The Natural Selection of Prediction Heuristics: Anchoring and Adjustment versus Representativeness

There are several heuristics which people use in making numerical predictions and these heuristics compete for the determination of prediction output. Some of them (e.g. representativeness) lead to excessively extreme predictions while others (e.g. anchoring and adjustment) lead to regressive (and even over-regressive) predictions. In this paper we study the competition between these two heuristics by varying the representation of predictor and outcome. The results indicate that factors which facilitate reliance on representativeness (e.g. compatibility between predictor and outcome) indeed lead to an increase in extremity, while factors that facilitate reliance on anchoring and adjustment (e.g. increased salience of a potential anchor) lead to a decrease in extremity.     

The UK Hybrid Embryo Controversy: Delegitimising Counterpublics

The UK Human Fertilisation and Embryology Act of 1990 was revised in 2008 in response to legal challenges, societal changes and clinical advances since 1990. A provision permitting the creation of animal–human hybrid embryos was the subject of an extremely effective public relations (PR) campaign by embryo scientists and other supporters of such experimentation. In response, science correspondents of the ‘serious’ or ‘quality’ press commented favourably on these PR activities; this validation supplemented key messages in their press releases. The approval conferred on attempts to shape public opinion was explicitly contrasted with the public consultation exercise conducted by the UK Department of Health in 2005. Press coverage of the campaign demonstrated asymmetrical framings of the representativeness of public opinion and scientists' accounts of their proposed research. Scientists' views were represented as objective and therefore a legitimate basis for policymaking, in contrast with subjective views of putatively uninformed or opposed publics. Such opponents were cast as a counterpublic. The public interest was limited to evaluating the science on its own terms, thus pre-empting consideration of the possibility that public interests and scientists' interests may not coincide.     

The test taker's fallacy: How students guess answers on multiple‐choice tests

Many students and applicants take multiple‐choice tests to demonstrate their competence and achievement. When they are unsure, they guess the most likely answer to maximize their score. Despite the impact of guessing on test reliability and individual performance, studies have not examined how patterns of answer sequences in multiple‐choice tests affect guessing. This research presents the test taker's fallacy, which refers to an individual's tendency to expect a different answer to appear for the next question given a run of the same answer choices. The test taker's fallacy exhibits negative recency, similar to the gambler's fallacy. However, extending the sequential judgment literature, the test taker's fallacy shows that negative recency arises even when sequences may or may not be randomly generated. In three studies, including a survey and experiments, the test taker's fallacy is robustly observed. The test taker's fallacy is consistent with the operation of the representativeness heuristic. This research explains what and how test takers guess given a streak of answers and extends judgment under uncertainty to the test‐taking context.     

Emotional reactions to scandals: When does moral character make a difference?

A scandal can evoke public outrage when it is widely publicized and involves an individual who is perceived to have a high level of cultural representativeness. Two experiments showed that when the scandalous target's moral character was highlighted, emotional responses towards the target were least negative when the scandal was widely circulated and when the target was seen as a representative of his culture. These results suggest that when a cultural symbol is implicated in a widely‐circulated scandal, the negative emotions directed towards the scandalous individual can be alleviated when the public remains confident in his or her commitment to morality.     

Intuitive prediction: ecological validity versus representativeness

Insufficiently regressive intuitive predictions have been attributed to mistaken reliance on the representativeness heuristic. In contrast, we suggest that intuitive predictions stem from a conceptualization of ‘goodness of prediction’ that differs from the accepted statistical definition in terms of error minimization, namely, ecological validity—that is, representation of the substantive characteristics of the predicted variable Y and its distribution as well as of the relationship between Y and the predictor X—rather than minimization of prediction errors. Simultaneous satisfaction of the above representation requirements is achieved by multivalued prediction: The prediction of different Y′ values for the same X value, resulting in conditional distributions Y′|X for at least some X values. Empirical results supporting this hypothesis are presented and discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Exploring the conjunction fallacy within a category learning framework

The literature presents two major theories on the cause of the conjunction fallacy. The first attributes the conjunction fallacy to the representativeness heuristic. The second suggests that the conjunction fallacy is caused by people combining p(A) and p(B) into p(A&B) in an inappropriate manner. These two theories were contrasted in two category‐learning experiments. As predicted by the latter theory, data showed that participants that could assess p(A&B) directly made fewer conjunction fallacies than participants who had to compute p(A) and p(B) separately and then combine them into p(A&B). Least conjunction fallacies were observed in the cases where the representativeness heuristic was applicable. Overall, data showed that an inability to appropriately combine probabilities is one of the key cognitive mechanisms behind the conjunction fallacy. Copyright © 2008 John Wiley & Sons, Ltd.     

The alternative explanation to the alternative‐outcome effect and the detection of the focal outcome effect

Abstract: Previous studies on subjective probability judgment indicate that pair‐wise comparison between the focal and the strongest alternative outcome plays an important role in probability judgment. This study, however, found that the randomness of alternative outcomes affected probability judgment for focal outcome. In the present study, 182 participants provided probability estimates for winning on hypothetical slot machines where both successes and losses were composed of multiple outcomes. The randomness of both the focal and alternative outcomes were defined by the expression used in Rappoport and Budescu (1997 ). The analysis indicated that the more random the distributions of both focal and alternative outcomes, the higher the estimated probability for focal outcome. Some theoretical suggestions are discussed.     

测验链接中的锚题代表性研究

本文旨在以“锚题代表性”这一研究命题切入,探索在非等组锚测验设计下,作为实现测验链接的重要载体,锚题和相关的测验试卷/水平之间究竟应该有什么关系。本文首先指出锚题代表性这一概念在等值和垂直量尺化领域中具有不同的含义,并给出其在垂直量尺化中的含义。通过考察测验链接中有关锚题代表性的既有研究,系统总结相关研究成果,本文概括出了当前锚题构建实践的可能优化方案,分析了锚题代表性研究的未来方向。     

Exemplars in the mist: the cognitive substrate of the representativeness heuristic

The idea that people often make probability judgments by a heuristic short-cut, the representativeness heuristic, has been widely influential, but also criticized for being vague. The empirical trademark of the heuristic is characteristic deviations between normative probabilities and judgments (e.g., the conjunction fallacy, base-rate neglect). In this article the authors contrast two hypotheses concerning the cognitive substrate of the representativeness heuristic, the prototype hypothesis (Kahneman & Frederick, 2002) and the exemplar hypothesis (Juslin & Persson, 2002), in a task especially designed to elicit representativeness effects. Computational modelling and an experiment reveal that representativeness effects are evident early in training and persist longer in a more complex task environment and that the data are best accounted for by a model implementing the exemplar hypothesis.     

Trading performance,disposition effect,overconfidence, representativeness bias,and experience of emerging market investors

Using brokerage account data from China, we study investment decision making in an emerging market. We find that Chinese investors make poor trading decisions: the stocks they purchase underperform those they sell. We also find that Chinese investors suffer from three behavioral biases: (i) they tend to sell stocks that have appreciated in price, but not those that have depreciated in price, consistent with a disposition effect, acknowledging gains but not losses; (ii) they seem overconfident; and (iii) they appear to believe that past returns are indicative of future returns (a representativeness bias). In comparisons to prior findings, Chinese investors seem more overconfident than U.S. investors (i.e., the Chinese hold fewer stocks, yet trade very often) and their disposition effect appears stronger. Finally, we categorize Chinese investors based on proxy measures of experience and find that “experienced” investors are not always less prone to behavioral biases than are “inexperienced” ones. Copyright © 2007 John Wiley & Sons, Ltd.