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Smiling is a Costly Signal of Cooperation Opportunities: Experimental Evidence from a Trust Game

  • Centorrino, Samuele
  • Djemaï, Elodie
  • Hopfensitz, Astrid
  • Milinski, Manfred
  • Seabright, Paul

We test the hypothesis that "genuine" or "convincing" smiling is a costly signal that has evolved to induce cooperation in situations requiring mutual trust. Potential trustees in a trust game made video clips for viewing by potential trusters before the latter decided whether to send them money. Ratings of the genuineness of smiles vary across clips; it is difficult to make convincing smiles to order. We argue that smiling convincingly is costly, because smiles from trustees playing for higher stakes are rated as significantly more convincing, so that rewards appear to induce effort. We show that it induces cooperation: smiles rated as more convincing strongly predict judgments about the trustworthiness of trustees, and willingness to send them money. Finally, we show that it is a honest signal: those smiling convincingly return more money on average to senders. Convincing smiles are to some extent a signal of the intrinsic character of trustees: less honest individuals find smiling convincingly more difficult. They are also informative about the greater amounts that trustees playing for higher stakes have available to share: it is harder to smile convincingly if you have less to offer.

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Paper provided by Institut d'Économie Industrielle (IDEI), Toulouse in its series IDEI Working Papers with number 669.

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Date of creation: Apr 2011
Date of revision:
Handle: RePEc:ide:wpaper:24350
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  1. Scharlemann, Jorn P. W. & Eckel, Catherine C. & Kacelnik, Alex & Wilson, Rick K., 2001. "The value of a smile: Game theory with a human face," Journal of Economic Psychology, Elsevier, vol. 22(5), pages 617-640, October.
  2. Ronald Bosman & Frans van Winden, 2002. "Emotional Hazard in a Power-to-take Experiment," Economic Journal, Royal Economic Society, vol. 112(476), pages 147-169, January.
  3. Astrid Hopfensitz & Ernesto Reuben, 2009. "The Importance of Emotions for the Effectiveness of Social Punishment," Economic Journal, Royal Economic Society, vol. 119(540), pages 1534-1559, October.
  4. Hwang, Sung-Ha & Bowles, Samuel, 2012. "Is altruism bad for cooperation?," Journal of Economic Behavior & Organization, Elsevier, vol. 83(3), pages 330-341.
  5. Daniel Kahneman, 2003. "A Psychological Perspective on Economics," American Economic Review, American Economic Association, vol. 93(2), pages 162-168, May.
  6. George Loewenstein, 2000. "Emotions in Economic Theory and Economic Behavior," American Economic Review, American Economic Association, vol. 90(2), pages 426-432, May.
  7. Jon Elster, 1998. "Emotions and Economic Theory," Journal of Economic Literature, American Economic Association, vol. 36(1), pages 47-74, March.
  8. Bruno S. Frey, 2008. "Happiness: A Revolution in Economics," MIT Press Books, The MIT Press, edition 1, volume 1, number 0262062771, June.
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