This paper discusses aspects of recruiting subjects for economic laboratory experiments, and shows how the Online Recruitment System for Economic Experiments can help. The software package provides experimenters with a free, convenient, and very powerful tool to organize their experiments and sessions.

There is growing evidence that not all experimental subjects understand their strategic environment. We introduce a “choice process” (CP) protocol that aids in identifying these subjects. This protocol elicits in an incentive compatible manner provisional choices as players internalize their decision making environment. We implement the CP protocol in the modified 2/3 guessing game and use it to pinpoint players that are naive by identifying those who make weakly dominated choices some time into the play. At all time horizons these players average close to 50. This is consistent with the assumption in Level-K theory that the least sophisticated subjects (the naive ones) play uniformly over the [1–100] action space. In contrast, sophisticated players show evidence of increased understanding as time passes. We find that the CP protocol mirrors play in multiple setups with distinct time constraints. Hence it may be worth deploying more broadly to understand the interaction between decision time and choice.

LIONESS Lab is a free web-based platform for interactive online experiments. An intuitive, user-friendly graphical interface enables researchers to develop, test, and share experiments online, with minimal need for programming experience. LIONESS Lab provides solutions for the methodological challenges of interactive online experimentation, including ways to reduce waiting time, form groups on-the-fly, and deal with participant dropout. We highlight key features of the software, and show how it meets the challenges of conducting interactive experiments online.

Real-effort experiments are frequently used when examining a response to incentives. For a real-effort task to be well suited for such an exercise its measurable output must be sufficiently elastic over the incentives considered. The popular slider task in Gill and Prowse (Am Econ Rev 102(1):469–503, 2012) has been characterized as satisfying this requirement, and the task is increasingly used to investigate the response to incentives. However, a between-subject examination of the slider task’s response to incentives has not been conducted. We provide such an examination with three different piece-rate incentives: half a cent, two cents, and eight cents per slider completed. We find only a small increase in performance: despite a 1500 % increase in the incentives, output only increases by 5 %. With such an inelastic response we caution that for typical experimental sample sizes and incentives the slider task is unlikely to demonstrate a meaningful and statistically significant performance response.

We use a revealed preference approach to disentangle conformity, an intrinsic taste to follow others, from information-driven herding. We provide observations from a series of sequential decision-making experiments in which subjects choose the type of information they observe before making their decision. Namely, subjects choose between observing a private (statistically informative) signal or the history of play of predecessors who have not chosen a private signal (i.e., a statistically uninformative word-of-mouth signal). In our setup, subjects choose the statistically uninformative social signal $34\%$ of the time and, of those, $88\%$ follow their observed predecessors’ actions. When allowing for payoff externalities by paying subjects according to the collective action chosen by majority rule, the results are amplifed and the social signal is chosen in $51\%$ of all cases, and $59\%$ of those who pick the social signal follow the majority choice. The results from the majority treatment demonstrate that conformist behavior is not driven by inequality aversion, nor by strategic voting behavior in which voters balance others who are uninformed. Raising the stakes five-fold does not eliminate conformist behavior; in both treatments, the social signal is chosen nearly $50\%$ of the time. Individual level analysis yields the identification of rules of thumb subjects use in making their decisions.

Online experiments allow researchers to collect datasets at times not typical of laboratory studies. We recruit 2336 participants from Amazon Mechanical Turk to examine if participant characteristics and behaviors differ depending on whether the experiment is conducted during the day versus night, and on weekdays versus weekends. Participants make incentivized decisions involving prosociality, punishment, and discounting, and complete a demographic and personality survey. We find no time or day differences in behavior, but do find that participants at nights and on weekends are less experienced with online studies; on weekends are less reflective; and at night are less conscientious and more neurotic. These results are largely robust to finer-grained measures of time and day. We also find that those who participated earlier in the course of the study are more experienced, reflective, and agreeable, but less charitable than later participants.

We investigate the effectiveness of two leadership institutions in each of two games: a weakest link and a linear public good game. An “Exemplar” leader is a first mover who commits to a level of contribution; a “Manager” is a first mover who makes cheap talk suggestions to the team members. Our results show that both leadership institutions reduce coordination failures as compared to a simultaneous move, baseline scenario with no leader. Although the Manager treatment seems to be slightly more effective at the outset, both leadership institutions significantly and equally improve contributions in the coordination game over time. According to our results none of the leadership institutions seem effective in the linear public good game. This may be due to the fact that our marginal per capita return is rather large, keeping the contribution levels high regardless of the treatment. Subjects who choose to free ride continue to do so with or without leaders, and subjects who choose to be cooperative do not become discouraged by others’ lack of cooperation. These results both replicate earlier findings and allow direct comparison across similar games.

We investigate the Baron-Ferejohn (The American Political Science Review 83(4): 1181–1206, 1989) model of legislative bargaining with cheap talk between the designated proposer and potential coalition partners. Communication results in substantially increased proposer power close to the stationary subgame perfect equilibrium prediction. This is achieved primarily through voters competing with each other to get the proposer to include them in the winning coalition, while arguing for a zero allocation for redundant voters. Voters typically follow through on their stated reservation shares, but proposers often fail to partner with voters making excessively low offers, as these are more likely to be reneged on.

Laboratory experiments have been often replaced by online experiments in the last decade. This trend has been reinforced when academic and research work based on physical interaction had to be suspended due to restrictions imposed to limit the spread of Covid-19. Therefore, data quality and results from web experiments have become an issue which is currently investigated. Are there significant differences between lab experiments and online findings? We contribute to this debate via an experiment aimed at comparing results from a novel online protocol with traditional laboratory settings, using the same pool of participants. We find that participants in our experiment behave in a similar way across settings and that there are at best weakly significant and quantitatively small differences in behavior observed using our online protocol and physical laboratory setting.

In this article, we highlight how simulation methods can be used to analyze power of economic experiments. We provide the powerBBK package programmed for experimental economists, that can be used to perform simulations in STATA. Power can be simulated using a single command line for various statistical tests (nonparametric and parametric), estimation methods (linear, binary, and censored regression models), treatment variables (binary, continuous, time-invariant or time varying), sample sizes, experimental periods, and other design features (within or between-subjects design). The package can be used to predict minimum sample sizes required to reach a user-specific level of power, to maximize power of a design given the researcher supplied a budget constraint, or to compute power to detect a user-specified treatment order effect in within-subjects designs. The package can also be used to compute the probability of sign errors—the probability of rejecting the null hypothesis in the wrong direction as well as the share of rejections pointing in the wrong direction. The powerBBK package is provided as an .ado file along with a help file, both of which can be downloaded here (http://www.bbktools.org).

We measure time preferences in a sample of 561 children aged 7–11 years. Using a within-subject design, we compare the behavior of our subjects using two distinct experimental measures of time preferences: a standard choice list with multiple decisions and a single choice time-investment-exercise requiring one decision only. We find that both measures yield very similar aggregate results, correlate significantly within subjects and can be explained by basically the same explanatory variables. Advantages and disadvantages of both measures are discussed. Our findings are relevant for the design of experiments to measure time preferences.

This paper reports data from three subject pools (n = 717 subjects) using techniques based on those of Loewenstein et al. (J Personal Soc Psychol 57:426–441, 1989) and Blanco et al. (Games Econ Behav 72:321–338, 2011) to obtain parameters, respectively, of stated and revealed inequality aversion. We provide a replication opportunity for those papers, with two innovations: (1) a design which allows stated and revealed preferences to be compared at the individual level; (2) assessment of robustness of findings across subjects from a UK university, a Turkish university and Amazon Mechanical Turk. Our findings on stated aversion to inequality are qualitatively similar to those of Loewenstein et al. in each of our subject pools, whereas there are notable differences between some of our findings on revealed preference and those of Blanco et al. We find that revealed advantageous inequality aversion is often stronger than revealed dis-advantageous inequality aversion. In most subject pools, we find some (weak) correlation between corresponding parameters of stated and revealed inequality aversion.

We perform a meta analysis of gender differences in the standard windfall gains dictator game (DG) by collecting raw data from 53 studies with 117 conditions, giving us 15,016 unique individual observations. We find that women on average give 4 percentage points more than men (Cohen’s $d=0.16$), and that this difference decreases to $3.1\%$ points (Cohen’s $d=0.13$) if we exclude studies where dictators can only give all or nothing. The gender difference is larger if the recipient in the DG is a charity, compared to the standard DG with an anonymous individual as the recipient (a 10.9 versus a $2.3\%$ points gender difference). These effect sizes imply that many individual studies on gender differences are underpowered; the median power in our sample of standard DG studies is only $9\%$ to detect the meta-analytic gender difference at the $5\%$ significance level. Moving forward on this topic, sample sizes should thus be substantially larger than what has been the norm in the past.

The hypothesis that intuition promotes cooperation has attracted considerable attention. Although key results in this literature have failed to replicate in pre-registered studies, recent meta-analyses report an overall effect of intuition on cooperation. We address the question with a meta-analysis of 82 cooperation experiments, spanning four different types of intuition manipulations—time pressure, cognitive load, depletion, and induction—including 29,315 participants in total. We obtain a positive overall effect of intuition on cooperation, though substantially weaker than that reported in prior meta-analyses, and between studies the effect exhibits a high degree of systematic variation. We find that this overall effect depends exclusively on the inclusion of six experiments featuring emotion-induction manipulations, which prompt participants to rely on emotion over reason when making allocation decisions. Upon excluding from the total data set experiments featuring this class of manipulations, between-study variation in the meta-analysis is reduced substantially—and we observed no statistically discernable effect of intuition on cooperation. Overall, we fail to obtain compelling evidence for the intuitive cooperation hypothesis.

Cason and Plott (J Polit Econ, 122(6):1235–1270, 2014) show that subjects’ misconception about the incentive properties of the Becker-DeGroot-Marschak (BDM) value elicitation procedure can generate data patterns that look like—and might thus be misinterpreted as evidence for—preferences constructed from endowments or reference points. We test whether game form misconceptions are necessary to produce willingness-to-pay (WTP) vs. willingness-to-accept (WTA) gaps in a valuation experiment in which subjects are randomly assigned to the role of either buyer or seller. We employ a design that allows us to identify whether a subject understood the incentive properties of a price-list version of the BDM mechanism. We find a robust WTP-WTA gap, even among subjects whose elicited valuations for a good of induced and known monetary value and whose ability to identify the payoffs resulting from their choices indicate an understanding of the incentive properties of the BDM mechanism. We conclude that game form misconceptions are not a necessary condition for the emergence of WTP-WTA gaps.

We investigate how different forms of scrutiny affect dishonesty, using Gneezy’s [Am Econ Rev 95:384–394 (2005)] deception game. We add a third player whose interests are aligned with those of the sender. We find that lying behavior is not sensitive to revealing the sender’s identity to the observer. The option for observers to communicate with the sender, and the option to reveal the sender’s lies to the receiver also do not affect lying behavior. Even more striking, senders whose identity is revealed to their observer do not lie less when their interests are misaligned with those of the observer.

The Internet presents today’s researchers with unprecedented opportunities to conduct field experiments. Using examples from Economics and Computer Science, we present an analysis of the design choices, with particular attention to the underlying technologies, in conducting online field experiments and report on lessons learned.

A number of recent papers have looked at framing effects in linear public good games. In this comment, I argue that, within this literature, the distinction between give-take and positive–negative framing effects has become blurred, and that this is a barrier towards understanding the experimental evidence on framing effects. To make these points, I first illustrate that frames can differ along both an externality and choice dimension. I then argue that the existing evidence is consistent with a strong positive–negative framing effect but no give-take framing effect on average contributions.

We propose a framework for identifying discrete behavioural types in experimental data. We re-analyse data from six previous studies of public goods voluntary contribution games. Using hierarchical clustering analysis, we construct a typology of behaviour based on a similarity measure between strategies. We identify four types with distinct stereotypical behaviours, which together account for about 90% of participants. Compared to the previous approaches, our method produces a classification in which different types are more clearly distinguished in terms of strategic behaviour and the resulting economic implications.

Governments across the world have implemented restrictive policies to slow the spread of COVID-19. Recommended face mask use has been a controversially discussed policy, among others, due to potential adverse effects on physical distancing. Using a randomized field experiment (N = 300), we show that individuals kept a significantly larger distance from someone wearing a face mask than from an unmasked person during the early days of the pandemic. According to an additional survey experiment (N = 456) conducted at the time, masked individuals were not perceived as being more infectious than unmasked ones, but they were believed to prefer more distancing. This result suggests that wearing a mask served as a social signal that led others to increase the distance they kept. Our findings provide evidence against the claim that mask use creates a false sense of security that would negatively affect physical distancing. Furthermore, our results suggest that behavior has informational content that may be affected by policies.