Based on undergraduates' self-reports of mate preferences for various traits and self-perceptions of their own levels on those traits, Buston and Emlen [Buston PM, Emlen ST (2003) Proc Natl Acad Sci USA 100:8805-8810] concluded that modern human mate choices do not reflect predictions of tradeoffs from evolutionary theory but instead follow a ''likes-attract'' pattern, where people choose mates who match their self-perceptions. However, reported preferences need not correspond to actual mate choices, which are more relevant from an evolutionary perspective. In a study of 46 adults participating in a speed-dating event, we were largely able to replicate Buston and Emlen's self-report results in a pre-event questionnaire, but we found that the stated preferences did not predict actual choices made during the speed-dates. Instead, men chose women based on their physical attractiveness, whereas women, who were generally much more discriminating than men, chose men whose overall desirability as a mate matched the women's self-perceived physical attractiveness. Unlike the cognitive processes that Buston and Emlen inferred from selfreports, this pattern of results from actual mate choices is very much in line with the evolutionary predictions of parental investment theory.assortative mating ͉ decision making ͉ evolutionary psychology ͉ sexual selection ͉ speed-dating W hat characteristics are preferable in a human mate? The answer depends, as ever in behavioral research, on how one asks the question. When asked in a normative mannerwhat characteristics should men and women seek in a mate?-the question can be addressed from the theoretical framework of evolutionary biology. Starting with the assumption that the underlying function of mate choice is reproductive success, evolutionary psychologists have proposed that men should seek young, fertile, faithful women, and women should seek highstatus, resourceful, committed men, and both sexes should bargain for the traits they desire in the other sex by offering the desirable traits that they themselves possess (1, 2). When people are asked what traits they prefer in a mate, however, the answer to this question becomes less clear. On the one hand, the traits that people around the world say they prefer match the evolutionary predictions for making adaptive mate choices (3-5). On the other hand, Buston and Emlen (6) found that people do not indicate that they want to exchange, for instance, male status for female attractiveness (a hypothesis, based on an evolutionary mating market framework, that they call ''potentials-attract'') but rather seek someone just as high-status (or low) and attractive (or not) as themselves (a form of active positive assortative mating they call ''likes-attract''). Why do the theoretical mate choice predictions and stated mate preferences clash in this way? In this work, by comparing the attributes that a group of mate-seeking individuals said they prefer in a mate with what they actually chose in potential partners, we show how the conflicting re...

The weather forecast says that there is a "30% chance of rain," and we think we understand what it means. This quantitative statement is assumed to be unambiguous and to convey more information than does a qualitative statement like "It might rain tomorrow." Because the forecast is expressed as a single-event probability, however, it does not specify the class of events it refers to. Therefore, even numerical probabilities can be interpreted by members of the public in multiple, mutually contradictory ways. To find out whether the same statement about rain probability evokes various interpretations, we randomly surveyed pedestrians in five metropolises located in countries that have had different degrees of exposure to probabilistic forecasts--Amsterdam, Athens, Berlin, Milan, and New York. They were asked what a "30% chance of rain tomorrow" means both in a multiple-choice and a free-response format. Only in New York did a majority of them supply the standard meteorological interpretation, namely, that when the weather conditions are like today, in 3 out of 10 cases there will be (at least a trace of) rain the next day. In each of the European cities, this alternative was judged as the least appropriate. The preferred interpretation in Europe was that it will rain tomorrow "30% of the time," followed by "in 30% of the area." To improve risk communication with the public, experts need to specify the reference class, that is, the class of events to which a single-event probability refers.

In the age of the Internet and easy access to almost infinite information, the problem of information overload among consumers is bound to become of great importance to marketers. By means of simulations we show that this 'tyranny of choice' is avoidable. Consumers can neglect most product information and yet make good choices, so long as either there is no conflict among the product attributes or the attributes are unequally important. In these conditions, only one attribute is enough to select a good option -one within ten percent of the highest value possible. We conclude with marketing implications of these findings. Key Words • choice • choice tyranny • consumer choice • fast and frugal heuristics • information overload • internet shopping • multi-criteria decision making • too much choice • preference Choice is a double-edged sword. On one side we are inherently attracted to choice and are utterly disappointed when we have too little of it. For example, Bown et al. (2003) showed that an option is more often chosen when it is offered jointly with another option than when it is offered alone. In the same spirit, consumer researchers have long documented consumers' attraction to variety. For instance, Iyengar and Lepper (2000) showed that more consumers stopped to taste a jam from a stand with a large selection of 24 varieties than from a stand with a small selection of six jams. On the other hand, more choice is not always a good thing. Choosing from overly large sets makes consumers feel that the decision is difficult 13 Volume 7(1): 13-26

Two studies examine the effect of the complexity of the choice environment on the perceived duration of the time spent choosing. The experiments demonstrate that the estimation of the time spent making a decision is affected by the number of options available in the choice set. In Experiment 1, participants having to choose 1 of 24 mobile phones tended to underestimate the time spent whereas participants confronted with the choice of 6 mobile phones tended to overestimate the actual time spent. Experiment 2 corroborates this finding, in the presence of varying degrees of attribute correlation. We conclude with theoretical and practical implications for marketers.

Multi-criteria decision analysis (MCDA) involves asking decision makers difficult questions, and can leave them thinking that their judgements are not as coherent as they might have thought. This experience can be distressing and may even lead to rejection of the analysis. The psychology of preference sheds light both on how people naturally make choices without decision analytic assistance, and on how people think about the MCDA elicitation questions. As such, it can help the analyst to respond helpfully to difficulties which decision makers may face. In this paper, we review research from Behavioural Decision Theory relevant to MCDA. Our review follows the MCDA process, discussing research relevant to the structuring, value elicitation, and weighting phases of the analysis, outlining relevant and important findings, and open questions for research and practice.

This review is about decision technology-the rules and tools that help us make wiser decisions. First, we review the three rules that are at the heart of most traditional decision technology-multi-attribute utility, Bayes' theorem, and subjective expected utility maximization. Since the inception of decision research, these rules have prescribed how we should infer values and probabilities and how we should combine them to make better decisions. We suggest how to make best use of all three rules in a comprehensive 19-step model. The remainder of the review explores recently developed tools of decision technology. It examines the characteristics and problems of decision-facilitating sites on the World Wide Web. Such sites now provide anyone who can use a personal computer with access to very sophisticated decision-aiding tools structured mainly to facilitate consumer decision making. It seems likely that the Web will be the mode by means of which decision tools will be distributed to lay users. But methods for doing such apparently simple things as winnowing 3000 options down to a more reasonable number, like 10, contain traps for unwary decision technologists. The review briefly examines Bayes nets and influence diagrams-judgment and decision-making tools that are available as computer programs. It very briefly summarizes the state of the art of eliciting probabilities from experts. It concludes that decision tools will be as important in the 21st century as spreadsheets were in the 20th.

We examine heterogeneity in COVID-19 vaccine hesitancy across eight European countries. We reveal striking differences across countries, ranging from 6.4% of adults in Spain to 61.8% in Bulgaria reporting being hesitant. We experimentally assess the effectiveness of different messages designed to reduce COVID-19 vaccine hesitancy. Receiving messages emphasizing either the medical benefits or the hedonistic benefits of vaccination significantly increases COVID-19 vaccination willingness in Germany, whereas highlighting privileges contingent on holding a vaccination certificate increases vaccination willingness in both Germany and the United Kingdom. No message has significant positive effects in any other country. Machine learning–based heterogeneity analyses reveal that treatment effects are smaller or even negative in settings marked by high conspiracy beliefs and low health literacy. In contrast, trust in government increases treatment effects in some groups. The heterogeneity in vaccine hesitancy and responses to different messages suggests that health authorities should avoid one-size-fits-all vaccination campaigns.

Consumer research has shown the downsides of offering consumers too much choice and is now starting to explore moderators of the effect of assortment size on consumer decisions. Building on previous studies, this research examines two side effects of tyranny of choice in the marketplace: high assortment entropy and high density of attribute values. We analyze two supermarkets-one offering small, the other large assortments-to examine how size, entropy, and density relate in the marketplace. We find that larger supermarket assortments come with higher density and higher entropy. Simulations of various choice strategies in these marketplace assortments reveal that making selections from large high-density and high-entropy