ASYMMETRIC INFORMATION AND THE ELECTORAL MOMENTUM OF PUBLIC-OPINION POLLS

This paper demonstrates that the existence of public opinion polls amplifies the effects of shifts in the distribution of the public's preferences over the issue space on the election's results. Voters evaluate candidates by their positions on the issue space and by a valence or general ability dimension. Some individual's (the informed) have more precise information about the relative abilities of candidates than others (the uninformed). Since public opinion polls reflect the information of the informed, high approval for a candidate at the polls signals to the uninformed that he is more likely to be abler. However, high approval may also reflect changes in the distribution of the public on the issue space. As a result the uninformed partly confuse the two effects and public opinion polls tend to reinforce the effects of shifts in the public's ideological preferences on election results. A shift to the right that shows up as more support for the right-wing candidate at the polls is partly interpreted as a higher efficiency of this candidate. As a result he wins with a higher margin than the margin he would have won with in the absence of polls or under perfect information. © 1991 Kluwer Academic Publishers.