當民意的分佈是處於雙峰（bimodal）的狀態下，政黨則會去分別站在議題光譜的兩端，依賴各自選民的支持。而根據理性抉擇理論，選民事實上不一定充份的時間收集政治資訊，因此在投票前需要一個明確的線索來幫助他們做出投票決定。我們假設，當政黨長期以來對於某項議題具有明確的立場，議題的兩極化可能發生；當兩極化政治發生時，個人的議題立場會影響其投票決定。為了驗證這兩個論點，我們檢視在2004年總統大選中台灣國家認同以及統獨議題如何轉換為公投議題，並且形成兩極化政治。研究結果顯示出「領或不領公投票」的兩極化確實發生，進而影響選舉投票行為。

When opinions are polarized in a bimodal pattern, parties will occupy the two poles of the political issue, retaining the support of the extremists. According to rational choice theory, on the other hand, voters have inadequate time to collect political information, thus they need a clear shortcut to reach decisions. Our first proposition is that issue polarization will happen when political parties have long-term stances on certain issues. Our second proposition is that individual’s issue position will decide one’s voting behavior when polarization happens. To prove these two propositions, we examine how national identity and unification/independence issue transformed to the referendum issue in the 2004 presidential election. Our finding shows that whether or not picking up the referendum ballots indeed turned a polarized issue and it influenced voting behavior.