How Endogenous Crowd Formation Undermines the Wisdom of the Crowd in Online Ratings.

People frequently consult average ratings on online recommendation platforms before making consumption decisions. Research on the wisdom-of-the-crowd phenomenon suggests that average ratings provide unbiased quality estimates. Yet we argue that the process by which average ratings are updated creates a systematic bias. In analyses of more than 80 million online ratings, we found that items with high average ratings tend to attract more additional ratings than items with low average ratings. We call this asymmetry in how average ratings are updated endogenous crowd formation. Using computer simulations, we showed that it implies the emergence of a negative bias in average ratings. This bias affects items with few ratings particularly strongly, which leads to ranking mistakes. The average-rating rankings of items with few ratings are worse than their quality rankings. We found evidence for the predicted pattern of biases in an experiment and in analyses of large online-rating data sets.

The dynamics of choice in a changing world: Effects of full and partial feedback.

We explored the dynamics of choice behavior while the values of the options changed, unannounced, several times. In particular, choice dynamics were compared when the outcome values of all available options were known (full feedback) and when the outcome value of only the chosen option was known (partial feedback). The frequency of change, the values of the options, and the difference between them were also manipulated. In an experiment with N = 427, we found that the patterns of choices were different for the two levels of feedback. Whereas behavior in the full-feedback condition showed a tendency to switch choices following a missed opportunity-replicating previous findings-the behavior in the partial-feedback condition was different. It was sensitive to the outcome value of the chosen option in comparison to some memory of the last-experienced outcome value of the unchosen option. However, the comparison of these two values influenced choice behavior only when the outcome of the currently chosen option was satisfactory and the last outcome of the unchosen one was not. As expected, the other manipulated variables (change frequency, the options' values, and the difference between them) had no effect on the dynamics of behavior.

The Evaluative Advantage of Novel Alternatives: An Information-Sampling Account.

New products, services, and ideas are often evaluated more favorably than similar but older ones. Although several explanations of this phenomenon have been proposed, we identify an overlooked asymmetry in information about new and old items that emerges when people seek positive experiences and learn about the qualities of (noisy) alternatives by experiencing them. The reason for the asymmetry is that people avoid rechoosing alternatives that previously led to poor outcomes; hence, additional feedback on their qualities is precluded. Negative quality estimates, even when caused by noise, thus tend to persist. This negative bias takes time to develop, and affects old alternatives more strongly than similar but newer alternatives. We analyze a simple learning model and demonstrate the process by which people would tend to evaluate a new alternative more positively than an older alternative with the same payoff distribution. The results from two experimental studies (Ns = 769 and 805) support the predictions of our model.

Anomalies in the detection of change: When changes in sample size are mistaken for changes in proportions.

Detecting changes, in performance, sales, markets, risks, social relations, or public opinions, constitutes an important adaptive function. In a sequential paradigm devised to investigate detection of change, every trial provides a sample of binary outcomes (e.g., correct vs. incorrect student responses). Participants have to decide whether the proportion of a focal feature (e.g., correct responses) in the population from which the sample is drawn has decreased, remained constant, or increased. Strong and persistent anomalies in change detection arise when changes in proportional quantities vary orthogonally to changes in absolute sample size. Proportional increases are readily detected and nonchanges are erroneously perceived as increases when absolute sample size increases. Conversely, decreasing sample size facilitates the correct detection of proportional decreases and the erroneous perception of nonchanges as decreases. These anomalies are however confined to experienced samples of elementary raw events from which proportions have to be inferred inductively. They disappear when sample proportions are described as percentages in a normalized probability format. To explain these challenging findings, it is essential to understand the inductive-learning constraints imposed on decisions from experience.

When Unequals Compete: Where Do They Stand After the Competition?

When two unequals compete, the stronger, more able, richer competitor commonly stands a better chance of winning. If the stronger competitor does win, this worsens the relative status of the weaker competitor even further. Does this result depend on the type of competition? Does it depend on the size of the reward to be won? In the present paper, we report an experimental study of how a very simple competitive mechanism can affect the relative standing of the weaker, poorer of two competitors. In a lab experiment with 208 participants, we employed competitions with different levels of uncertainty in how a winner was determined and with different sizes of rewards to be won, to explore effects on the relative standing of the weaker and stronger competitors. We used an investment game in which participants differing in their endowed budgets competed against one another, forfeiting their investment whether they won or lost. Two versions of the game were used: a simple all-pay-auction contest and a non-constant-sum Colonel Blotto contest (Roberson & Kvasov, 2012), both with players that were unequal in their budgets. Results revealed that, in line with published game-theoretic solutions, the relative standing of the weaker agents worsened following competition, and increasingly so the higher the rewards. At the same time, the effect was mitigated in the variant of the Colonel Blotto game, which involved more uncertainty in how the winner was determined.

Age-related differences in strategic competition.

Understanding how people of different ages decide in competition is a question of theoretical and practical importance. Using an experimental laboratory approach, this research investigates the ability of younger and older adults to think and act strategically with equal or unequal resources. In zero-sum games of resource allocation, younger adults (19-35 years) and older adults (65-81 years) made strategic decisions in competition against opponents of a similar age (Study 1; N = 120) or different age (Study 2; N = 120). The findings highlight people's ability to make good interpersonal decisions in complex scenarios: Both younger and older adults were aware of their relative strength (in terms of material resources) and allocated their resources adaptively. When competing against opponents of a similar age, people's gains were in line with game-theoretic predictions. However, younger adults made superior strategic allocations and won more frequently when competing against older adults. Measures of fluid cognitive and numerical abilities correlated with strategic behavior in interpersonal competition.

Myopic reactivity in repeated-choice: The case of competing with others for a scarce, unevenly distributed resource.

Foraging for a scarce resource takes place when fewer resource-units than agents are distributed among several locations and agents choose at which location to look for the resource. But how do foragers distribute themselves over the different locations? Optimal foraging theory postulates that the distribution of agents should match the distribution of resource units (ideal free distribution [IFD]), but research with animals and humans has revealed undermatching at the location at which the resource is most abundant. For the IFD to be reached, full information about other foragers' choices and outcomes is required, information that is usually not available. We conducted a theoretical analysis of the implications of relying on different levels of information: on the incomplete, but still valid information usually available in foraging scenarios and on full information. The analysis demonstrates that myopic reactivity to disappointment, or to regret, which are likely to arise in the wake of incomplete information, leads to undermatching, with either affect leading to different degrees of undermatching. Importantly, these analyses indicate that behavior would be sensitive not only to resource distribution (as in IFD), but also to its overall abundance. Three experiments employing incentivized repeated choices were conducted. The information provided to participants, the number of locations, and resource abundance were manipulated to test the predictions of the models. Analyses of aggregate choice probabilities and trial-to-trial choice dynamics indicate that myopic reactivity to regret provides the best explanation for the observed data. With more information available, behavior matches more closely the IFD predictions. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Metacognitive myopia in change detection: A collective approach to overcome a persistent anomaly.

Going beyond the origins of cognitive biases, which have been the focus of continued research, the notion of metacognitive myopia refers to the failure to monitor, control, and correct for biased inferences at the metacognitive level. Judgments often follow the given information uncritically, even when it is easy to find out or explicitly explained that information samples are misleading or invalid. The present research is concerned with metacognitive myopia in judgments of change. Participants had to decide whether pairs of binomial samples were drawn from populations with decreasing, equal, or increasing proportions p of a critical feature. Judgments of p changes were strongly affected by changes in absolute sample size n, such that only increases (decreases) in p that came along with increasing (decreasing) n were readily detected. Across 4 experiments these anomalies persisted even though the distinction of p and n was strongly emphasized through outcome feedback and full debriefing (Experiment 1-4), simultaneous presentation (Experiments 2-4), and recoding of experienced samples into descriptive percentages (Experiment 3-4). In Experiment 4, a joint attempt was made by 10 scientists working in 7 different institutions to develop an effective debiasing training, suggesting how multilab-collaboration might improve the quality of science in the early stage of operational research designing. Despite significant improvements in change judgments, debiasing treatments did not eliminate the anomalies. Possible ways of dealing with the metacognitive deficit are discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Base rates, contingencies, and prediction behavior.

A skew in the base rate of upcoming events can often provide a better cue for accurate predictions than a contingency between signals and events. The authors study prediction behavior and test people's sensitivity to both base rate and contingency; they also examine people's ability to compare the benefits of both for prediction. They formalize these notions and propose a new measure of the regularity in the environment (ExpPA). In two experiments they test whether the notions underlying this measure capture prediction behavior. In the first experiment, they compare participants' prediction behavior, preference, and assessment of contingencies in two data sets that differ only in their base rate. In the second, in which the contribution of contingency over base rate is manipulated, they study participants' willingness to forgo a costly predictor. Results indicate a close correspondence between ExpPA and behavior.

Binding lies.

Do we feel bound by our own misrepresentations? Does one act of cheating compel the cheater to make subsequent choices that maintain the false image even at a cost? To answer these questions we employed a two-task paradigm such that in the first task the participants could benefit from false reporting of private observations whereas in the second they could benefit from making a prediction in line with their actual, rather than their previously reported observations. Thus, for those participants who inflated their report during the first task, sticking with that report for the second task was likely to lead to a loss, whereas deviating from it would imply that they had lied. Data from three experiments (total N = 116) indicate that, having lied, participants were ready to suffer future loss rather than admit, even if implicitly, that they had lied.

Strategic interactions, affective reactions, and fast adaptations.

We studied repeated choices under uncertainty in situations in which the source of uncertainty is the choice of an interaction partner. In 1 experiment the participants engaged in repeated decisions in a mixed motive game; in another experiment the options and outcomes were identical to those in the 1st, but periods of the mixed-motive game alternated with periods of a coordination game, with the change in period not announced. We analyzed choice dynamics-the relationship between an outcome and the choice that followed-and aggregate choice probabilities to gauge the relative merit of reward-based or affect-based accounts (the affects considered being disappointment and regret). In both experiments choice dynamics were essentially identical and were compatible with only the regret-based account. This was true irrespective of the game played or the stage (early or late) of the game. Moreover, the same dynamics explained the very different aggregate probabilities with which the 2 options were chosen in the 2 games and the remarkably fast adaptations to unannounced changes in the game played.

Rivals in the dark: how competition influences search in decisions under uncertainty.

In choices between uncertain options, information search can increase the chances of distinguishing good from bad options. However, many choices are made in the presence of other choosers who may seize the better option while one is still engaged in search. How long do (and should) people search before choosing between uncertain options in the presence of such competition? To address this question, we introduce a new experimental paradigm called the competitive sampling game. We use both simulation and empirical data to compare search and choice between competitive and solitary environments. Simulation results show that minimal search is adaptive when one expects competitors to choose quickly or is uncertain about how long competitors will search. Descriptively, we observe that competition drastically reduces information search prior to choice.

Do the weak stand a chance? Distribution of resources in a competitive environment.

When two agents of unequal strength compete, the stronger one is expected to always win the competition. This expectation is based on the assumption that evaluation of performance is complete, hence flawless. If, however, the agents are evaluated on the basis of only a small sample of their performance, the weaker agent still stands a chance of winning occasionally. A theoretical analysis indicates that, to increase the chance of this happening the weaker agent ought to give up on enough occasions so that he or she can match the stronger agent on the remaining ones. We model such a competition in a game, present its game-theoretic solution, and report an experiment, involving 144 individuals, in which we tested whether players (both weak and strong) are actually sensitive to their relative strengths and know how to allocate their resources accordingly. Our results indicate that they do.

Choosing between adaptive agents: some unexpected implications of level of scrutiny.

Even with ample time and opportunity to use extensive data, people often make do with small samples, which increases their risk of making the wrong decision. A theoretical analysis indicates, however, that when the decision involves continually selecting among competing, adaptive agents who are eager to be selected, an error-prone evaluation may be beneficial to the decision maker. In this case, the chance of an error can motivate competitors to exert greater effort, improving their level of performance--which is the prime concern of the decision maker. This theoretical argument was tested empirically by comparing the effects of two levels of scrutiny of performance. Results show that minimal scrutiny can indeed lead to better performance than full scrutiny, and that the effect is conditional on a bridgeable difference between the competitors. We conclude by pointing out that small-sample-based, error-prone decisions may also maintain competition and diversity in the environment.

Selective attention as tuning: the case of stroke weight.

It has long been demonstrated that when grouping occurs, attention transfer between grouped elements is facilitated, as compared with attention transfer between elements-similarly distant-that are not grouped. This has been shown for grouping by connectedness, by orientation, and by color. The present article extends these findings to the case of similarity in coarseness. By using spatial cuing to elements drawn with different strokes, it is shown that the visual processing of elements that sharestroke heaviness with the cued element is more efficient than that of elements that do not. Three experiments, in which cue validity regarding the target's location and/or its stroke is manipulated, show that the facilitation has both an endogenous and an exogenous component. The findings are discussed in terms of visual tuning to the features of a stimulus, with tuning being the initial stage of visual processing required for identification and discrimination. It is proposed that grouping, rather than explaining the facilitation observed, can be explained by the notion of visual tuning to features. The findings also point to potential methodological pitfalls when different stroke weights are used, unintentionally, in visual displays.

The mysteries of the diagonal: gender-related perceptual asymmetries.

In this article, we report a perceptual asymmetry for the two diagonals that is related to gender in that females prefer the diagonal spanning from top right to bottom left (/) whereas males prefer the opposite (\). This relationship is observed in a variety of tasks, including aesthetic judgment of paintings, spotting differences between two paintings, and visual search for a tilted line among similarly tilted distractors. This article does not provide an explanation of the relationship between this asymmetry and gender but rules out several potential mediating factors, such as eye dominance, head tilt, handedness, and hemispheric differences. At the same time, the scope of the phenomenon is outlined: The asymmetry is found for both meaningful and meaningless stimuli and in both brief and extended presentations. Moreover, the asymmetry is found to be related to the tilt of the visual elements that require processing, not to their location in the visual field.