Promises as Commitments

30 Pages Posted: 1 Feb 2013 Last revised: 12 Jul 2016

Multiple version iconThere are 2 versions of this paper

Date Written: May 20, 2015


This Discussion paper has been substantially revised, and is now available under the title "Why do promises affect trustworthiness, or do they?" in Experimental Economics, June 2016, Volume 19, Issue 2, pp 382–393;

We set out to test whether the effect of promises on trustworthiness derives from the fact that they are made (internal consistency) or that they are received (social obligation). The results of an experimental trust game appeared at first to support the former mechanism. Even when trustee messages are not delivered to trustors, trustees who make a promise are more likely to act trustworthy than those who do not make a promise. However, we subsequently ran a control treatment with restricted (non-promise) communication to examine whether the correlation between promises and trustworthiness is causal. The results show that the absence of promises does not decrease average cooperation rates. This indicates that promises do not induce trustworthiness, they are just more likely to be sent by cooperators than by non-cooperators.

Keywords: promises, communication, commitment, endogeneity, experiment

Suggested Citation

Ismayilov, Huseyn and Potters, Johannes (Jan) J. M., Promises as Commitments (May 20, 2015). Netspar Discussion Paper No. 07/2012-057, Available at SSRN: or

Huseyn Ismayilov

Tilburg University ( email )

Tilburg, Noord-Brabant

Johannes (Jan) J. M. Potters (Contact Author)

Tilburg University - CentER ( email )

Department of Economics
P.O. Box 90153
5000 LE Tilburg
+31 13 466 8204 (Phone)
+31 13 466 3042 (Fax)

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