概率大小、损益结果和认知闭合需要对模糊规避的影响

模糊规避是指在相同奖赏的情况下,决策者会力图规避从主观上判断具有模糊概率的事件而偏好具有相同精确概率的事件。本研究探讨了概率大小、损益结果和认知闭合需要对模糊规避的影响。研究发现,在小概率受益的情况下,个体倾向于模糊寻求;在中概率受益的情况下,个体倾向于模糊规避;在高概率受益的情况下,个体倾向于模糊规避;在小概率损失的情况下,个体倾向于模糊规避;在中概率损失的情况下,个体倾向于模糊规避;在高概率损失的情况下,个体倾向于模糊寻求。但是,研究并未发现认知闭合需要对模糊规避有预测作用。     

模糊规避的形成机制：基于可评价性假设的视角

模糊规避是指在相同奖赏的情况下,决策者会力图规避从主观上判断具有模糊概率的事件而偏好具有相同精确概率的事件。本研究使用同时评价、单独评价的研究范式从随机事件和自然事件两个领域来探讨模糊规避的形成机制。研究结果表明,当风险事件和模糊事件同时评价时,个体倾向于模糊规避;当风险事件和模糊事件单独评价时,模糊规避会消失。     

Ambiguity Attitudes over Time

Previous research demonstrates that individuals exhibit a stronger level of ambiguity aversion for high probabilities than for low probabilities. Given that risky and ambiguous prospects are often unresolved until a future date (e.g., investment decisions, new product launches, and medical interventions), this study examines the impact of time on ambiguity preferences at different probability levels. Our experimental results indicate that although ambiguity preferences for low‐probability events remain constant, a robust effect of time occurs for high‐probability events. More specifically, temporal distance mitigates ambiguity aversion. This effect is consistent for different elicitation methods (preference rating and probability–ambiguity trade‐off tasks). We propose a dual‐process model (affective versus cognitive processing styles) to explain our results. Affective processing for high‐probability lotteries resolved in the current period increases ambiguity aversion, while cognitive processing leads to less ambiguity‐averse choices for future lotteries. Copyright © 2015 John Wiley & Sons, Ltd.     

The Effect of Temporal Distance on Attitudes toward Imprecise Probabilities and Imprecise Outcomes

Many personal, managerial, and societal decisions involve uncertain or ambiguous consequences that will occur in the future. Yet, previous empirical research on ambiguity preferences has focused mainly on decisions with immediate outcomes. To close this gap in the literature, this paper examines ambiguity attitudes toward future prospects, particularly how they may differ from the attitudes toward comparable prospects in the present. On the basis of a recent paradigm, we first distinguish between two types of ambiguity: imprecise probabilities and imprecise outcomes. Then, in accordance with construal level theory, which shows that temporal distance increases the relative importance of outcomes over probabilities in evaluating prospects, we conjecture that temporal distance would moderate attitudes toward imprecise probabilities but amplify attitudes toward imprecise outcomes. Through a series of experiments, we demonstrate that when the prospects are in the future, individuals are less averse toward imprecise probabilities and more seeking toward imprecise outcomes. However, the effect is most prominent for prospects where both the probability and outcome dimensions are concurrently imprecise. The paper ends with a discussion on how dimension salience may have contributed to this result. Copyright © 2012 John Wiley & Sons, Ltd.     

When and why do people avoid unknown probabilities in decisions under uncertainty? Testing some predictions from optimal foraging theory.

When given a choice between two otherwise equivalent options - one in which the probability information is stated and another in which it is missing - most people avoid the option with missing probability information (Camerer & Weber, 1992). This robust, frequently replicated tendency is known as the ambiguity effect. It is unclear, however, why the ambiguity effect occurs. Experiments 1 and 2, which separated effects of the comparison process from those related to missing probability information, demonstrate that the ambiguity effect is elicited by missing probabilities rather than by comparison of options. Experiments 3 and 4 test predictions drawn from the literature on behavioral ecology. It is suggested that choices between two options should reflect three parameters: (1) the need of the organism, (2) the mean expected outcome of each option; and (3) the variance associated with each option's outcome. It is hypothesized that unknown probabilities are avoided because they co-occur with high outcome variability. In Experiment 3 it was found that subjects systematically avoid options with high outcome variability regardless of whether probabilities are explicitly stated or not. In Experiment 4, we reversed the ambiguity effect: when participants' need was greater than the known option's expected mean outcome, subjects preferred the ambiguous (high variance) option. From these experiments we conclude that people do not generally avoid ambiguous options. Instead, they take into account expected outcome, outcome variability, and their need in order to arrive at a decision that is most likely to satisfy this need.     

Valuing information and options: an experimental study

Participants in four studies were faced with everyday‐life decision scenarios involving risk, such as purchasing an airline ticket whose price may change. They were asked to state their maximum willingness to pay (WTP) for resolving the uncertainty with either perfect information or an option. The two are strategically equivalent, therefore, should be valued in the same way. Across all experiments, individuals tend to value the option more than the information. In addition, the distributions of responses reveal frequent and gross violations of normative bounds. Contrary to normative predictions, no relationship is found between individuals' valuation of the gamble and their reported WTP for information or option. Furthermore, although participants pay attention to the probabilities of outcomes in valuing the gambles, they ignore the probabilities in valuing uncertainty resolution. Several reasoning heuristics that participants use to come up with a value of information are identified, and it appears that the Information and Option contexts tend to trigger different heuristics. Shift in reference point and regret are consistent with the Information–Option valuation discrepancy. Copyright © 2007 John Wiley & Sons, Ltd.     

Context affects the interpretation of low but not high numerical probabilities: A hypothesis testing account of subjective probability

Low numerical probabilities tend to be directionally ambiguous, meaning they can be interpreted either positively, suggesting the occurrence of the target event, or negatively, suggesting its non-occurrence. High numerical probabilities, however, are typically interpreted positively. We argue that the greater directional ambiguity of low numerical probabilities may make them more susceptible than high probabilities to contextual influences. Results from five experiments supported this premise, with perceived base rate affecting the interpretation of an event’s numerical posterior probability more when it was low than high. The effect is consistent with a confirmatory hypothesis testing process, with the relevant perceived base rate suggesting the directional hypothesis which people then test in a confirmatory manner.     

Robust Tolerance for Ambiguity

We argue first that "ambiguous prospects" should be defined in a way that is compatible with dictionary definitions and other technical uses of ambiguity. We then define an ambiguous prospect as a disjunction of risky prospects. Then to harmonize some findings in the literature we test the hypothesis that people are ambiguity indifferent up to moderate amounts of ambiguity and are ambiguity averse only for large amounts of ambiguity. To test the hypothesis we found probability equivalents to risk for prospects of varying degrees of ambiguity. Up to an ambiguity range of .7 the equivalents were near that of a normatively equivalent risky prospect while the equivalents of highly ambiguous prospects differed. We interpret the data in terms of competing desires for minimum effort and maximum accuracy.     

Managers' variance investigation decisions: an experimental examination of probabilistic and outcome ambiguity

Information ambiguity is prevalent in organizations and may influence management decisions. This study examines, given imprecise probabilities or outcomes, how managers decide which department's performance to investigate further when they are provided with performance benchmarks expressed in numerical intervals. Seventy‐nine MBA students participated in two experiments involving investigation decisions. We presented participants with interval benchmarks of a firm's expenses. Being below or above the benchmark should have been seen as equally negative. We found that, when facing outcome ambiguity, our participants consistently preferred to investigate further those departments whose performance was described as having an ambiguous outcome (when the outcome's range was centered either below or above the interval benchmark). However, when facing probabilistic ambiguity, there were two predominant choice patterns: consistently choosing to investigate the department whose performance is described with an ambiguous probability, or consistently choosing to investigate the department with unambiguous performance. To gain further insight, we conducted a follow‐up study collecting written protocols of participants' reasons for making choices involving ambiguous performance information. The results show that our participants displayed similar decision‐making processes when facing outcome ambiguity and probabilistic ambiguity. Copyright © 2001 John Wiley & Sons, Ltd.     

The role of competition and knowledge in the Ellsberg task

Ambiguity avoidance denotes people's preference for gambling situations with known over unknown, or ambiguous, probability distributions. In four experiments we provide evidence for the interaction between competitiveness and knowledge in Ellsberg's task, in which people have a choice between a risky box (distribution of balls known) and an ambiguous box (distribution of balls not known). If the situation is perceived as competitive (the experimenter or an opponent is responsible for composing the boxes) people avoid ambiguity by betting on the box with the known probability distribution. If the task is perceived as cooperative (a partner or friend is composing the boxes) people are indifferent toward ambiguity or even ambiguity seeking. In addition, we find that people expect their winning odds to be less than even in the ambiguous box. Copyright © 2003 John Wiley & Sons, Ltd.     

The effects of endowment on the demand for probabilistic information

Research shows that individuals are ambiguity averse: they choose unambiguous over equivalent ambiguous prospects and price them higher (either as buyers or sellers). Moreover, it is often assumed that ambiguity averse individuals are willing to pay an ambiguity premium for information that reduces ambiguity [Camerer, C. F., & Weber, M. (1992). Recent developments in modeling preferences: Uncertainty and ambiguity. Journal of Risk and Uncertainty, 5(4), 325–370]. However, when people are asked to exchange an ambiguous alternative in their possession for an equivalent unambiguous one, they prefer to retain the former [Roca, M., Hogarth, R. M., & Maule, A. J. (2006). Ambiguity seeking as a result of the status quo bias. Journal of Risk and Uncertainty, 32(3), 175–194]. We present three experiments investigating the economic effects of endowment on attitudes towards ambiguity and the ambiguity premium. The experiments, based on a [Becker, G., DeGroot, M., & Marschak, J. (1964). Measuring utility by a single-response sequential method. Science, 9, 3] procedure, show that the value attributed to ambiguity reducing information is substantially affected by the status quo of the individual.     

Impact of regulatory focus on ambiguity aversion

Although prior research has shown that some people prefer a risky to an ambiguous option, this study further proposes that people's regulatory focus (promotion vs. prevention) might influence their ambiguity aversion. Three experiments have tested whether people with promotion focus showed less ambiguity aversion than those with prevention focus: The first experiment revealed that, compared with chronically promotion‐focused individuals, prevention‐focused subjects preferred a risky to an ambiguous option. In the second experiment, priming of the subjects' goal orientations led to similar results. Experiment 3 demonstrated that participants showed less ambiguity aversion for the expected performance of an investment product representative of promotion (e.g., a stock fund) rather than one representative of prevention (e.g., a bond fund). In other words, people showed less preference for a bond fund when the probability distribution of its expected performance was unknown than when it was known, whereas they showed less preference difference between known and unknown probability distributions for the expected performance of a stock fund. This study has integrated research pertaining to regulatory focus and ambiguity aversion, and the results have confirmed that the impact of regulatory focus on ambiguity aversion is robust across different methods and decision tasks. Copyright © 2010 John Wiley & Sons, Ltd.     

Boundary effects of vague risk information on taxpayer decisions

In compliance decisions, the decision maker usually has only vague or ambiguous knowledge of the probability of being caught and the outcome (amount of penalty). An experiment is reported which extends work on effects of probability ambiguity by manipulating outcome ambiguity as well. When outcomes were limited to a bounded range and probabilities ranged between their natural boundaries [0, 1] in experimental tax decisions, symmetrical boundary effects were found in which vague estimates for both the probability and outcome dimensions caused vagueness aversion (and higher compliance) when the vague estimate was near the more favorable lower boundary of either dimension and vagueness seeking (and lower compliance) when the vague estimate was near the less favorable upper boundary. Probability and outcome vagueness effects were found to be independent of the vagueness of the other dimension, and vagueness effects were not systematically related to the level of the other dimension.The results suggest that a common cognitive process mediates the impact of vagueness on both dimensions. This may be a vagueness-adjustment process in which vague estimates are adjusted toward the middle of the bounded range, or a vagueness-preference process in which vague outcomes, and vague probabilities as well, are evaluated based on utility considerations, as though probability were a tangible commodity. For increasing compliance, the results suggest that risk information should be disseminated only when risks of punishment are relatively high. When risks are low, random enforcement techniques that enhance vagueness become more effective.     

Impact of educational intervention on willingness-to-pay for suicide prevention: a quasi-experimental study among university students in Japan

Many individuals show negative attitudes toward the use of taxes for suicide prevention. Activities that enhance knowledge and awareness of suicide and suicide prevention may increase willingness to pay (WTP) for suicide prevention. WTP is the amount that a consumer will pay for a product or service. The present study examined the influence of educational activities on enhancing knowledge and awareness of suicide and its prevention on WTP. We conducted a quasi-experimental study to examine the influence of lectures on suicide by comparing the amount of change in WTP between two groups over the same period: an intervention group (n = 92) comprising students who participated in the lectures and a control group (n = 128) comprising general university students recruited through an Internet-based survey. A t-test showed that the amount of change was significantly larger in the intervention group (t (152.31) = 2.25, p = .026). Ordinal logistic regression analysis showed that increased WTP was significantly correlated with an annual household income of JPY 4–6 million or higher. It may be appropriate to conclude that participation in lectures about suicide is effective in increasing WTP for suicide prevention.     

Pricing risk and ambiguity: The effect of perspective taking

In the valuation of uncertain prospects, a difference is often observed between selling and buying perspectives. This paper distinguishes between risk (known probabilities) and ambiguity (unknown probabilities) in decisions under uncertainty and shows that the valuation disparity increases under ambiguity compared to risk. It is found that both the comparative versus noncomparative evaluation of risky and ambiguous prospects and the uniqueness of the valuation perspective (either seller or buyer) moderate this increase in the disparity under ambiguity. The finding is consistent with recent theoretical accounts of pricing under uncertainty. We discuss implications for market behaviour and for the ambiguity paradigm as a research tool.     

不确定性容忍度对模糊决策中决策偏好的影响及其情景依赖性*

研究以Ellsberg选瓶任务为决策材料,探讨了不同任务特征下个体不确定性容忍度对模糊决策中决策偏好的影响。结果发现,获益情景下:高概率时高、低容忍度个体对模糊选项的选择无显著差异,均偏好模糊规避;中概率时低容忍度个体比高容忍度个体表现出更低程度的模糊规避,前者倾向于模糊中立,后者倾向于模糊规避;低概率时两者对模糊选项的选择无显著差异,均倾向于模糊中立。损失情景下:高概率时两者对模糊选项的选择无显著差异,均倾向于模糊寻求;中概率时低容忍度比高容忍度个体更偏好模糊寻求,前者倾向于模糊寻求,后者倾向于模糊中立;低概率时两者对模糊选项的选择无显著差异,均倾向于模糊规避。这表明,不确定性容忍度对模糊决策偏好产生作用,但这种作用会受到损益概率和损益结果的影响,具有情景依赖性。     

Pricing risk and ambiguity: the effect of perspective taking

In the valuation of uncertain prospects, a difference is often observed between selling and buying perspectives. This paper distinguishes between risk (known probabilities) and ambiguity (unknown probabilities) in decisions under uncertainty and shows that the valuation disparity increases under ambiguity compared to risk. It is found that both the comparative versus noncomparative evaluation of risky and ambiguous prospects and the uniqueness of the valuation perspective (either seller or buyer) moderate this increase in the disparity under ambiguity. The finding is consistent with recent theoretical accounts of pricing under uncertainty. We discuss implications for market behaviour and for the ambiguity paradigm as a research tool.     

Attributions for ambiguity in a treatment-decision context can create ambiguity aversion or seeking

The phenomenon of ambiguity aversion suggests that people prefer options that offer precisely rather than imprecisely known chances of success. However, past work on people's responses to ambiguity in health treatment contexts found ambiguity seeking rather than aversion. The present work addressed whether such findings reflected a broad tendency for ambiguity seeking in health treatment contexts or whether specific attributions for ambiguity play a substantial role. In three studies, people choose between two treatment options that involved similar underlying probabilities, except that the probabilities for one option involved ambiguity. The attributions offered for the ambiguity played an important role in the results. For example, when the range of probabilities associated with an ambiguous treatment was attributed to the fact that different studies yield different results, participants tended to show ambiguity aversion or indifference. However, when the range was attributed to something that participants could control (e.g., regular application of a cream) or something about which they were overoptimistic (e.g., their immune system function), participants tended to show ambiguity seeking. Health professionals should be mindful of how people will interpret and use information about ambiguity when choosing among treatments.     

When do peers influence adolescent males' risk taking? Examining decision making under conditions of risk and ambiguity

Risk taking is highly prevalent among adolescent males, and a range of studies have shown that decisions become riskier if a peer is present. However, previous studies have typically provided participants with explicit probabilities of risk in each situation. This does not accurately reflect adolescents' real‐world risk taking, where decisions are made in ambiguous situations alongside their peers. Aiming for a more ecologically valid design, the present experiment manipulated situational ambiguity and examined its interplay with group decision making and developmental factors. Adolescent males (N = 202) aged 12–15 completed a “Wheel of Fortune” task and then self‐reported their score, presenting an opportunity to cheat as a measure of antisocial risk taking. As predicted, adolescents were more likely to take risks when probabilities were ambiguous rather than explicit. Further, higher levels of gambling choices were made by groups in ambiguous, but not risk situations. Age significantly predicted gambling in ambiguous conditions, whereas developmental dispositions (risk perception, reward sensitivity, and inhibitory control) did not play a role. Findings provide an insight into the social and situational conditions under which adolescent males engage in reckless behavior.