The Cognitive Number of Parties

• In Event: New Approaches in the Study of Citizen-Party Linkage

Abstract

The effective number of parties is the gold standard when political scientists count parties. Though its derivation lacks any theoretical foundation, it is widely used thanks to its intuitiveness to scholars. But do lay people really count parties in such a way? We define the cognitive number of parties (CNP) as how many parties an individual finds given vote shares among parties. We argue that everyone has his or her counting threshold in mind such that he or she counts parties with larger vote shares than the counting threshold. We suppose that the counting threshold varies across individuals, electoral systems, and which party obtains how much vote share. Accordingly, we expect that the CNP (1) is an integer, (2) increases in the magnitude of the district, (3) is larger under a single-member district than under a proportional representation district, and (4) is larger when the individual’s favorite party gets smaller vote share. We conducted our survey experiment to find that the first three of our four hypotheses are supported, but the last one is not.

Authors

• Kentaro Fukumoto, The University of Tokyo

• Hirofumi Miwa, Gakushuin University