Announcement, observation, and honesty in the voluntary contributions game

International audienceIn this paper, we study the effect of pre-play announcements and ex-post observation of decisions on voluntary public good provision. We find that requiring announcements, in conjunction with making contribution decisions public, has a significantly positive effect on the average level of contributions. Those treatments, in which announcements are elicited, permit the truthfulness of subjects' announcements to be measured. We find that high contributors are more honest, the truthfulness of others is reciprocated with greater honesty and announcements are more honest when contribution decisions are observable