Ilan Yaniv

Individual and Group Behavior in the Ultimatum Game: Are Groups More “Rational” Players?

This article reports two experiments that compared the standard ultimatum game played by individuals with the same game played by three-person groups. In the group treatment, the members of the allocating group conducted a brief, face-to-face discussion in order to decide, as a group, on a proposed division, whereas the members of recipient group held a discussion on whether to accept or reject the proposal. If the proposal was accepted, each group member received an equal share of his groups payoff (the pie in the group condition was three times that in the individual condition). In both experiments, groups offered less than individuals. But as indicated by the low rejection rate in both treatments, groups were also willing to accept less.

Precision and Accuracy of Judgmental Estimation

Whereas probabilistic calibration has been a central normative concept of accuracy in previous research on interval estimates, we suggest here that normative approaches for the evaluation of judgmental estimates should consider the communicative interaction between the individuals who produce the judgments and those who receive or use them for making decisions. We analyze precision and error in judgment and consider the role of the accuracy‐informativeness trade-oA (Yaniv and Foster, 1995) in the communication of estimates. The results shed light on puzzling findings reported earlier in the literature concerning the calibration of subjective confidence intervals. * c 1997 by John Wiley & Sons, Ltd.

Elimination and inclusion procedures in judgment.

Consider two judgment procedures for selecting an answer from a set of multiple alternatives. One could answer a question either by including likely alternatives from the initial set of alternatives or by eliminating the least likely alternatives from that same initial set. An interesting question is whether the two judgment processes are equivalent and yield the same final selection. The results from two studies indicate that individuals generate significantly larger sets of candidates in an elimination process than in an inclusion process, with concurrent increase in accuracy. We show that this finding is a logical consequence of the noncomplementarity of elimination and inclusion, and suggest a screening model with two criteria to explain the results. #1997 by John Wiley & Sons, Ltd.

Spurious Consensus and Opinion Revision: Why Might People Be More Confident in Their Less Accurate Judgments?.

In the interest of improving their decision making, individuals revise their opinions on the basis of samples of opinions obtained from others. However, such a revision process may lead decision makers to experience greater confidence in their less accurate judgments. The authors theorize that people tend to underestimate the informative value of independently drawn opinions, if these appear to conflict with one another, yet place some confidence even in the spurious consensus, which may arise when opinions are sampled interdependently. The experimental task involved peoples revision of their opinions (caloric estimates of foods) on the basis of advice. The method of sampling the advisory opinions (independent or interdependent) was the main factor. The results reveal a dissociation between confidence and accuracy. A theoretical underlying mechanism is suggested whereby people attend to consensus (consistency) cues at the expense of information on interdependence. Implications for belief updating and for individual and group decisions are discussed.

Inclusive and exclusive modes of thinking: Studies of prediction, preference, and social perception during parliamentary elections

Abstract The 1999 Israeli multi-party parliamentary election was used for studying the effects of inclusive and exclusive modes of thinking. In three experiments, we tested a theoretical framework whose major elements are the justification process, a distinction between middling and clearcut options, and the use of inclusion and exclusion threshold criteria. In Studies 1–2, respondents were asked to predict either of which parties would win seats in the parliament (inclusion) or which parties would fail to win seats in the parliament (exclusion). In Study 2, respondents were also asked to use inclusive or exclusive modes to indicate their preferences and in Study 3, they were asked to make either inclusive or exclusive judgments about the platforms of two extreme political parties. We found consistent discrepancies between the outcomes of inclusion and exclusion processes, such that choice sets generated in exclusion were larger than those generated in inclusion. A second major finding was the option effect, namely, the discrepancies between the two modes of thinking were larger for middling than for clearcut options. The third main finding was an expertise effect: the less knowledgeable respondents exhibited greater discrepancies than did the more knowledgeable ones. Our theoretical framework accounts for the inclusion–exclusion discrepancy, the option effect, and the expertise effect. We discuss the implications of these findings for judgment and choice in social settings and also for the understanding of question-form effects in opinion surveys—in particular, the allow–forbid effect.

On not wanting to know and not wanting to inform others: choices regarding predictive genetic testing

Recent advancement in genetics testing for late-onset diseases raises fundamental decision dilemmas. The first study surveyed people’s willingness to undergo predictive testing to find out about their own predisposition for certain incurable, late-onset diseases. The second study investigated the respondents’ willingness to be tested as a function of the base rate of the disease, test diagnosticity, and the availability of treatment for the disease. In addition we surveyed (in the first study) people’s willingness to disclose to others personal information about their genetic predisposition. The findings show that people often prefer not to know, as if they are choosing “protective ignorance”. Respondents’ verbal justifications of their choices were also analyzed. Respondents offered emotional, cognitive-instrumental, and strategic reasons for their preferences. The findings are compared with other issues in behavioral decision theory, including attitudes towards uncertainty and desire for control. The implications of the findings for policies and legislation on genetic tests are also considered.

Decision Framing and Support for Concessions in the Israeli–Palestinian Conflict

The purpose of the study is to explore, in the context of the Israeli-Palestinian conflict, the influence of framing a decision task as inclusion or exclusion on Israeli Jewish respondents’ support for the concession of Jewish settlements in the West Bank and Gaza. Respondents received a list of 40 Jewish settlements. Details such as the number of residents and geographical location were provided for each settlement. The respondents were randomly assigned to one of two conditions. In the inclusion condition, 55 respondents were asked to mark the settlements for which they recommended that Israeli sovereignty be conceded. In the exclusion condition, 53 respondents were asked to mark the settlements for which they recommended that Israeli sovereignty not be conceded. The findings confirm the predictions tested and indicate that: (1) Framing the task in terms of inclusion or exclusion affects respondents’ support for territorial compromise, so that respondents in the exclusion condition support the concession of more settlements than respondents in the inclusion condition. (2) Framing the task in terms of inclusion or exclusion has a greater effect on support for conceding options (settlements) that are perceived as ambiguous (less consensual in the climate of opinion) in comparison to options (settlements) that are perceived as more clearcut (more consensual). The theoretical and practical implications of these findings are discussed.

The Wisdom of Crowds in Matters of Taste

Decision makers can often improve the accuracy of their judgments on factual matters by consulting “crowds” of others for their respective opinions. In this article, we investigate whether decision makers could similarly draw on crowds to improve the accuracy of their judgments about their own tastes and hedonic experiences. We present a theoretical model that states that accuracy gains from consulting a crowd’s judgments of taste depend on the interplay among taste discrimination, crowd diversity, and the similarity between the crowd’s preferences and those of the decision maker. The model also delineates the boundary conditions for such “crowd wisdom.” Evidence supporting our hypotheses was found in two laboratory studies in which decision makers made judgments about their own enjoyment of musical pieces and short films. Our findings suggest that although different people may have different preferences and inclinations, their judgments of taste can benefit from the wisdom of crowds. Data are available a...

False Negotiations The Art and Science of Not Reaching an Agreement

The usual purpose of negotiations is to explore options and reach an agreement, if possible. We investigated a notable exception to this generalization, where a party negotiates without any intention of reaching an agreement. False negotiation occurs when a party gains more by stalling the negotiations until an external change takes place that improves its position considerably. While false negotiators aim to avoid agreement within the current frame of the negotiations, they also aim to keep the negotiation process alive, since walking away from the negotiation table could endanger their position. We report the results of a study that compared the actions of false and sincere negotiators. The false negotiators used competitive tactics that encumbered the negotiations, yet they concealed their intentions by maintaining a facade of cooperation. Our theoretical discussion is focused on the balancing act involved in false negotiations and the challenges it poses for actors in social, managerial, and political settings. We conclude our analysis with an example from the realm of international negotiations.

Inferring Accuracy for Judges and Items: Choice of Unit of Analysis Reverses the Conclusions

This study explores the relationship between the precision and the accuracy of forecasts using either judge or item as the unit of analysis. Participants in five experiments answered general-knowledge questions by indicating intervals that were likely to include the correct answer. Results indicate that the precision of an interval estimate is not a straightforward cue to the likelihood that such an interval includes the truth (hit rate). Whereas judges who state more precise estimates (i.e. who provide narrower interval estimates) have lower hit rates, questions for which the average judgment is more precise have higher hit rates. Thus, the relation between precision and accuracy depends on whether one ‘slices’ the data by judge or by question. We offer an explanation for this seemingly paradoxical effect and implement it as a computer simulation to demonstrate its validity.