Publications and Research

Hart, E., & Schweitzer, M. E. (in prep) Getting Less: When negotiating harms post-agreement performance.

Hart, E., Avrahami, J., & Kareev, Y. (under review). The strong, the weak, and lady luck: The motivating power of uncertainty in competitions between unequal competitors.

Hart, E., Bicchieri, C., & Mellers, B. (under review). Bad luck or bad intentions: When do third party observers reveal offender’s intentions to victims?

Hart, E., Avrahami, J., & Kareev, Y. (2016). Enlarging the Market Yet Decreasing the Profit: Competitive Behavior When Investment Affects the Prize. Judgment and Decision Making, 11(4), 380-390. Abstract

In many competitive situations, our investments increase our gains: Developing better products or research proposals may lead to higher contracts or patents or larger grants. Does increasing investment in such cases always guarantee higher gains? We used an experimental repeated competition game in which prizes depended on contestants’ investments (n=108). Contestants invested more when they increased the potential prize (“enlarge the market”), yet in some cases this tendency was counterproductive (“decrease the profit”): Contestants in fact diminished their earnings, compared to sitting out the competition and keeping their initial funds. Moreover, when a contestant’s investment decreased an opponent’s prize, the contestant tended to invest less; this effect, in turn, led to higher overall gains for both contestants. This result implies that prosocial considerations are at play. Notably, in certain situations, excessive competitive tendencies may lead to a larger waste of resources.


Shen, Q., Teo, M., Winter, E., Hart, E., Chew, S. H., & Ebstein, R.P. (2016). To cheat or not to cheat: Tryptophan hydroxylase 2 SNP variants contribute to dishonest behavior. Frontiers in Behavioral Neuroscience, 10, 82.

Hart, E., Avrahami, J., Kareev, Y., & Todd, P. M. (2015). Investing Even in Uneven Contests: Effects of Asymmetry on Investment in Contests. Journal of Behavioral Decision Making, 28(4), 395–409. Paper (@ Journal) Abstract

Many competitions, such as political campaigns, innovative endeavors, sports or courting rituals, require investment of non-refundable resources: One contestant wins the prize for the invested amount, while all others lose their investments without receiving compensation. Frequently, contests are asymmetric, due to differing resources or prize valuations. Does asymmetry discourage the weaker players from investing? Do stronger players take this into account, and also invest less? Or does the desire to win abolish these differences? Two experiments explored the effects of asymmetry between the contestants – arising from their resources or prizes – on non-refundable investments. Subjects repeatedly competed in both symmetric and asymmetric contests, enabling within-subject comparisons. We observed an effect of asymmetry only when it concerned resources: Subjects overall invested less when their resources were unequal, whereas inequality in the prizes did not influence investments; this pattern suggests that winning itself is motivating. The changes between consecutive investments can be explained by reactions to the previous outcome (win or loss): Across all contests, investment decreased following a win, and increased following a loss.


Hart, E., Kareev, Y., & Avrahami, J. (2015). Good Times, Bad Times: Reversal of Risky Choice in a Good versus a Bad World. Decision, 3(2), 132-145. Paper (@ Journal) Abstract

In many situations one has to choose between risky alternatives, based only on one's past experience with these alternatives. Such decisions can be made in more – or less – benevolent states of the world. Predictions concerning two crucial aspects of choice behavior – the overall probability of choosing the riskier alternative and the round-to-round choice dynamics – depend on how one evaluates one’s payoff: Whether in its own right, compared to possible outcomes within the chosen alternative (which could result in disappointment), or compared to foregone outcomes, those of other, unchosen alternatives (which could result in regret). In two experiments, subjects made repeated, incentivized choices between two gambles, one riskier than the other, neither offering a sure amount. We explored whether and how choices are affected by the state of world in which they are made. States were manipulated both between-subjects (Experiment 1, N=144) and within-subjects (Experiment 2, N=132). We observed a significant effect of state on overall choice probability: In more benevolent states, subjects tended to choose the riskier alternative, and vice versa in worse states; choice dynamics were similar across states, and were most strongly affected by reactions to the forgone payoff. These patterns of results are in line with a regret-based account.


Avrahami, J., Kareev, Y., & Hart, E. (2014). Taking the Sting out of Choice? Diversification of Investments. Judgment and Decision Making, 9(5), 373-386. Paper (@ Journal) Abstract

It is often the case that one can choose a mix of alternative options rather than have to select one option only. Such an opportunity to diversify may blunt the risk involved in all-or-none choice. Here we investigate repeated investment decisions in two-valued options that differ in their riskiness, looking for the effects of recent decisions and their outcomes on upcoming decisions. We compare these effects to those evident in all-or-none choice between the same risky options. The ‘state of the world’, namely, the likelihood of the high versus the low outcomes of the options is manipulated. We find that aggregate allocation diverges from uniformity (i.e., from 1/n), and is sensitive to outcome probabilities with the pattern of results indicating reactivity to the outcome of the previous decision. Round-to-round dynamics reveal that the outcome of the previous decision has an effect on the subsequent decision, on top of inertia; the aspects of the outcome that influence the next decision indicate an effect of a missed opportunity, if there was one, in the previous decision. Importantly, recent outcomes have a similar effect in diversification decisions and in all-or-none choice. Close

Israel, S., Hart, E., & Winter, E. (2014). Oxytocin Decreases Accuracy in the Perception of Social Deception. Psychological Science, 25, 293-295. Paper (@ Journal) Abstract

Social interactions such as coalition formation, negotiation and bargaining, all involve the ability to mask, and uncover, non-cooperative intentions. However, the psychobiological factors underlying the identification of deception remain poorly understood. Our study explored the role of oxytocin (OT) – a neuropeptide with marked effects on social cognition and behavior – on the ability to differentiate between authentic and falsely presented cooperative intentions within a televised social (prisoners') dilemma. We demonstrate that subjects were able to accurately differentiate between cooperators and defectors, and that this ability was negatively impacted by administration of OT. We conjecture that this impairment is characterized by less social vigilance in detecting deceptive behavior. Our findings place a cautionary note on the use of OT as a tool for decoding others' intentions, particularly in the all too common context where mixed motives may lurk behind the veil of a seemingly friendly face.


Selected Works in Progress

Hart, E., Campagna, R., Curhan, J., & Elfenbein, H. A. Negotiation and work motivation over time.

Hart, E., & Bowles, H. R. Win-win and task negotiations.

Hart, E., Marciano, D., & Winter, E. Groups, group members and individuals: Choices and impulses in repeated risky decisions.


Ph.D Thesis (2015). Costly Contests and the Will to Win. Advisors: Prof. Yaakov Kareev, Dr. Judith Avrahami. Paper (PDF) Abstract

Competitions are ubiquitous in plant, animal and human societies – for food, living space, mates; in schools, in the workplace, in sports, in research and development enterprises, in political races as well as in state conflicts and wars. Many resources are spent on such competitions – time, effort or money – investments which are often non-refundable. One contestant wins the prize for the invested amount, while all others lose their investments without receiving compensation. High investments may benefit society in general, for example in innovative endeavors; yet, high investments can also be largely wasteful or even detrimental for society when the competition is exacerbated and no new wealth is created. Hence, understanding what factors determine the total investment by contestants is of much interest.
Three studies examined behavior in costly competitions using an experimental game paradigm, "Invest Game", involving repeated investment decisions. I varied the competitive setting, in order to explore whether –and how– various economic and psychological aspects affect investment behavior. I examined several aspects of investment behavior: Overall investments in the different competition settings; the corresponding earnings from the competition; earnings were compared between the different competitions, and compared to the initial resources; the dynamics of investment over time, which could show escalation or moderation of the competition; and round-to-round changes in investment, in regard to the outcome (win or loss) in the previous round.


M.A. Thesis (2010). Steal the Show: Payoff Effect on Accuracy of Behavior-Prediction in Real High-Stake Dilemmas. Advisor: Prof. Gary Bornstein Paper (PDF) Abstract

Our study explores the ability to predict players' behavior in a Prisoner's Dilemma (PD) type of game. We use "Split or Steal" video clips – a televised game show depicting a (very) high stake version of PD-esque game. Based on relevant psychological and economic literature, our main hypothesis is that motivated observers will predict the players' decisions more accurately than non-motivated observers. In order to examine the effect of incentives on prediction accuracy, we vary the reward for correct predictions; we conjecture that the bigger the reward, the more accurate the prediction. In addition, we explore correlations between the observers' accuracy and the players' decisions. We hypothesize that observers will more readily believe the players and consider them cooperators than assume that they will defect.