Ro'i Zultan bgu logo

picture of Ro'i

I’m an experimental economist with background in cognitive and experimental psychology. I’m mainly interested in understanding how groups shape cognitions and behavior as well as in more broad issues of cooperation and behavior in teams. I’m also interested in some basic game theoretical issues, experimental auctions, and experimental methodology.

I’m currently a senior lecturer at the department of economics at Ben-Gurion University of Negev and the director of the Negev Experimental Economics Laboratory. I'm also a member of the Center for Decision Making and Economic Psychology.

Recent publications

  • Eva-Maria Steiger and Ro'i Zultan (2014). See No Evil: Information Chains and Reciprocity. Journal of Public Economics, 109, 1-12. [PDF]
    Being observed leads people to increase their effort in anticipation of positive reciprocity. Observing others increases the chance of observing a shirker and negatively reciprocating by shirking. Partial transparency, in which individuals only observe the previous mover leads to the highest effort.
  • Esteban Klor, Sebastian Kube, Eyal Winter and Ro'i Zultan (2014). Can Higher Rewards Lead to Less Effort? Incentive Reversal in Teams. Journal of Economic Behavior & Organization, 97, 72-83. [PDF]
    We show in two experiments that increasing team bonuses (or equivalently reducing effort costs) can reduce effort due to complementarities between agents.

Working papers:

  • Auction Mechanisms and Bidder Collusion: Bribes, Signals and Selection (with Aniol Llorente-Saguer) [PDF]
    We show that first-price auctions lead to worse outcomes than second-price auctions under collusion. This counters existing theoretical results, which do not consider the implications of failed collusive negotiations for bidding behavior.
  • Auctions and Leaks: A Theoretical and Experimental Investigation (with Sven Fischer, Werner Güth, and Todd Kaplan [PDF]
    We analyze bidding when the bid of one bidder may be revealed to the other bidder. Multiple equilibria exist in second-price auction. We find experimental evidence for different types of bidding behavior. Nonetheless, behavior and outcomes are, on average, similar to the no-leaks baseline.
  • Punishment and Reward Institutions with Harmed Minorities (with Sagi Dekel and Sven Fischer) [PDF]
    We study voluntary contributions to public goods that are someone's public bad. Punishment has no significant effect on contributions, possibly because the lowest contributor—who is usually the one who should be punished—has a justification for not contributing. Majority players increase their contributions if they can compensate the harmed minority—only when communication is available.
  • Job Search Costs and Incentives (with Andriy Zapechelnyuk) [PDF]
    Making jobs easier to find can improve job market efficiency. In an environment of fixed contracts and moral hazard, however, some individuals may be incentivized to shirk on the job at the cost of being fired and having to find a new job. This leads to an overall reduction of productivity and wages in the market and a loss of social welfare.
  • Social Motives in Intergroup Conflict and Cooperation (with Ori Weisel) [PDF]
    Why does intergroup conflict mobilize individuals for collective action? We experimentally disentangle three different social motives.

Research

Journal articles:

Incentives in teams and public goods

  • Eva-Maria Steiger and Ro'i Zultan (2014). See No Evil: Information Chains and Reciprocity. Journal of Public Economics, 109, 1-12. [PDF]
    Being observed leads people to increase their effort in anticipation of positive reciprocity. Observing others increases the chance of observing a shirker and negatively reciprocating by shirking. Partial transparency, in which individuals only observe the previous mover leads to the highest effort.
  • Esteban Klor, Sebastian Kube, Eyal Winter and Ro'i Zultan (2014). Can Higher Rewards Lead to Less Effort? Incentive Reversal in Teams. Journal of Economic Behavior & Organization, 97, 72-83. [PDF]
    We show in two experiments that increasing team bonuses (or equivalently reducing effort costs) can reduce effort due to complementarities between agents.
  • M. Vittoria Levati and Ro'i Zultan (2011). Cycles of Conditional Cooperation in a Real-Time Voluntary Contribution Mechanism. Games, 2(1), 1-15. [PDF]
    We develop a measure of conditional cooperation in a real-time contribution setting.
  • Sebastian Goerg, Sebastian Kube and Ro'i Zultan (2010). Treating Equals Unequally - Incentives in Teams, Workers' Motivation and Production Technology. Journal of Labor Economics, 28, 747-772. [PDF]
    We show experimentally that arbitrary wage discrimination can increase agents' effort by solving the coordination problem that arises under equal wages with complementarities between agents.

Groups and conflict

  • David Hugh-Jones and Ro'i Zultan (2013). Reputation and Cooperation in Defence. Journal of Conflict Resolution, 57(2), 364-392. [PDF]
    An outside threat increases in-group cooperation. We provide a game-theoretical and evolutionary explanation for the effect based on group reputation.

Responsibility in teams

  • David Lagnado, Tobias Gerstenberg and Ro'i Zultan (2014). Causal responsibility and counterfactuals. Cognitive Science, 37(6), 1036-1073.
    We develop and test a framework for assigning responsibility in teams. Ex-post responsibility is a function of ex-ante criticality and ex-post counterfactual pivotality.
  • Ro'i Zultan, Tobias Gerstenberg and David Lagnado (2012). Finding Fault: Causality and Counterfactuals in Group Attributions. Cognition 125, 429-440. [PDF]
    We show that, consistent with counterfactual causal reasoning, blame assigned to a team member increases (decreases) with the performance of complementing (substitute) peers.

Game theory

  • M. Vittoria Levati, Matthias Uhl and Ro'i Zultan (2014). Imperfect Recall and Time Inconsistencies: An experimental test of the absentminded driver "paradox". International Journal of Game Theory, 43, 65-88. [PDF]
    Piccione and Rubinstein (1997) argued that the optimal strategy of absentminded decision makers may change over time even in the absence of any new information. We provide supporting experimental results.
  • Ro'i Zultan (2013). Timing of Messages and the Aumann Conjecture: A multiple-Selves Approach. International Journal of Game Theory, 42, 789-800. [PDF]
    Does it matter whether people send a message about intentions or about actions? I show that the puzzling experimental results of Charness (2000) can be rationalized if the formal modelling of the game separates the action and the message.

Communication and cooperation

  • Ro'i Zultan (2012). Strategic and Social Pre-Play Communication in the Ultimatum Game. Journal of Economic Psychology 33(3), 425-434. [PDF]
    I show that strategic and pure social communication lead to similar outcomes—but working through different channels.
  • Ben Greiner, Werner Güth and Ro'i Zultan (2012). Social Communication and Discrimination: A Video Experiment. Experimental Economics, 15(3), 398-417. [PDF]
    Mere exposure to others doesn't increase generosity. We find that although there is no effect on average, there are idiosyncratic effects based on impression formation. We establish causality using video technology.
  • Carsten Schmidt and Ro'i Zultan (2005). The Uncontrolled Social Utility Hypothesis Revisited. Economics Bulletin 3, 1-7. [PDF]
    Preliminary results disentangling strategic and pure social communication.

Judgment and decision making

  • Ro'i Zultan, Maya Bar-Hillel and Nitsan Guy (2010). When Being Wasteful Is Better than Feeling Wasteful. Judgment and Decision Making, 7(5), 489-496. [PDF]
    Paying a fixed price for a service can be ex-post wasteful if it turns out that the required service would have been cheaper on a per-use basis.

Other publications:

  • Maya Bar-Hillel and Ro'i Zultan (2012). We Sing the Praise of Good Displays: How Gamblers Bet in Casino Roulette. CHANCE 25(2), 27-30 [PDF]
  • Carsten Schmidt and Ro'i Zultan (2007). Unilateral Face-to-Face Communication in Ultimatum Bargaining – A Video Experiment. In Oxley, L. and Kulasiri, D. (eds) MODSIM 2007 International Congress on Modelling and Simulation. Modelling and Simulation Society of Australia and New Zealand, 1205-1211 [PDF]

About me

“Earth water fire and air
Met together in a garden fair
Put in a basket bound with skin
If you answer this riddle, you'll never begin…”

Contact

Department of Economics
Ben-Gurion University of the Negev
Building 72, Room 449
Phone: +972 (0) 8 647 2306 (x72306)
E-mail: zultan(ad)bgu.ac.il