  The development and deployment of matching procedures that incentivize
truthful preference reporting is considered one of the major successes of
market design research. In this study, we test the degree to which these
procedures succeed in eliminating preference misrepresentation. We administered
an online experiment to 1,714 medical students immediately after their
participation in the medical residency match--a leading field application of
strategy-proof market design. When placed in an analogous, incentivized
matching task, we find that 23% of participants misrepresent their preferences.
We explore the factors that predict preference misrepresentation, including
cognitive ability, strategic positioning, overconfidence, expectations, advice,
and trust. We discuss the implications of this behavior for the design of
allocation mechanisms and the social welfare in markets that use them.
