The Effects of Goal Revelation on Computer-Mediated Negotiation Ya’akov Gal MIT CSAIL Harvard Univ. SEAS Sohan D’souza British Univ. in Dubai Philippe Pasquier Simon Fraser Univ. Abstract This paper studies a novel negotiation protocol in settings in which players need to exchange resources in order to achieve their own objective, but are uncertain about the objectives of other participants. The protocol allows participants to request each other to disclose their interests at given points in the negotiation. Revealing information about participants’ needs may facilitate agreement, but it also exposes their negotiation strategy to the exploitation of others. Empirical studies were conducted using computer-mediated negotiation scenarios that provided an analogue to the way goals and resources interact in the world. The scenarios varied in the individual positions and interests of participants, as well as the dependency relation- ships that hold between participants. Results show that those who choose to reveal their underlying goals outperform nego- tiators in the same setting that use a protocol that forbids reve- lation. In addition, goal revelation has a positive effect on the aggregate performance of negotiators, and on the likelihood to reach agreement. Further analysis show goal revelation to be a cooperation mechanism by which negotiators are able to iden- tify acceptable agreements in scenarios characterized by few socially (Pareto) beneficial outcomes. Introduction Goals and incentives are key determinants of human behavior, but in many negotiation scenarios there is lack of information about the underlying interests of participants. Often, this pre- vents the parties from reaching a beneficial agreement. Con- sider a bank who is offering to purchase the majority of shares of a struggling company in return for potential job cuts. The unions may not allow the company to accept the offer because they refuse to agree to layoffs. However, if the bank discloses that it is committed to keeping the company afloat, the unions may agree to the buy-out if layoffs are minimal. On the other hand, revealing goals is often associated with a cost. Having realized that the bank does not intend to liquidate the com- pany, the unions may demand no job cuts. This work studies the trade-offs associated with different negotiation protocols in settings where self-interested parties lack information about each other’s aims. We consider strate- gic settings which require an agreement on the allocation of scarce resources among self-interested parties. Participants take turns proposing take-it-or-leave-it deals to each other un- der time constraints, and communication is associated with a cost. With no certain knowledge of each other’s goals, the offers of participants serve as a “noisy signal” to their true objectives. It is difficult to locate efficient trades for both par- ties in such conditions, either because participants may re- quest more than they need, or because there are simply too many combinations of possible agreements to try out under time constraints. In these conditions, revealing the objectives of one or more of the participants may facilitate agreement, because the addi- Iyad Rahwan British Univ. in Dubai Univ. of Edinburgh Sherief Abdallah British Univ. in Dubai Univ. of Edinburgh tional information narrows the “search space” of possible of- fers, and may reveal new avenues of negotiation that were not known before. However, it is not obvious that the revelation of information by either party will necessarily improve the result of the negotiation. Goal revelation is potentially costly, because it exposes the revealing party’s position and negoti- ation strategies. For example, a participant that revealed its goals could have exposed itself to be very selfish in its past offers, and this may adversely affect the quality of the deals they are offered in the future. This paper proposes a novel interest-based negotiation pro- tocol in task settings, in which parties can prompt each other to reveal their goals at fixed points within the negotiation pro- cess. This protocol is inspired by recent negotiation proto- cols that allow participants to exchange information about be- liefs, goals or social aspects (Rahwan et al., 2003). We com- pare this interest-based protocol with an alternative position- based protocol where goal revelation is not allowed. We mea- sured people’s behavior under each of these protocols using a computer-mediated testbed comprising a conceptually simple game in which players negotiate and exchange resources to enable them to achieve their individual goals. This testbed has been used previously to analyze the decision-making strate- gies people deploy when interacting with computers, and the comparison of these strategies with those that people deploy when interacting with other people (Gal, Pfeffer, Marzo, & Grosz, 2004). The advantage of this testbed for studying interest-based negotiation is two-fold: First, it presents a real- istic analogue to the ways in which goals, tasks and resources interact in real-world settings, but it abstracts away the com- plexities of specific domains. Second, it supports transpar- ent, anonymous communication between subjects who are interacting together in laboratory conditions, avoiding exper- imenter effects and face-to-face communication. We conducted experiments in which different subjects in- teracted with each other using either interest- or position- based protocols on the same set of negotiation scenarios. These scenarios varied in the dependency relationships that hold between players (i.e., who needs whom), as well as the number of integrative (mutually beneficial) exchanges. Re- sults show that goal revelation using interest-based negoti- ation protocols leads to a higher likelihood of agreement, and a significant increase in benefit to the revealing player, as compared to the benefit obtained using the position-based protocol. In addition, using the interest-based protocol it- self has a positive effect on the social benefit to both parties which is significantly higher than the social benefit obtained using the position-based protocol. Further analysis revealed that interest-based negotiation is essentially a mechanism by
[1]
A. Rubinstein.
A BARGAINING MODEL WITH INCOMPLETE INFORMATION ABOUT TIME PREFERENCES
,
1985
.
[2]
Sarit Kraus,et al.
Reaching Agreements Through Argumentation: A Logical Model and Implementation
,
1998,
Artif. Intell..
[3]
Harri Ehtamo,et al.
Constraint proposal method for computing Pareto solutions in multi-party negotiations
,
2001,
Eur. J. Oper. Res..
[4]
L. Thompson,et al.
Social Utility and Decision Making in Interpersonal Contexts
,
1989
.
[5]
Antonis C. Kakas,et al.
Adaptive agent negotiation via argumentation
,
2006,
AAMAS '06.
[6]
S. Atran,et al.
Sacred Barriers to Conflict Resolution
,
2007,
Science.
[7]
Carl Karner,et al.
Perceived versus Actual Value of Color-Coding
,
1975
.
[8]
Ya'akov Gal,et al.
Learning Social Preferences in Games
,
2004,
AAAI.
[9]
Jeanne M. Brett,et al.
Goal Framing Predicts Strategy Revision: When and Why Negotiators Reach Integrative Agreements
,
2007
.
[10]
N. Iyadrahwa,et al.
Argumentation-based negotiation
,
2004
.
[11]
Jacquie D. Vorauer,et al.
Perceived Versus Actual Transparency of Goals in Negotiation
,
1998
.
[12]
Frank Dignum,et al.
On the Benefits of Exploiting Underlying Goals in Argument-based Negotiation
,
2007,
AAAI.