While electoral reforms clearly affect how seats are (re)distributed among parties immediately after their adoption, they do not significantly change the (re)distribution of votes among parties. As political knowledge is positively related to turnout, we argue that the effect of majoritarian electoral reforms on the number of parties is contingent upon the turnout in the last election prior to the reform. Specifically, the lower the turnout level in the previous election, the more effective the majoritarian reform will be. However, the psychological effect of proportional reforms relies on the interplay between elites and voters and is highly uncertain. The argument is tested using aggregated data from 43 major electoral reforms worldwide from 1945 to 2020 and individual data from the first election held in New Zealand after the 1993 electoral reform.