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We implement an experiment to elicit subjects' ambiguity attitudes in the spirit of Ellsberg's three-color urn. The procedure includes three design elements that (together) have not been featured in similar experiments: Strict ambiguity preferences, a single decision, and a mechanical randomization device with an unknown distribution (to both subjects and experimenters). We use this device in order to eliminate possible 'strategic' ambiguity related to subjects' beliefs about the experimenters' motivations. In addition, we survey 40 experimental studies on Ellsberg's two- and three-color problems, and find that, on average, slightly more than half of subjects are classified as ambiguity averse. Our results, with our new design, fall on the low end of the range of results in the surveyed studies, and are comparable to a control test where "strategic" ambiguity was induced.

In oligopoly, imitating the most successful competitor yields very competitive outcomes. This theoretical prediction has been confirmed experimentally by a number of studies. A recent paper by Friedman et al. (2015) qualifies those results in an interesting way: while they replicate the very competitive results for the first 25 to 50 periods, they show that when using a much longer time horizon of 1200 periods, results slowly turn to more and more collusive outcomes. We replicate their result for duopolies. However, with 4 firms none of our oligopolies becomes permanently collusive. Instead, the average quantity always stays above the Cournot-Nash equilibrium quantity. Thus, it seems that "four remain many" even with 1200 periods.

This study provides evidence from a laboratory experiment showing that managerial bonuses can affect adversely a manager's subordinates. In our set up, managers compete to obtain a large bonus which depends partly on the effort exerted by their subordinates. Managers can suggest an effort level and coerce subordinates who disobey by punishing them. When managers compete for individual bonuses, we find that subordinates do not obey their demands. This doubles coercion rates relative to a control treatment without bonuses. In contrast, when managers compete for pooled bonuses which give managers discretionary power over the allocation of the bonus, most subordinates exert maximal effort. Although managers share a substantial fraction of the bonus, they are not worse off than they are with an individual bonus. A model in which agents care about inequality in earnings can account for the main findings in our experiment.

Imitating the best strategy from the previous period has been shown to be an important heuristic, in particular in relatively complex environments. In this experiment we test whether subjects are more likely to use imitation if they are under stress. Subjects play a repeated Cournot oligopoly. Treatments are time pressure within the task and distractions through a second task (a Stroop-task) that has to be performed as well and influences payment. We measure stress levels through salivary cortisol measurements and through measuring the heart rate. Our main findings are that time pressure and distraction can indeed raise physiological stress levels of subjects within our task. More importantly from an economic perspective, we can also observe a corresponding behavioral change that is indicative of imitation.

In premium auctions, the highest losing bidder receives a reward from the seller. This paper studies the private value English premium auction (EPA) for different risk attitudes of bidders. We explicitly derive the symmetric equilibrium for bidders with CARA utilities and conduct an experimental study to test the theoretical predictions. In our experiment, subjects are sorted into risk-averse and risk loving groups. We find that revenues in the EPA are significantly higher when bidders are risk loving rather than risk averse. These results are partly consistent with theory and confirm the general view that bidders' risk preferences constitute an important factor that affects bidding behavior and consequently also the seller's expected revenue. However, individual subjects rarely follow the equilibrium strategy and as a result, revenue in our experiment is lower than in the symmetric equilibrium.

As illustrated by the famous Ellsberg paradox, many subjects prefer to bet on events with known rather than with unknown probabilities, i.e., they are ambiguity averse. In an experiment, we examine subjects' choices when there is an additional source of ambiguity, namely, when they do not know how much money they can win. Using a standard independence assumption, we show that ambiguity averse subjects should continue to strictly prefer the urn with known probabilities. In contrast, our results show that many subjects no longer exhibit such a strict preference. This should have important ramifications for modeling ambiguity aversion.

We show that in symmetric two-player exact potential games, the simple decision rule "imitate-if-better" cannot be beaten by any strategy in a repeated game by more than the maximal payoff difference of the one-period game. Our results apply to many interesting games including examples like 2x2 games, Cournot duopoly, price competition, public goods games, common pool resource games, and minimum effort coordination games.

The power to coerce workers is important for the efficient operation of hierarchically structured organizations. However, this power can also be used by managers to exploit their subordinates for their own benefit. We examine the relationship between the power to coerce and exploitation in a laboratory experiment where a senior and a junior player interact repeatedly for a finite number of periods. We find that senior players try repeatedly to use their power to exploit junior workers. These attempts are successful only when junior workers have incomplete information about how their effort impacts on the earnings of senior players, but not when they have complete information. Evidence from an incentive-compatible questionnaire indicates that the social acceptability of exploitation depends on whether the junior worker can detect she is being exploited. We also show how a history of exploitation affects future interactions.

Bubbles in asset markets have been documented in numerous experimental studies. However, all experiments in which bubbles occur pay dividends after each trading day. In this paper we study whether bubbles can occur in markets without dividends. We investigate the role of two features that are present in real markets. (1) The mere possibility that some traders may have inside information, and (2) the option to communicate with other traders. We find that bubbles can indeed occur without dividends. Surprisingly, communication turns out to be counterproductive for bubble formation, whereas the possibility of inside information is, as expected, crucial.

We use a simple, three-item test for cognitive abilities to investigate whether established behavioral biases that play a prominent role in behavioral economics and finance are related to cognitive abilities. We find that higher test scores on the Cognitive Reflection Test of Frederick (2005) indeed are correlated with lower incidences of the conjunction fallacy, conservatism in updating probabil-ities, and overconfidence. Test scores are also significantly related to subjects' time and risk preferences. We find no influence on anchoring. However, even if biases are lower for people with higher cognitive abilities, they still remain substantial.

Negotiations frequently end in conflict after one party rejects a final offer. In a large-scale internet experiment, we investigate whether a 24-hour cooling-off period leads to fewer rejections in ultimatum bargaining. We conduct a standard cash treatment and a lottery treatment, where subjects receive lottery tickets for several large prizes - emulating a high-stakes environment. In the lottery treatment, unfair offers are less frequently rejected, and cooling-off significantly reduces the rejection rate further. In the cash treatment, rejections are more frequent and remain so after cooling-off. This treatment difference is particularly pronounced for subjects with lower cognitive abilities.

In this note we study a very simple trial & error learning process in the context of a Cournot oligopoly. Without any knowledge of the payoff functions players increase, respectively decrease, their quantity by one unit as long as this leads to higher profits. We show that despite the absence of any coordination or punishing device this process converges to a collusive outcome.