ORCID

Abstract

Promises are crucial for human cooperation because they allow people to enter into voluntary commitments about future behavior. Here we present a novel, fully incentivized paradigm to measure voluntary and costly promise-keeping in the absence of external sanctions. We found across three studies (N = 4,453) that the majority of participants (61%–98%) kept their promises to pay back a specified amount of a monetary endowment, and most justified their decisions by referring to obligations and norms. Varying promise elicitation methods (Study 1a) and manipulating stake sizes (Study 2a) had negligible effects. Simultaneously, when others estimated promise-keeping rates (using two different estimation methods), they systematically underestimated promise-keeping by up to 40% (Studies 1b and 2b). Additional robustness checks to reduce potential reputational concerns and possible demand effects revealed that the majority of people still kept their word (Study 3). Promises have a strong normative power and binding effect on behavior. Nevertheless, people appear to pessimistically underestimate the power of others’ promises. This behavior–estimation gap may prevent efficient coordination and cooperation.

DOI

10.1162/opmi_a_00027

Publication Date

2019-07-30

Publication Title

Open Mind

Volume

3

First Page

68

Last Page

88

Embargo Period

2020-06-30

Organisational Unit

School of Psychology

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