). Choices were consistent with the predictions of energy-budget models: The fixed-delay option was strongly preferred under positive earnings-budget conditions and the variable-delay option was strongly preferred under negative earnings-budget conditions. Within-block (or trial-by-trial) choices were also frequently consistent with the predictions of a dynamic optimization model, indicating that choice was simultaneously sensitive to the temporal requirements, delays associated with fixed and variable choices on the upcoming trial, cumulative delays within the block of trials, and trial position within a block.     

“All‐or‐None” Versus “Most‐or‐Some” Options in Risky Choice: Effects of Domain and Handedness

Two methodological variants of Kahneman and Tversky's Asian disease scenario were investigated. One variant involved replacing the “all‐or‐none” outcome scenarios of the risky choice with “most‐or‐some” scenario outcomes, and the second variant involved replacing the negative domain of lives lost with a positive domain of jobs created. In addition, the effects of strength of handedness, a variable related to individual differences in risk perception, were examined. Results indicated that standard framing effects were obtained across both domains, with a decrease in risky choice under the gain domain. Scenario type also interacted with handedness, such that the all‐or‐none scenario yielded framing effects for consistent (strong)‐handers only, whereas the most‐or‐some scenario yielded framing effects for inconsistent (mixed)‐handers only (consistent‐handers are those who use the same hand exclusively for almost all activities). These results demonstrate that framing effects are strongly influenced by the presence versus absence of extreme/absolute outcomes and that individuals (in this case, decision makers with varying degrees of handedness strength) are differentially sensitive to different pieces of information. Copyright © 2014 John Wiley & Sons, Ltd.     

How Affect Shapes Risky Choice: Distorted Probability Weighting Versus Probability Neglect

People's choices between prospects with relatively affect‐rich outcomes (e.g., medical side effects) can diverge markedly from their choices between prospects with relatively affect‐poor outcomes (e.g., monetary losses). We investigate the cognitive mechanisms underlying this “affect gap” in risky choice. One possibility is that affect‐rich prospects give rise to more distortion in probability weighting. Another is that they lead to the neglect of probabilities. To pit these two possibilities against each other, we fitted cumulative prospect theory (CPT) to the choices of individual participants, separately for choices between options with affect‐rich outcomes (adverse medical side effects) and options with affect‐poor outcomes (monetary losses); additionally, we tested a simple model of probability neglect, the minimax rule. The results indicated a qualitative difference in cognitive mechanisms between the affect‐rich and affect‐poor problems. Specifically, in affect‐poor problems, the large majority of participants were best described by CPT; in affect‐rich problems, the proportion of participants best described by the minimax rule was substantially higher. The affect gap persisted even when affect‐rich outcomes were supplemented by numerical information, thus providing no support for the thesis that choices in affect‐rich and affect‐poor problems diverge because the information provided in the former is nonnumerical. Our findings suggest that the traditional expectation‐based framework for modeling risky decision making may not readily generalize to affect‐rich choices. Copyright © 2015 John Wiley & Sons, Ltd.     

Multiple Framing: Verbal,Facial, and Vocal Cues in Risky Choice

Verbal framing effects have been widely studied, but little is known about how people react to multiple framing cues in risk communication, where verbal messages are often accompanied by facial and vocal cues. We examined joint and differential effects of verbal, facial, and vocal framing on risk preference in hypothetical monetary and life–death situations. In the multiple framing condition with the factorial design (2 verbal frames × 2 vocal tones × 4 basic facial expressions × 2 task domains), each scenario was presented auditorily with a written message on a photo of the messenger's face. Compared with verbal framing effects resulting in preference reversal, multiple frames made risky choice more consistent and shifted risk preference without reversal. Moreover, a positive tone of voice increased risk‐seeking preference in women. When the valence of facial and vocal cues was incongruent with verbal frame, verbal framing effects were significant. In contrast, when the affect cues were congruent with verbal frame, framing effects disappeared. These results suggest that verbal framing is given higher priority when other affect cues are incongruent. Further analysis revealed that participants were more risk‐averse when positive affect cues (positive tone or facial expressions) were congruently paired with a positive verbal frame whereas participants were more risk‐seeking when positive affect cues were incongruent with the verbal frame. In contrast, for negative affect cues, congruency promoted risk‐seeking tendency whereas incongruency increased risk‐aversion. Overall, the results show that facial and vocal cues interact with verbal framing and significantly affect risk communication. Copyright © 2016 John Wiley & Sons, Ltd.     

Choice and the rate of punishment in concurrent schedules

Rats' responses on two levers were reinforced according to independent random-interval 1.5-min food schedules. In addition, both lever presses were intermittently punished according to several concurrent random-interval random-interval shock schedules. For the left, the scheduled rate of punishment was kept constant according to a random-interval 6-min schedule. For the right, the rate of punishment varied. As the frequency of punishment for the right lever press increased, its rate decreased. The rate of the left punished lever press increased, however, even though its scheduled reinforcement rate and punishment rate remained unchanged.     

Human group choice: discrete-trial and free-operant tests of the ideal free distribution

Ideal free distribution theory predicts that foragers will form groups proportional in number to the resources available in alternative resource sites or patches, a phenomenon termed habitat matching. Three experiments tested this prediction with college students in discrete-trial simulations and a free-operant simulation. Sensitivity to differences in programmed reinforcement rates was quantified by using the sensitivity parameter of the generalized matching law (s). The first experiment, replicating prior published experiments, produced a greater degree of undermatching for the initial choice (s = 0.59) compared to final choices (s = 0.86). The second experiment, which extended prior findings by allowing only one choice per trial, produced comparable undermatching (s = 0.82). The third experiment used free-operant procedures more typical of laboratory studies of habitat matching with other species and produced the most undermatching (s = 0.71). The results of these experiments replicated previous results with human groups, supported predictions of the ideal free distribution, and suggested that undermatching represents a systematic deviation from the ideal free distribution. These results are consistent with a melioration account of individual behavior as the basis for group choice.     

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。     

Human choice in concurrent ratio-interval schedules of reinforcement.

Seven undergraduates participated in a concurrent-choice experiment with monetary reinforcers. Response-independent analogues of variable-interval and variable-ratio schedules were used to assess whether subjects would maximize reinforcement rate. The optimal pattern of behavior, in terms of maximizing reinforcement rate, involved a large bias toward the ratio alternative, with only occasional sampling of the interval schedule. Most experiments with pigeons, however, demonstrate matching of response rates to reinforcement rates, with only slight biases for the ratio schedule. Although subjects in the present experiment allocated more time to the ratio alternative than required by matching, the magnitude of the bias did not approximate that predicted by a maximizing account. After exposure to clock stimuli correlated with the operation of each schedule, 1 subject's behavior did show a substantial level of bias, increasing the total number of reinforcers obtained, and lay at a point between the predictions of matching and maximizing. The other subjects, however, continued to respond less optimally. The present results can be accounted for by a view of matching that incorporates the effects of delayed reinforcement.