Linda问题:"齐当别"抉择模型的解释

大量有关人类归因判断的研究表明,人类经常违反理性概率公理.Tversky和Kahneman(1983)使用Linda问题等特定场景的研究发现,人们系统性地表现出违反理性推断标准,判断合取事件发生概率大于其组成事件发生概率,称之为合取谬误,并用人们使用代表性启发式判断概率来解释该现象产生的原因.然而使用启发式观点对合取谬误现象进行解释过于模糊不清.该文首先介绍了合取谬误现象及其解释模型,然后应用Li(1994,2004)提出的不确定情形下决策理论--"齐当别"抉择模型对Linda问题中合取谬误产生的原因进行了新的解释.     

概率判断中的合取谬误

概率判断中的合取谬误是指违反事件发生概率的合取规则而认为包含多个独立事件的复合事件的发生可能性大于其中某些事件的发生可能性的一种概率判断偏差现象。合取谬误的界定存在一定争议, 相关的解释机制有因果模型理论、确认理论、惊奇理论等, 影响合取谬误的因素有频率效应、训练效应以及个体差异等等。未来研究应联系逆转合取谬误的心理机制来完善已有的理论, 同时注意应用研究以及其非理性的探讨。     

认知需要和警告类型对合取谬误的影响

合取谬误是一种常见的判断偏差,它指的是在不确定条件下,个体评估合取事件及其简单事件发生的概率时,对合取规则系统性偏离的一种现象.实验1 就认知需要类型对合取谬误的影响进行探讨,结果发现高认知需要的被试较不易表现出双重合取谬误和单合取谬误.实验2 探讨了警告类型对合取谬误的影响,结果发现无警告时个体最易表现出单合取谬误,其次是间接警告,最后是直接警告;此外,认知需要与警告类型的交互作用显著,高认知需要的被试在直接警告和间接警告时更少表现出双重合取谬误,在直接警告时更少表现出单合取谬误.     

概念范畴情境化视角下的Linda问题初探

摘 要：本文首先提出了Linda问题的概念范畴情境化视角。该视角认为,Linda问题中的T与F的范畴与分别同T&F中T与F的范畴并不一定相同,当T&F中的T和F至少有一者的范畴较相应的T或F有较大的扩大,且同时另外一者至少较相应T或F有略微的扩大时,就有可能导致T&F>T或T&F>F为合理判断而非谬误的情形,因而至少不能将所有的T&F>或T&F>F的判断都归为谬误。本文通过三项研究发现,被试对T&F中T与F和T与F的专业性判断并不完全相同;排除女权的专业性合取事件<女权的专业性独立呈现且出纳的专业性合取事件<出纳的专业性独立呈现者,所谓谬误水平显著下降;对Linda问题的排序项增加“专业的或职业的”限定词,以增加相应概念范畴的稳定性,显著减少合取谬误。这些结果说明,Linda问题的概念范畴情境化视角获得了支持。     

个体证券投资者自我效能感对赌徒谬误的影响

赌徒谬误指当某一独立随机事件发生后,人们倾向认为这一结果再次出现的概率降低。如果一连串的随机事件呈现出一定的趋势,人们倾向于认为随机事件将呈现系统性反转。证券市场中的赌徒谬误指在股票上涨（下跌）序列中做出股价将要下跌（上涨）的判断。本研究探讨股票市场特征（趋势长度及方向）及投资者的人格特征（自我效能感）对赌徒谬误的影响。以83名股票投资者为对象,采用多层线性模型进行分析,结果发现：趋势长度主效应显著,短线情境下赌徒谬误频次更高;趋势方向主效应显著,下跌情境下赌徒谬误频次更高;二者交互作用显著,在短线下跌情境下,赌徒谬误频次更高;投资者的自我效能感对股票趋势长度具有调节作用,高自我效能的投资者在短线情境下更容易出现赌徒谬误。     

Linda问题的表象-命题双表征解释视角探究

本文首先提出了Linda问题的表象-命题双表征这一新的解释视角。该视角认为,Linda问题基于表象表征和命题表征可以有两种不同的解读与表征方式;而不同的被试在Linda问题上可能分别采取了上述表征方式之一;但由于Linda问题的特殊性,大多数被试采用了表象表征;大多数被试的这一表征取向则可能是所谓谬误判断出现的原因。本文通过4项研究,让被试在基于表象表征设计的转述版本与基于命题表征设计的转述版间选择接近自身理解的版本;并考察了将Linda问题修改成更符合命题表征的数学化表达形式能否降低所谓谬误水平;还考察了增加促使被试运用命题表征的排序项"Linda是全人类中的一员"能否降低所谓谬误水平。结果显示,在转述版本选择上,大多数被试选择了基于表象表征设计的版本;而上文所指的两个修正版Linda问题则都降低了被试的所谓谬误水平。这些结果支持了本文所提的视角。     

单结果多原因情况下的因果判断研究

本研究以直接呈现每种因果类型的频次的方式考察单结果多原因情况下影响因果判断的因素,同时检验概率对照模型,效力PC理论和因果模型理论。结果发现：（1）影响因果判断的因素有：事件原因与促进条件的性质差异,原因的熟悉度,原因和结果的共变程度;（2）同题抽象性对因果判断没有影响;（3）概率对照模型和因果模型理论在一定的情况下适用,但是都不能解释所有的情况。     

任务情境与概率知识经验对中学生合取判断的影响研究

本研究采用了一套由不同任务情境(数字情境和日常情境)组成的合取判断问卷与一套概率基础知识问卷,对106名中学生的合取判断情况进行调查,结果显示:(1)无论在哪种任务情境下,概率知识经验均未对合取判断成绩产生显著影响。(2)不同概率知识经验的被试在数字任务情境下采用的策略有所不同。     

行为决策中出现的分离效应

分离效应（the disjunction effect）是指：当决策者知道事件E会发生,他会采取行动A;当知道事件E不会发生,他仍会采取行动A;而当不知道事件E是否会发生的情况下,他会拒绝行动A。这一现象违背了理性决策理论的确定事件原则（sure-thing principle）。对分离效应的解释主要有基于理由的假设、思维惰性假设和齐当别模型。分离效应是否真的存在以及应该采用何种实验设计来进行研究都还有待进一步探讨。2005年诺贝尔经济学奖获得者Aumann对事件分离情境和事件非分离情境的区分,为进一步研究分离效应指明了新的方向。理解分离效应及其成因有利于人们做出“理性”的决策     

一种新决策模型——量子决策模型

近10年以来, 一些学者基于量子理论研究思想与方法探索出了量子决策模型。由于该模型独特的理论结构, 它可被用于解释传统决策理论所难以解释的问题, 尤其是个体在不确定情况下的决策行为。该模型解释了诸如分离效应、分类决策的干涉效应以及合取谬误等传统决策模型很难解释的问题, 研究者已经证实其中一种称为量子问题等式的决策模型可以精确地预测决策中的顺序效应。作为一个有助于分析心理学中决策现象的新研究领域, 量子决策模型具有深入研究的理论意义和实践意义。     

On the nature of the conjunction fallacy

In a seminal work, Tversky and Kahneman showed that in some contexts people tend to believe that a conjunction of events (e.g., Linda is a bank teller and is active in the feminist movement) is more likely to occur than one of the conjuncts (e.g., Linda is a bank teller). This belief violates the conjunction rule in probability theory. Tversky and Kahneman called this phenomenon the “conjunction fallacy”. Since the discovery of the phenomenon in 1983, researchers in psychology and philosophy have engaged in important controversies around the conjunction fallacy. The goal of this paper is to explore the most important of these controversies, namely, the controversy about the nature of the conjunction fallacy. Is the conjunction fallacy mainly due to a misunderstanding of the problem by participants (misunderstanding hypothesis) or is it mainly due to a genuine reasoning bias (reasoning bias hypothesis)? A substantial portion of research on the topic has been directed to test the misunderstanding hypothesis. I review this literature and argue that a stronger case can be made against the misunderstanding hypothesis. Thus, I indirectly provide support for the reasoning bias hypothesis.     

Why versus how often: Causal reasoning and the incidence of judgmental bias

When faced with the task of making a prediction or estimating a likelihood, it is argued that people often reason about the presence or absence and relative strength of possible causal mechanisms for the production of relevant outcomes. In so doing people rely on “causal cues” or properties of an inferential problem which indicate the nature of the particular causal processes which give rise to specific outcomes. It is hypothesized that causal cues, precisely because they focus attention and thought on specific causal mechanisms, can obscure the relevance of mathematical laws of probability and lead to statistically biased judgment. Two experiments were conducted. Their results support the hypothesis, showing that the incidence of the conjunction fallacy and the base rate fallacy depend on task-specific cues for causal reasoning.     

Walter the banker: the conjunction fallacy reconsidered

In a famous experiment by Tversky and Kahneman (Psychol Rev 90:293–315, 1983), featuring Linda the bank teller, the participants assign a higher probability to a conjunction of propositions than to one of the conjuncts, thereby seemingly committing a probabilistic fallacy. In this paper, we discuss a slightly different example featuring someone named Walter, who also happens to work at a bank, and argue that, in this example, it is rational to assign a higher probability to the conjunction of suitably chosen propositions than to one of the conjuncts. By pointing out the similarities between Tversky and Kahneman’s experiment and our example, we argue that the participants in the experiment may assign probabilities to the propositions in question in such a way that it is also rational for them to give the conjunction a higher probability than one of the conjuncts.     

A pattern recognition account of decision making

In the domain of pattern recognition, experiments have shown that perceivers integrate multiple sources of information in an optimal manner. In contrast, other research has been interpreted to mean that decision making is nonoptimal. As an example, Tversky and Kahneman (1983) have shown that subjects commit a conjunction fallacy because they judge it more likely that a fictitious person named Linda is a bank teller and a feminist than just a bank teller. This judgment supposedly violates probability theory, because the probability of two events can never be greater than the probability of either event alone. The present research tests the hypothesis that subjects interpret this judgment task as a pattern recognition task. If this hypothesis is correct, subjects’ judgments should be described accurately by the fuzzy logical model of perception (FLMP)—a successful model of pattern recognition. In the first experiment, the Linda task was extended to an expanded factorial design with five vocations and five avocations. The probability ratings were described well by the FLMP and described poorly by a simple probability model. The second experiment included (1) two fictitious people, Linda and Joan, as response alternatives and (2) both ratings and categorization judgments. Although the ratings were accurately described by both the FLMP and an averaging of the sources of information, the categorization judgments were described better by the FLMP. These results reveal important similarities in recognizing patterns and in decision making. Given that the FLMP is an optimal method for combining multiple sources of information, the probability judgments appear to be optimal in the same manner as pattern-recognition judgments.     

Representativeness and conjoint probability

People commonly violate a basic rule of probability, judging a conjunction of events to be more probable than at least 1 of its component events. Many manifestations of this conjunction fallacy have been ascribed to people's reliance on the representativeness heuristic for judging probability. Some conjunction fallacies, however, have been ascribed to the incorrect rules people use to combine probabilities. In 2 experiments, representativeness was pitted against probability combination to determine the contributions of each to the fallacy. Even for exemplar representativeness problems, the fallacy stemmed primarily from the application of incorrect combination rules. Representativeness seemed to be involved only insofar as it influenced the probabilities of a conjunction's component events. Implications of these findings are discussed for the representativeness account of judgmental errors and the relation between similarity and probability.     

Fallacies in probability judgments for conjunctions and disjunctions of everyday events

The conjunction fallacy occurs when people judge a conjunction B‐and‐A as more probable than a constituent B, contrary to probability theory's ‘conjunction rule’ that a conjunction cannot be more probable than either constituent. Many studies have demonstrated this fallacy in people's reasoning about various experimental materials. Gigerenzer objects that from a ‘frequentist’ standpoint probability theory is not valid for these materials, and so failure to follow the conjunction rule is not a fallacy. This paper describes three experiments showing that the conjunction fallacy occurs as consistently for conjunctions where frequentist probability theory is valid (conjunctions of everyday weather events) as for other conjunctions. These experiments also demonstrate a reliable correlation between the occurrence of the conjunction fallacy and the disjunction fallacy (which arises when a disjunction B‐or‐A is judged less probable than a constituent B). This supports a probability theory + random variation account of probabilistic reasoning. Copyright © 2008 John Wiley & Sons, Ltd.     

The conjunction fallacy?

Tversky and Kahneman (1983) showed that when subjects are asked to rate the likelihood of several alternatives, including single and joint events, they often make a "conjunction fallacy." That is, they rate the conjunction of two events as being more likely than one of the constituent events. This, they claim, is a fallacy, since the conjunction of two events can never be more probable than either of the component events. In addition, they found that prior training in probability theory does not decrease the likelihood of making this fallacy. We argue that in some contexts, an alternative that contains the conjunction of two events can be more probable than an alternative that contains only one of the conjunction's constituent events. We carried out four experiments in which we manipulated this context. The frequency of making a conjunction fallacy was affected by the manipulation of context. Furthermore, when the context was clearly specified, prior training in statistics influenced the ratings.     

More about linda or conjunctions in context

Abstract

Tversky and Kahneman (1982; 1983) reported that subjects rated the con junction of two events as more likely than one of the component events. This “conjunction effect” is an error in terms of formal probability, where the probability of more happening is always smaller than the probability of less. They explained this effect in terms of a “representativeness” heuristic. This paper focuses on the context of the problem and the suggestions implied by the questions in the task. The three studies reported here provide evidence that context effects and implicit suggestions alter subjects' judgements. Tvenky and Kahneman's models take no account of such factors. Two studies show that when implicit suggestions are reduced, subjects are much less prone to the conjunction “effect”. Subjects take being asked the question “Is person X a Y?”, as providing evidence that X may be Y.