Processes Mediating Judgements of Likelihood

可能的判断在几乎所有生活领域的决策中起着至关重要的作用。 通常，当已知可能发生不止一个备选事件时，人们必须判断一个事件的可能性（例如，病人患A类疾病而不是B、C或D类疾病的可能性;建筑工程合同授予投标人F而不是G或H的可能性;朋友乘坐K航班而不是M或L航班的可能性）。 拟议中的研究将揭示这种可能性判断背后的基本过程。 主要研究者最近的研究表明，对可能性的判断通常是通过一种独特的比较启发式来进行的;这种判断在很大程度上取决于焦点事件和最强的替代事件的证据强度之间的比较，而不是对焦点事件的证据与所有替代事件的证据的总和进行加权。 比较启发式非常有效，通常能产生合理的可能性判断。然而，这种启发式也可能是与标准概率论的规范性规定不一致的感知可能性模式的基础。 九个实验将研究比较启发式的性质、强度和范围。 他们还将研究在日常判断情况下变化的任务条件--时间压力，被请求的响应类型，以及可用证据的可量化性--如何影响可能性判断。 实验将涉及广泛的范式和判断类型。 各种方法工具（例如，对可供选择的结果的分布的操纵，过程跟踪）将允许在实验的操纵条件下评估慎思过程与启发式过程的相对影响。 这一研究应该大大推进对可能性判断过程的理解，并增强研究人员基于对具有多个选择的焦点事件的感知来预测判断（以及决策和行为）的能力。

Likelihood judgment plays a critical role in decisions that are made inalmost all of life's domains. Often, people must judge the likelihood ofone event when more than one alternative event is known to be possible(e.g., the likelihood that a patient has condition A rather than conditionB, C, or D; the likelihood that a contract for a construction project willbe awarded to bidder F rather than G or H; the likelihood that a friend isarriving on airline K rather than M or L). The proposed research willexamine fundamental processes underlying such likelihood judgments. Recentresearch by the primary investigator suggests that judgments of likelihoodare often mediated by a distinct comparison heuristic; such judgments arelargely dependent upon a comparison between the strength of the evidencefor the focal event and the strongest alternative event, rather than aweighing of the evidence for the focal event versus the aggregate of theevidence for all alternative events. The comparison heuristic is veryefficient and generally produces reasonable judgments of likelihood.However, the heuristic can also underlie patterns of perceived likelihoodthat are not consistent with the normative dictates of standard probabilitytheory. Nine experiments will investigate the nature, strength, and scopeof the comparison heuristic. They will also examine how task conditionsthat vary under everyday judgment situations--time pressure, the type ofresponse being solicited, and the quantifiability of the availableevidence--influence likelihood judgments. The experiments will involve awide range of paradigms and judgment types. Various methodological tools(e.g., manipulations to the distributions of alternative outcomes, processtracing) will allow for an assessment of the relative influence ofdeliberative versus heuristic processes within manipulated conditions ofthe experiments. This research should substantially advance theunderstanding of processes mediating judgments of likelihood as well asenhance researchers' abilities to predict judgments (and decisions andbehaviors) that are based on perceptions of focal events that have multiplealternatives.