1. Cristina Bicchieri University of Pennsylvania http://www.phil.upenn.edu/faculty/bicchieri (work done in collaboration with Azi Lev-On and Alex Chavez)

2. The ‘communication effect’: First found in Social dilemma experiments First found in Social dilemma experiments Face to face communication Face to face communication Communication increases cooperation 40% over base rate (Ledyard 1995, Sally 1995) Communication increases cooperation 40% over base rate (Ledyard 1995, Sally 1995) Effect still present in computer-mediated communication (Bicchieri and Lev-On 2007), but Effect still present in computer-mediated communication (Bicchieri and Lev-On 2007), but 1. Richness of medium matters (video, text) 2. More time than FtF to establish cooperation 3. Syncronous communication better

3. Why communication matters? Group identity (Dawes et al. 1977) Irrelevant communication may increase group identification, but cooperation stays low (17% in Bouas and Komorita, 1996) Distinguish relevant from irrelevant communication (Gachter and Fehr, 1999) Only discussion of game matters to cooperation Relevant communication always involves promising (Bicchieri, 2002)

4. Promising focuses subjects on social norms (promise keeping, reciprocity..) (Bicchieri, 2002, 2006), however: Background conditions of communication affect credibility of mutual promises Cues generated by FtF communication (visual, verbal, social) correlated with trustworthiness Enable formation of empirical and normative expectations of compliance Conditional preference to conform In social dilemma experiments with CMC, promises not perceived as credible  low cooperation (Brosig et al, 2003; Zheng et al., 2002). Group size fixed

5. Experiments: Trust games Relevant/Irrelevant communication Face to face/Computer-mediated Dyadic/Group communication

6. Experiment 1 (Bicchieri, Lev-On and Chavez, 2009) 64 participants Each plays 3 Trust games, randomly paired with different partners No feedback on amount returned Paid on two games, randomly chosen 5 experimental conditions: G1.1,2: control, no communication G2.1: Computer based text chat (5 min.), relevant G3.1: FtF communication (2 min.), relevant G2.2: Computer based text chat (5 min.), irrelevant G3.2: FtF communication (2 min.), irrelevant Experiment 1 (Bicchieri, Lev-On and Chavez, 2009) 64 participants Each plays 3 Trust games, randomly paired with different partners No feedback on amount returned Paid on two games, randomly chosen 5 experimental conditions: G1.1,2: control, no communication G2.1: Computer based text chat (5 min.), relevant G3.1: FtF communication (2 min.), relevant G2.2: Computer based text chat (5 min.), irrelevant G3.2: FtF communication (2 min.), irrelevant

7. after decision in each game, 1 st movers asked about expectation of 2 nd mover reciprocation analyze effects of communication relevance and medium on trust (how much is sent), reciprocity (amount returned relative to amount sent), and expected reciprocity (expected amount returned relative to amount sent) Relative to control, both relevance and medium had large, positive effect on all three dependent variables

8. Experiment1- Some Results Mean trust, reciprocity and expected reciprocity by communication relevance and medium ControlFtF relevant CMC relevant FtF irrelevant CMC irrelevant Trust2.635.575.144.173.28 Reciprocity1.927.575.143.331.94 Expected reciprocity 3.548.367.435.564.28

10. Trust:  Greater trust with relevant communication (majority sends $6)  No effect of communication medium on trust  Trust increases with expected reciprocity  Message relevance most conducive to create such expectations Reciprocity:  Bimodal pattern, either 0 or $9  Affected by medium and amount sent  Pattern depends on conditions: -- FtF relevant: almost all return $9 -- Control: almost all return zero -- When 1 st movers send less than $6, little is returned

13. When communication was restricted, there were no significant differences between the amounts sent following CMC and FtF communication, and the no-communication control

15. No Comm. FtF Dyadic CMC Dyadic FtF group CMC Group Trust3.035.575.144.123.94 Reciprocity1.837.575.143.622.12 Expected reciprocity 3.508.367.434.315.00 Mean trust, reciprocity and expected reciprocity by communication medium and group size

16. Some results

17. As a general rule, higher levels of trust, reciprocation, and expected reciprocity were recorded in the dyadic conditions, compared to the non-dyadic conditions The medium of communication did not significantly predict trust Trust level depends on group size and communication Reciprocity depends on trust, group size, medium -- probability returning each $ increases with amount sent, but increases more rapidly for dyadic conditions, and most rapidly for FtF dyadic

18. Bimodal Bimodal pattern of returns (zero or $9) -- pattern depends on communication condition, only partially on trust levels -- almost all 2 nd movers in dyadic FtF return $9 -- almost all 2 nd movers in control and CMC-group return zero Expected reciprocity is highest in dyadic communication  promises are more frequent  highest level of trust If group makes promises, trust/reciprocity more frequent than control

19. Implications for Cooperation in Computer- Mediated Environments Virtual work groups File sharing sites Web-supported collective action Interface Design Create opportunity for dyadic communication Video vs. audio conversation