Return Rates of “Lost” Letters as a Function of Whether the Letter is Stamped and Amount of Money Apparently in the Letter

Abstract

150 stamped and 150 unstamped letters with 3 different amounts of “play” money in them were “lost.” The return rate for stamped letters was significantly higher than the return rate for unstamped letters. Amount of “play” money in the letter did not have a significant effect upon return rate.