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					   Where to look and why? :
 Utility and heuristics as explanations
 of cooperation in one-shot PD games


Shigehito Tanida & Toshio Yamagishi
           Hokkaido University
Overview
• Our Question:
  Why do people cooperate in one-shot
  PD games with an unrelated partner?

• We measured subject’s eye movements
  via an eye camera while Ss were looking at
  the matrix and making a decision in one-
  shot PD game.
• We examine the validity of explanation of cooperation in one-shot PD,
  analyzing relationship between the subject’s
  attention to the matrix and their decision.
    Two alternative explanations of
     cooperation in one-shot PD game
1. Utility transformation explanation
  – Social Value Orientation (SVO) (e.g., van Lange, 1999):
    Utility of an outcome in a social exchange
    (e.g., PD game) is a combination of
    1. Utility of own outcome 2. Utility of partner’s outcome
    3. Disutility of inequality of the two players’ outcomes

  Cooperators (Pro-Socials) are expected to pay
  more attention to the partner’s outcome than
  defectors.
  Defectors (Pro-Selfs) care only about their own
  outcome.
    Two alternative explanations of
     cooperation in one-shot PD game
2. Social Exchange Heuristic explanation
• Whether one cooperates or defects depends on
   how he/she define the game the two
  The relative plausibility of situation.
   In this approach, players’ decisions depend not for
• explanations will depend on how easy it is so
   much on the utilities of outcomes but rather as
  the player to intuitively grasp the game on an
   activation of a particular heuristic
 incidence of social exchange.
  SEH:A default decision rule in a social exchange
     that minimizes a condition that was
 We conducted two particular type of error
 When activated by cues of being in sense of
 manipulated the kind of intuitive a social
  exchange, it makes people seek mutual
 exchange. while avoiding being a sucker.
  cooperation
 Simple Matrix Condition
 • The gain of mutual cooperation is easy to understand

                                       Partner
                           Cooperate             Defect

                     Own    Partner       Own    Partner
    Cooperate
Subject
                1200 1200                0 1800
Defect   Own    Partner       Own      Partner
     1800        0          600 600
 Complex Matrix Condition
 • It is difficult to intuitively grasp that it represents a
   social exchange

  (simple payoff x .93) + 165           Partner
                            Cooperate              Defect

                     Own     Partner       Own     Partner
    Cooperate
Subject
                1281 1281               165 1839
Defect   Own      Partner      Own      Partner
     1839 165                723 723
Eye Movement Tracking
• We observed where in the PD matrix players
  looked at with an eye camera.

If the utility transformation explanation is valid,
  In both condition, Cooperators should look at
  their partner’s payoffs (compared to own
  payoffs) more than Defectors.

If the Heuristic explanation is valid,
  The cooperation rate and the proportion of
  fixation of mutual cooperation cell that Ss
  looked at in Simple Matrix condition should be
  higher than in the Complex Matrix Condition.
Result1: Cooperation rate & Proportion of the fixation
    • Cooperation rate

    Simple Matrix Condition: 44.8%
    Complex Matrix Condition: 36.7%            (χ2(1)=0.30, n.s.)


    • Proportion of the fixation

             Cooperators                   Defectors
               C       D                   C               D
      C    .38         .25         C     .23         .21
D
     .21         .16         D     .32     .25
 Which did Ss look at matrix? - Own or
 Partner's payoff?
              Complex Matrix Condition
     Result : Simple Matrix Condition
         1
         1                                      Own
               Own PayoffCooperate
                              p<.05   Partner
                                                Partner's
                                                   Defect
               Partner's Payoff
                     Own    Partner      Own      Partner
    Cooperate
                1200 1200               0 1800
Subject0.5
      0.5

Defect   Own     Partner      Own     Partner
     1800        0          600 600
         0
         0
               Cooperator
               Cooperator             Defector
                                      Defector
         • Proportion of fixation in Simple Matrix condition
                  C           D                       C         D
      C     .39             .27        C      .27           .22
D                                 D
     .21              .13             .28             .24
    Cooperators                           Defectors


         • Proportion of fixation in Complex Matrix condition
                  C          D                   C           D
     C    .38           .21           C     .17           .20
D
    .21           .21
                                  D   .37         .26
    Cooperators                           Defectors
Discussion
• The result of Defectors’ attention in
  Complex Matrix Condition indicated that
  players’ social motivation plays an important
  role in the situation that is lacking the kind of
  intuitive sense of exchange.

• Defectors in Simple Matrix Condition paid
  attention to the mutual cooperation cell,
  suggested that their decision is more likely
  to be driven by heuristics rather than
  transformed utilities.

				
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posted:12/19/2011
language:English
pages:12