Contextual determinants of strategic choice: Some moderators of the availability bias

Three studies explored how the influence of the ‘availability heuristic’ on frequency judgement is mediated and moderated by the perceived meaning of the task, the perceived relevance of information for the task, and the salience of differential memorability of information. All studies adapted the ‘fumous names ’paradigm (Tversky and Kahneman, 1973) in which subjects are required to listen to a list of names of known personalities of both sexes and then judge the frequency of men and women. The availability heuristic (Tversky and Kahneman, 1973) posits that classes whose instances are easy to imagine or recall will be perceived as relatively frequent, so that when names of one sex are more famous and thus memorable this category will be rated as more numerous even when it occurs less frequently. Consistent with the notion that the use of availability is sensitive to task interpretation, we showed that the availability effect is eliminated over successive trials (Study 1) and moderated when task instructions render different categories salient (Study 2). In the third study it is shown that conditions which facilitate awareness of the biasing relationship between gender and fame (memorability), decrease the use of the availability heuristic by moderating frequency estimates of the more famous category. Results of these studies emphasize the context-bound and strategic aspects of judgement.     

Judgments relative to patterns: how temporal sequence patterns affect judgments and memory

Six experiments studied relative frequency judgment and recall of sequentially presented items drawn from 2 distinct categories (i.e., city and animal). The experiments show that judged frequencies of categories of sequentially encountered stimuli are affected by certain properties of the sequence configuration. We found (a) a first-run effect whereby people overestimated the frequency of a given category when that category was the first repeated category to occur in the sequence and (b) a dissociation between judgments and recall; respondents may judge 1 event more likely than the other and yet recall more instances of the latter. Specifically, the distribution of recalled items does not correspond to the frequency estimates for the event categories, indicating that participants do not make frequency judgments by sampling their memory for individual items as implied by other accounts such as the availability heuristic (Tversky & Kahneman, 1973) and the availability process model (Hastie & Park, 1986). We interpret these findings as reflecting the operation of a judgment heuristic sensitive to sequential patterns and offer an account for the relationship between memory and judged frequencies of sequentially encountered stimuli.     

The availability heuristic with famous names: a replication

In two experiments, 195 Canadian undergraduates initially judged a list of 25 names (12 famous men and 13 nonfamous women or 12 famous women and 13 nonfamous men) for familiarity. Contrary to previous research, subsequent estimates of the perceived number of men's and women's names were not higher when the names were famous than nonfamous. When the estimated differences were compared to the true difference (-1), famous names were judged more numerous than nonfamous names, but the size of the effect (d = 0.34) was smaller than in previous research. Reasons for these findings are discussed.     

The effect of category focus at encoding on category frequency estimation strategies

We investigated whether category focus at encoding affects how people estimate category frequencies. Participants in three experiments viewed items of various categories. They estimated category frequencies after categorizing them into relevant versus irrelevant categories (Experiments 1-2) or after categorizing versus memorizing them (Experiment 3). Verbal protocols (Experiments 2A and 2B), response latencies (Experiments 2A and 2B), frequency estimate changes (Experiment 2B), and the relationships between objective and estimated category frequencies and instance recall (Experiments 1-3) showed that the participants mainly used availability to estimate category frequencies after memorizing instances (Experiment 3) or after categorizing them into irrelevant categories (Experiments 1-2). After categorizing items into relevant categories, the participants relied more often on stored category frequency information (Experiments 1-3).     

The Hindsight Bias: The Role of the Availability Heuristic and Perceived Risk

The influence of outcome knowledge (Fischhoff, 1975) and the availability heuristic (Tversky & Kahneman, 1974) on judgments of perceived risk was explored here. This study found that subjects were capable of making relatively appropriate probability estimates for disease, accident, and homicide in foresight, but they made relatively biased estimated in hindsight. The results suggest that hindsight information activates the use of the availability heuristic on peoples' probability estimates of certain misfortune.     

Probability and category redefinition in the fault tree paradigm

Fault trees have been advocated as aids for problem solvers. However, research has suggested limitations in their usefulness. Fischhoff, Slovic, and Lichtenstein (1978) found that subjects given incomplete (pruned) trees were insensitive to omissions; these authors hypothesized that Tversky and Kahneman's (1974) availability heuristic was the mediating factor. Using a within-subjects design, subjects in Experiment 1 received both full and pruned trees and estimated probabilities for various reasons why a car would fail to start. To increase the availability of omissions, some Experiment 1 subjects first generated possible causes of starting failure. The basic Fischhoff et al. findings were replicated, but several aspects of the results argued against the availability hypothesis as the mechanism for judgment. Instead, subjects appeared to idiosyncratically redefine category membership when making judgments based upon pruned trees. By employing a sorting task in Experiment 2 we corroborated the results of Experiment 1: Subjects do redefine the actual contents of the categories when faced with an omission from the fault tree. The implications of these results for the use of fault trees as a problem solving aid are discussed.     

The illusion of fame: how the nonfamous become famous

This article reports 2 experiments in which nonfamous faces were paired with famous (e.g., Oprah Winfrey) or semifamous (e.g., Annika Sorenstam) faces during an initial orienting task. In Experiment 1, the orienting task directed participants to consider the relationship between the paired faces. In Experiment 2, participants considered distinctive qualities of the paired faces. Participants then judged the fame level of old and new nonfamous faces, semifamous faces, and famous faces. Pairing a nonfamous face with a famous face resulted in a higher fame rating than pairing a nonfamous face with a semifamous face. The fame attached to the famous people was misattributed to their nonfamous partners. We discuss this pattern of results in the context of current theoretical explanations of familiarity misattributions.     

Psychological Processes Underlying Cultivation Effects Further Tests of Construct Accessibility

This study tested whether the accessibility of information in memory mediates the cultivation effect (i.e., the effect of television viewing on social perceptions), consistent with the availability heuristic (Tversky & Kahneman, 1973). Accessibility was operationalized as the time needed to generate frequency estimates of the real-world prevalence of crime, marital discord, and particular occupations. The independent variable was amount of soap opera viewing, and the study used only very heavy (5 or more hours per week) and very light (zero hours per week) viewers. Heavy viewers gave significantly higher frequency estimates (cultivation effect) and responded significantly faster (accessibility effect) than did light viewers, replicating the findings of Shrum and O'Gunn (1993). Soap opera viewing also had an indirect effect on the frequency estimates of crime and occupational prevalence through its effect on response latency, supporting the notion of accessibility as a mediating variable. No such mediating effect was noted for marital discord estimates.     

Influence of prior events on cognitive judgments in amnesia.

Amnesic patients and control Ss read the names of famous and nonfamous persons. Subsequently, both groups were more likely to designate a name as famous if it had been encountered previously. The facilitatory effect of prior presentation was similar for amnesic patients and control Ss and similar for famous and nonfamous names. For amnesic patients, the effect occurred despite severely impaired recognition memory for the names. In a 2nd experiment, recombining the first and last names that had been presented together did not diminish the facilitatory effect of prior presentation, which indicates that the effect does not depend on forming an association between first and last names. The results show that nondeclarative (implicit) memory can support the acquisition of information that is specific (e.g., names of persons) and that has no preexisting representation (e.g., nonfamous names).     

Overconfidence in estimation: Testing the anchoring-and-adjustment hypothesis

People are frequently overconfident in the accuracy of their estimates of uncertain quantities. The present study requested 50%- or 90%-confidence ranges. Overconfidence is shown when less than the target percentage of ranges include the true value. Tversky and Kahneman (1974) proposed that people use an anchoring-and-adjustment heuristic: They begin with a starting value, one supplied to them or generated by them, and insufficiently adjust their estimates around this anchor. The present data support the proposed anchoring process. If subjects receive another person's point estimates, their own implicit point estimates are correlated with these values. However, anchoring- and-adjustment processes do not invariably produce overconfidence. Subjects who receive anchors are no more overconfident than are those who do not receive anchors. If subjects are required to produce a point estimate first, overconfidence decreases; processes involved in explicitly displaying the point estimate are implicated. Overconfidence may occur because people do not realistically assess their estimation ability.     

Declarativeand nondeclarativememory in opposition:When priorevents influence amnesicpatients morethan normal subjects

Amnesic patients and normal subjects read the names of nonfamous persons. Then, after being told that all the names were nonfamous, subjects judged the fame of names on a mixed list of new famous names, old nonfamous names, and new nonfamous names. Finally, they took a recognition memory test involving old and new nonfamous names. In this way, declarative (explicit) memory and nondeclarative (implicit) memory were placed in opposition. That is, recollection that a name had been recently presented (and was therefore nonfamous) opposed the focilitatory effect by which prior presentation ordinarily increases the tendency to judge that name as famous. Normal subjects exhibited good recognition memory and no fame-judgment effect—that is, no difference in fame judgments for new and old nonfamous names. By contrast, for the amnesic patients recognition memory was poor, but astrong fame-judgment effect occurred—that is, amnesic patients judged old nonfamousnames as famous. The results provide additional evidence that the fame-judgment effect is supported fully by nondeclarative (implicit) memory and is independent of the limbic/diencephalicbrain structures damaged in amnesia.     

Availability and category-frequency estimation

Individuals judged how often examples of taxonomic categories had occurred in a study list. An availability hypothesis was tested--that frequency estimates are based on the retrieval of instances. Cued (by category names) recall of the examples served as an index of availability. The hypothesis was confirmed--there were strong positive correlations between frequency judgments and recall (with the influence of actual frequency removed)--given one or more of the following conditions: List instances were not categorized aloud as they were presented; frequency estimation was preceded by cued recall; frequency estimation was delayed by a week. Limitations on availability occurred under other conditions--notably, when individuals, during list presentation, named the categories to which items belonged and received feedback about their categorizations. Under these circumstances, correlations of frequency estimation and recall were often not significantly different from zero, and frequency judgments and recall sometimes reacted differently to changes in independent variables (e.g., frequency judgments of young and elderly subjects did not differ reliably, even though cued recall of young persons markedly exceeded that of elderly subjects).     

贝叶斯推理研究综述

Kahneman 和Tversky在70年代初期发现人们在概率推理中并不遵循数学上的贝叶斯定理,常常由于忽略问题中的基础概率而对稀少事件的条件概率作出夸大的反应。此后心理学家采用文本范式和经验范式对此问题进行了大量的研究,并涌现了一些不同的理论观点,主要有启发法策略论(代表性启发法和可得性启发法)、自然抽样空间假说、频率效应论和抽样加工理论。     

Insight into the law of large numbers: A comparison of piagetian and judgement theory

Subjects were tested for their understanding of the law of large numbers in three ways: by means of a Piagetian task involving the distribution of balls between two compartments, by means of written tasks similar to those devised by Kahneman and Tversky (1972), and by means of a task involving comparisons of samples of counters drawn from a larger population. For the sample comparison task, subjects relied heavily on proportional information-ignoring sample size, thereby supporting the conclusions of Kahneman and Tversky (1972). However with regard to the other two tasks an order effect was found: subjects did significantly better with the Kahneman and Tversky tasks if they had first been tested on a Piagetian task. In Experiment II, the order effect was replicated, indicating that subjects may have a narrow insight into the law of large numbers which is not recruited in appropriate contexts unless primed by the task environment.     

Category effects on stimulus estimation: Shifting and skewed frequency distributions

The category adjustment model (CAM) proposes that estimates of inexactly remembered stimuli are adjusted toward the central value of the category of which the stimuli are members. Adjusting estimates toward the average value of all category instances, properly weighted for memory uncertainty, maximizes the average accuracy of estimates. Thus far, the CAM has been tested only with symmetrical category distributions in which the central stimulus value is also the mean. We report two experiments using asymmetric (skewed) distributions in which there is more than one possible central value: one where the frequency distribution shifts over the course of time, and the other where the frequency distribution is skewed. In both cases, we find that people adjust estimates toward the category’s running mean, which is consistent with the CAM but not with alternative explanations for the adjustment of stimuli toward a category’s central value.     

A foundation for support theory based on a non-Boolean event space

A new foundation is presented for the theory of subjective judgments of probability known in the psychological literature as “Support Theory”. It is based on new complementation operations that, unlike those of classical probability theory (set-theoretic complementation) and classical logic (negation), need not satisfy the principles of the Law of The Excluded Middle and the Law of Double Complementation. Interrelationships between the new complementation operations and the Kahneman and Tversky judgmental heuristic of availability are described.     

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     

Event-related potentials indicate different processes to mediate categorical and associative priming in person recognition

Whether representations of people are stored in associative networks based on co-occurrence or are stored in terms of more abstract semantic categories is a controversial question. In the present study, participants performed fame decisions to unfamiliar or famous target faces (Experiment 1) or names (Experiment 2), which were primed, either by highly associated celebrity names or by names from the same occupational category, or were unprimed. Reaction times and event-related potentials (ERPs) were recorded. Reaction times yielded significant priming effects for both associated and same category conditions. ERPs to targets in the associated condition were significantly more positive than were ERPs in all other conditions over central and parietal areas (300-600 ms; N400 priming effect). By contrast, a more posterior effect was found for categorical priming. These findings held for both cross-domain (Experiment 1) and within-domain conditions (Experiment 2). Results (a) demonstrate behavioral and ERP evidence for categorical priming in person recognition, consistent with the assumption that shared semantic information units can mediate semantic priming, and (b) suggest that associative and categorical priming are based on mechanisms that are at least partially different.     

Knowledge does not necessarily make the heart grow fonder: The moderating role of knowledge on accessibility experiences

Accessibility experiences have been a subject of interest since Tversky and Kahneman (1973) published their account of the availability heuristic—specifically, individuals often utilize the phenomenological experience of ease or difficulty of recall in constructing a judgment (Schwarz, 1998). The reported studies contribute further to work in this area by examining the moderating role of knowledge on accessibility experiences and their use in evaluative judgments. We argue that knowledgeable individuals are more likely to experience interference effects in early stages of recall. This would result in a reversal of the usual phenomenon such that while low knowledge individuals would find recalling larger sets effortful, which would lead them to form more negative evaluations when recalling larger amounts of information, high knowledge individuals would find recalling smaller sets effortful and would form more negative evaluations when recalling smaller amounts of information. We discuss potential explanations and draw attention to the distinction between generating a response and the appropriateness of the response in accessibility experiences.