Keeping One's Word: A Laboratory Study of Promises and Integrity1
Priyodorshi Banerjee2
Sujoy Chakravarty3
Sanmitra Ghosh4
21st November, 2012
Abstract
Promises are non-binding (and therefore costless) claims made by an agent to another in games
and decision theoretic situations, which have a potential effect on the payoffs of both parties.
Casual empiricism reveals that human beings do honour oaths and keep promises, sometimes at
high personal cost. We investigate numerical promise keeping in a dictator game and an
ultimatum game by adding a promise stage to both these games. In this stage, two competing
proposers promise to split their endowment in a certain way if selected by the recipient. This
promise is a non-binding claim which does not alter the equilibrium in either of these games. We
find that a significant number of subjects make offers close to what they promised, if they were
selected by the recipient. Furthermore we manipulate the nature of the salience of payments, by
conducting in addition to paid sessions, those where subjects with more points are rewarded with
higher scores in their course evaluation. For sessions involving either monetary rewards or classmarks, there is a stronger relationship between promise and offer for the ultimatum game vis-àvis the dictator game. Moreover for the dictator game, we define high integrity individuals as
those who have kept their promise at least once (where integrity = offer – promise) and have
never offered zero to the recipient. We find that offers made by these high integrity proposers are
significantly higher than those with lower levels of integrity.
1
This study has benefitted from the comments and suggestions received at the seminar series of the ERU at ISI
Kolkata. Anwesha Mukherjee, Srijita Das, Piyush Bhadani, Caroline E. Abraham and Sandip Datta provided
valuable research assistance. We retain the responsibility for all errors and omissions.
2
Economic Research Unit, Indian Statistical Institute (ISI), Kolkata
3
Centre for Economic Studies and Planning, Jawaharlal Nehru University (JNU), New Delhi and IMT Ghaziabad.
4
Department of Economics, Jadavpur University, Kolkata