Strategy-Proofness Made Simpler

There is evidence that many people do not report their types truthfully in strategy-proof mechanisms. One of the leading explanations is mechanism complexity. We propose a novel way of describing any strategy-proof mechanism with the aim to reduce the ensuing cognitive load on players and, hence, to increase truthful reporting. The description highlights that a player is guaranteed to obtain a most preferred feasible allocation based on her reported type and that feasibility depends only on the other players’ reports. Optimality of truthful reporting should therefore become more “apparent.” We experimentally test this prediction using the top trading cycles mechanism for matching applicants to positions. The proposed description increases truth-telling. This increase positively interacts with subject numeracy.